1. Nutrition 26 (2010) 312–320
www.nutritionjrnl.com
Basic nutritional investigation
Effects of cafeteria diet on the jejunum in sedentary
and physically trained rats
Celia Regina Scoaris, M.D.a,*, Gabriela Vasconcelos Rizo, M.D.a, Luciana Patrıcia Roldi, M.D.a,
´ ´
Solange Marta Franzoi de Moraes, Ph.D.a, Andre Ricardo Gomes de Proenca, M.Sc.a,
´ ´ ¸
Rosane Marina Peralta, Ph.D. , and Maria Raquel Marcal Natali, Ph.D.a
b
¸
a
Department of Morphophysiological Sciences, State University of Maringa, Maringa, Parana, Brazil
´ ´ ´
b
Department of Biochemistry, State University of Maringa, Maringa, Parana, Brazil
´ ´ ´
Manuscript received December 4, 2008; accepted April 15, 2009.
Abstract Objective: The effects of a cafeteria diet on the small intestine were investigated in adult Wistar rats
under sedentary conditions and after physical training.
Methods: Parameters including morphometry, enzyme activities, and total myenteric populations in
the jejunum were evaluated.
Results: The cafeteria diet, characterized as hyperlipidic, produced obese rats, corroborated by in-
creases in the Lee index and the weights of the periepididymal and retroperitoneal adipose tissues
(P < 0.01). Obesity caused increases in the length of the small intestine, villi height, crypt depth,
whole-wall thickness (P < 0.05), and the enzymatic activities of alkaline phosphatase, lipase, and su-
crase (P < 0.01), in addition to a reduction in the number of goblet cells (P < 0.05). With reference to
the jejunal intrinsic innervations, the total number and area of myenteric neurons was unchanged re-
gardless of the group. Physical training promoted 1) a reduction of the weight in the retroperitoneal and
periepididymal adipose tissues (P < 0.05) and 2) an increase in the thickness of the muscular layer
(P < 0.05).
Conclusion: The cafeteria diet promoted obesity in rodents, leading to alterations in morphometry
and enzymatic intestinal parameters, which were partily attenuated by physical training. Ó 2010
Elsevier Inc. All rights reserved.
Keywords: Cafeteria diet; Intestinal morphometry; Jejunum; Myenteric neurons; Obesity; Physical training
Introduction hypertrophic and hyperplastic alterations in adipocytes, lead-
ing to weight gain from an energy imbalance [2].
The increasing incidence of obesity is a serious public Health complications attributable to obesity frequently de-
health issue worldwide. According to the World Health scribed in the literature include diabetes, cardiovascular
Organization, there are more than 1 billion overweight adults disease, orthopedic and postural alterations, breathing and
with a body mass index (BMI) !25 kg/m2 and around 300 emotional disorders, hepatic steatosis, and gastrointestinal al-
million people with a BMI !30 kg/m2 [1]. The etiology of terations, which affect the quality of life and increase the risk
obesity is extremely complex because of the involvement of death.
of neurologic, endocrine, genetic, and behavioral factors. The current obesity epidemic requires a change in life
Obesity is characterized by increased energy storage and habits, considered from an evolutionary point of view. Previ-
ously, men were adapted to periods of physical effort for sur-
vival because of a lack of food and the need to obtain fresh
This work was financed by the Conselho Nacional de Desenvolvimento food and fiber. At present, humanity leads a more sedentary
Cientıfico e Tecnologico and Fundacao Araucaria.
´ ´ ¸˜ ´
*Corresponding author. Tel.: þ55-44-3261-4704; fax: þ55-44-3222-
life, associated with industrialized, refined aliments, satu-
8866. rated fat, and low fiber. The impact of obesity can be
E-mail address: celiareginabio@hotmail.com (C. R. Scoaris). decreased through regular physical activity, restoration of
0899-9007/10/$ – see front matter Ó 2010 Elsevier Inc. All rights reserved.
doi:10.1016/j.nut.2009.04.012

2. C. R. Scoaris et al. / Nutrition 26 (2010) 312–320 313
a positive energy balance, promotion of antioxidant defense procedures of the study were approved by the committee of
mechanisms, and by decreasing the occurrence of diseases ethics on animal experimentation of the State University of
associated with oxidative stress [3]. Maringa.´
Experimental animal models resembling human obesity According to the diet type and physical activity, 28 ani-
include those in which a hyperlipidic diet (also referred to mals were allocated to four groups: sedentary normally fed
as a cafeteria diet), Western diet, or fast-food diet is used rats (SN), sedentary rats fed a cafeteria diet (SCa), trained
[4–8]. This diet, although with increased energy value, has normally fed rats (TN), and trained rats fed a cafeteria diet
low nutritive value, because it is overloaded with carbohy- (TCa). During the experimental period of 120 d, animals
drates, fat, or both [4]. This type of diet is characterized by were housed in polypropylene boxes at room temperature
its capacity to induce not only increased lipid storage in the (24 6 2 C) under a 12-h light/12-h dark cycle.
adipose tissue but also increased oxidative stress throughout
the system [5]. Diet
The small intestine is responsible for digesting and ab-
sorbing nutrients and is structurally adapted to carry out these Animals from the SN and TN groups received standard ro-
functions. It has a large surface area and functions in trigger- dent chow (Nuvilab-Nuvital (Curitiba, PR, Brazil), recom-
ing signals to the central nervous system and ensuring energy mended by the National Research Council and National
homeostasis [9]. The intestinal mucosa is sensitive to alter- Institutes of Health, Bethesda, MD, USA) and water ad libi-
ations in this environment, with hypertrophy when there is tum. Animals from the cafeteria groups (SCa and TCa) re-
food overload and atrophy when there is a lack of food [10]. ceived a cafeteria diet [4–8] consisting of the usual pellets
In obesity conditions induced by the administration of of standard diet, cheese or bacon-flavored chips, bread, choc-
monosodium glutamate (MSG), intestinal morphometric pa- olate, marshmallows, peanut candy, filled cookies, wafer
rameters, such as the villi, crypts, and muscular-coat thick- cookies, sausage, and mortadella, in addition to ad libitum
ness, were maintained in the jejunum of mice [11] and soda and water. The standard rodent diet and cafeteria diet
ileum of rats [12]. Enzymatic activity can be altered accord- were analyzed in terms of the percentage of macronutrients
ing to the alimentary substrate. Increased activity of alkaline and fiber content by the Laboratory of Animal Nutrition,
phosphatase was found in the jejunum of obese rats due to the Zootechny Department, Maringa State University.
´
intake of a hyperlipidic diet [13]. Diet consumption, in grams and calories, was measured
The small intestine is extrinsically innervated by the auto- daily, and liquid consumption and body weight were mea-
nomic nervous system, and its activity is modulated intrinsi- sured three and two times per week, respectively.
cally by the enteric nervous system. This system is organized
into a complex network of nerve fibers and neuronal cell Physical training
bodies (e.g., interneurons, motor and sensory neurons). The
myenteric plexus is one of the main ganglionated plexuses After 30 d of feeding on a cafeteria diet, animals were sub-
comprising the enteric nervous system, which is located be- jected to physical training for a period of 12 wk, consisting of
tween the inner circular muscular coat and the outer longitu- treadmill running (Inbrasport, Porto Alegre, Brazil) from
dinal muscular coat of the digestive tract and responds to 16:30 to 18:30 h, with a previous training adaptation period
intestinal motility, among other functions [9,12,14–19]. of 10 min, at speeds ranging from 0.3 to 0.6 km/h. The train-
Morphologic and quantitative variations in the enteric ing protocol [20] consisted of running five times per week,
neurons occur according to age [14,15], denervation model ranging from 15 to 60 min of training per session, with a vari-
[16], diabetes [17], diet restriction [18], obesity induced by able speed from 0.3 to 1.4 km/h and no change of treadmill
neonatal administration of MSG [12], and physical training tilt.
[19].
Because myenteric neurons are sensitive to alterations in Tissue collection
the tension of the intestinal wall and the chemical environ-
ment of the intestine, the present study aimed to evaluate When animals were 190 d old, they were weighed, anes-
morphometric and enzymatic parameters, in addition to the thetized with sodium thiopental (Thionembutal (Sao Paulo,
˜
population of myenteric neurons, in the jejunum of obese Brazil), 40 mg/kg, intraperitoneally), and their nasal–anal
rats, which were sedentary or subjected to physical training. length was measured to obtain the Lee index (body
weight1/3 [g]/nasal–anal length [cm] 3 1000) [21]. Subse-
Materials and methods quently, laparotomy was carried out and the periepididymal
and retroperitoneal adipose tissues were dissected out from
Animals the small intestine; the weights and lengths (from the pylori
to the ileocecal junction) of these dissected samples were
The present study used male 70-d-old Wistar rats (Rattus measured. The jejunum was isolated, its width was measured,
norvegicus) with an initial average weight of 270 g from the and it was divided into samples, which were further subjected
Animal House of the State University of Maringa. All animal
´ to the following protocols: histologic processing and

3. 314 C. R. Scoaris et al. / Nutrition 26 (2010) 312–320
embedding in paraffin for the morphometric study of the (50 mM, pH 6.5), and centrifuged for 15 min at 4 C at
muscular coat and total wall; inclusion in historesin for the 4000 rpm. The supernatant was further used to determine
morphometric evaluation of intestinal crypts and villi; the levels of alkaline phosphatase [22], lipase [23], sucrase
histochemistry to evaluate goblet cell population; analysis [24], b-galactosidase [22], and maltase [25].
of intestinal enzymes (alkaline phosphatase, lipase, b-galac- For all enzymes, a unit of enzymatic activity was defined
tosidase, maltase, and sucrase); and whole-mount prepara- as the enzyme quantity that produced 1.0 mmol of product per
tions to evaluate the total myenteric population. milliliter within 1 h under experimental conditions. The spe-
cific activity was expressed as units per gram of jejunum (wet
Morphometric analysis of the jejunal wall weight).
Jejunal samples of five animals from each group were col- Whole-mount preparations
lected, opened along the mesenteric insertion, washed with
saline solution, and adhered in polystyrene. Samples were Jejunal samples of seven rats from each experimental
fixed in Bouin’s solution for 6 h, dehydrated using graded- group subjected to whole-mount preparations were used for
concentration solutions of ethanol (70%, 80%, 90%, and this study. The samples were stained by the Giemsa method
100%), diaphanized in xylol, and embedded in histologic [26] that allows estimations of the total myenteric population.
paraffin. Transverse semi-serial sections of 5-mm thickness Samples were excised, and the lumen, after washing with sa-
were obtained using a Leica RM 2145 microtome (Leica Mi- line solution, was filled with Giemsa fixer using a syringe.
crosystems, Wetzlar, Germany) with a steel knife. The histo- The edges were tied to form a ‘‘balloon’’ and immersed in
logic sections were stained with hematoxylin and eosin to the same solution for a period of 24 h.
evaluate the muscular coat and intestinal wall (from the top Subsequently, the samples were opened along their mes-
of the villi to the serosa coat). Subsequently, 50 points each enteric border and microdissected under a transillumination
(micrometers) were measured at random in the muscular stereomicroscope, removing the mucosa and submucosa
coat and intestinal wall per animal. coats, while simultaneously preserving the muscular and se-
rosa coats, to obtain the whole-mount preparations. These
Morphometric analysis of intestinal villi, samples were stained with Giemsa stain, consisting mainly
crypts, and goblet cell populations of methylene blue in 0.1 N Sorensen buffer (pH 6.9), under
agitation for 24 h. The samples were then dehydrated in alco-
To evaluate villi height, crypt depth, and total population hol, diaphanized in xylol, assembled over slides, and cover-
of goblet cells, the jejunum samples of five animals per group slipped with Permount synthetic resin.
were collected and opened along the mesenteric insertion and
fixed in Bouin’s solution. After fixation, they were dehy- Quantitative analysis and neuronal morphometry
drated and embedded in 2-hydroxy-methacrylate resin (Leica
Microsystems). Transverse semi-serial sections of 2-mm The myenteric neurons present in 80 microscopic fields
thickness were obtained using a Leica RM 2145 microtome; were randomly quantified using an optical microscope
the sections were stained with hematoxylin and eosin to mea- (Olympus) with a 403 objective for the whole-mount prepa-
sure the height of 90 villi and the depth of 90 crypts per rations in the intermediate (60–120 and 240–300 degrees)
animal. and antimesenteric (120–240 degrees) regions, with refer-
Semi-serial sections were also subjected to the histochem- ence to the mesenteric insertion of the intestinal circumfer-
ical periodic acid–Schiff staining technique to quantify the ence [27]. Each field corresponded to 0.224 mm2, totaling
goblet cell population in 50 microscopic fields (0.352 mm2) 17.92 mm2/animal. The measurements (square micrometers)
per animal from 10 histologic sections. Morphometric analy- of the cell bodies of 100 neurons/animal, for a total of 700
sis was carried out using the images obtained from a high- neurons per studied group, were obtained using computer-
resolution camera (Q Color 3 Olympus American, Burnaby, ized image analysis (Image Pro Plus 4.5, Media Cybernetics).
BC, Canada) coupled to an Olympus BX 41 microscope The mean value 6 standard deviation for each group was ob-
(Olympus, Tokyo, Japan); subsequently, these images were tained, and the neurons were distributed in class intervals of
transmitted to a computer using Q Capture Pro 5.1 and Im- 100 mm2 according to neuronal area.
age-Pro Plus 4.5 (Media Cybernetics, Silver Springs, MD,
USA). Statistical analysis
Intestinal enzyme levels Statistical analysis was carried out using GraphPad Prism
3.0 (GraphPad Software, San Diego, CA, USA). Two-way
Jejunal samples of five animals from each group were col- analysis of variance was followed by Bonferroni’s post hoc
lected, frozen in liquid nitrogen, and stored in a freezer at test to compare the mean values. Levels of p 0.05 were
À80 C. Samples were weighed, cut out, macerated with considered statistically significant. Results are presented as
treated sand, suspended in 4 mL of sodium phosphate buffer mean 6 standard deviation.

4. C. R. Scoaris et al. / Nutrition 26 (2010) 312–320 315
Table 1
Alimentary consumption, caloric consumption, percentages of protein, lipid, and fiber; and consumption of daily water, soda, and total liquid in SN, SCa, TN, and
TCa rats*
SN SCa TN TCa
Consumption (g) 25.92 6 2.52 25.32 6 4.41 24.41 6 1.79 26.65 6 5.02
Consumption (kcal) 101.10 6 8.83 89.63 6 14.63 95.24 6 7.01 95.48 6 15.88
Protein (%)y 22.23 9.98 22.23 9.98
Lipids (%)y 4.00 16.22 4.00 16.22
Fiber (%)y 5.73 1.46 5.73 1.46
Water (mL) 40.19 6 10.55 14.98 6 7.09 39.90 6 9.87 13.72 6 6.57
Soda (mL) — 24.62 6 13.40 — 27.22 6 13.11
Total liquid (mL) 40.19 6 10.55 39.60 6 16.69 39.9 6 9.87 40.94 6 14.65
SCa, sedentary rats fed a cafeteria diet; SN, sedentary normally fed rats; TCa, trained rats fed a cafeteria diet; TN, trained normally fed rats
* Values are expressed as mean 6 SD (n ¼ 7 per group).
y
Laboratory of Animal Nutrition, Zootechny Department, Maringa State University.
´
Results and thereby produced obese rats. Physical training did not at-
tenuate this condition. The highest weight in the adipose tis-
Alimentary consumption and macronutrient percentage sues (periepididymal and retroperitoneal), in addition to their
sum, was found in the SCa and TCa groups compared with
The results refer to alimentary, caloric, and liquid con- the other groups. Obesity was confirmed in these rodents.
sumption, in addition to percentages of the macronutrients The weights of the periepididymal and retroperitoneal adi-
and fiber content of the diets (Table 1). The cafeteria diet is pose tissues, and their sum, were reduced in trained animals
characterized as hyperlipidic, hypoproteic, and isocaloric, as- regardless of their nutritional condition.
sociated with reduced fiber content. The lack of significant
differences in the alimentary intake in all groups indicates Intestinal morphometry
that diet and physical training did not alter the alimentary in-
take of these animals and that they were, hence, normopha- The values obtained for intestinal length in the SN, SCa,
gic. Total liquid consumption was similar among all the TN, and TCa groups, respectively, were 118.86 6 6.04,
groups studied; however, consumption of soda by the SCa 124.43 6 5.26, 121.57 6 3.46, and 124.43 6 3.26 cm. The
and TCa groups was higher compared with that of water. values obtained for intestinal width were 1.01 6 0.38,
0.87 6 0.4, 0.80 6 0.18, and 0.86 6 0.15 cm, respectively.
Validation of the obesity model The lengths of the small intestine were significantly different
in the groups that received the cafeteria diet.
Results validating the induction of the obesity condition The morphometric results regarding villi height, crypt
subsequent to consumption of a cafeteria diet are presented depth, intestinal total wall, and muscular-coat thickness and
in Table 2. Animals that consumed this diet for 120 d gained the quantification of total goblet cell population are presented
more weight compared with normally fed animals. Physical in Table 3. The cafeteria diet increased the villi height, crypt
training was not effective in reducing or controlling weight depth, and total wall thickness. Physical training did not in-
gain. Trained TN and TCa groups were not different in terms fluence these parameters.
of weight from the SN and SCa groups. Physical training promoted a significant increase in the
The Lee index, a parameter considered analogous to the muscular coat in animals of the physical training groups com-
BMI, was high in animals that received the cafeteria diet pared with the control group.
Table 2
FW, Lee index, PER and RET weights, and S in SN, SCa, TN, and TCa rats*
SN SCa TN TCa
z
FW (g) 422.30 6 39.50 523.20 6 52.00 393.90 6 37.70 522.80 6 47.50z
Lee indexy 304.60 6 7.40 322.20 6 11.30z 303.90 6 5.40 320.10 6 7.00z
PER (g/100 g body weight) 1.29 6 0.40 2.30 6 0.52z 0.89 6 0.13x 2.01 6 0.35zx
RET (g/100 g body weight) 1.48 6 0.34 3.54 6 0.64z 1.09 6 0.24x 3.23 6 0.41zx
S (g) 2.77 6 0.70 5.84 6 0.82z 1.98 6 0.34x 5.24 6 0.70zx
FW, final body weight; PER, weight of periepididymal adipose tissue; RET, weight of retroperitoneal adipose tissue; SCa, sedentary rats fed a cafeteria diet;
SN, sedentary normally fed rats; TCa, trained rats fed a cafeteria diet; TN, trained normally fed rats; S, fat sum
* Values are expressed as mean 6 SD (n ¼ 7 per group).
y
Lee index ¼ body weight1/3(g)/nasal–anal length (cm) 3 1000.
z
P 0.01 compared with SN and TN groups.
x
P 0.05 compared with SN and SCa groups.

5. 316 C. R. Scoaris et al. / Nutrition 26 (2010) 312–320
Table 3
Intestinal morphometry: villi height, crypt depth, muscular coat thickness, total wall, and number of goblet cells in SN, SCa, TN, and TCa rats*
SN SCa TN TCa
y
Villi height (mm) 379.53 6 45.90 530.80 6 50.70 407.91 6 68.35 540.45 6 63.99y
Crypt depth (mm) 164.83 6 21.67 205.02 6 20.65y 195.10 6 19.24 204.60 6 26.05y
Muscular-coat thickness (mm) 76.67 6 19.87 87.70 6 16.18 104.07 6 16.85z 102.66 6 15.29z
Total wall (mm) 616.70 6 55.77 726.02 6 53.20y 616.74 6 83.80 721.18 6 72.38y
Goblet cells (50 images/animal) 233.80 6 40.41 194.50 6 36.30y 216.00 6 35.83 165.24 6 26.67y
SCa, sedentary rats fed a cafeteria diet; SN, sedentary normally fed rats; TCa, trained rats fed a cafeteria diet; TN, trained normally fed rats
* Values are expressed as mean 6 SD (n ¼ 5 per group).
y
P 0.05 compared with SN and TN groups.
z
P 0.05 compared with SN and SCa groups.
The histochemical periodic acid–Schiff reaction showed terized as hyperlipidic [4–8], hypoproteic, and isocaloric.
a significantly lower goblet cell population in the cafeteria Reports describing high-lipid diets offered to rodents are
groups (SCa and TCa) compared with the controls (SN and found in the literature [4–7,13,28,29], including those inves-
TN). tigating the maintenance of caloric consumption [7,28]. This
model resembles human obesity, where diets with a high lipid
Enzymatic analysis value and an overload of carbohydrates and/or fat are the
causative factors [4–8].
The activities of the enzymes alkaline phosphatase, lipase, No differences were observed with reference to diet con-
b-galactosidase, maltase, and sucrase are presented in Table 4. sumption and/or training, thus maintaining the normophagic
A significant increase was observed in the enzymatic activi- behavior in all groups. The cafeteria diet in the present study
ties of alkaline phosphatase, lipase, and sucrase in animals did not stimulate higher food intake despite being described
that received the cafeteria diet. b-Galactosidase and maltase as highly palatable, thereby leading to hyperphagia [30] or
did not significantly differ among the groups. hypophagia [8] based on caloric surplus.
Physical training was not effective in changing the behav-
Quantitative analysis and morphometry of myenteric ior of the animals, similar to the results obtained in mice
neurons trained on treadmills [31]; however, this result is in contrast
to other studies in which rats ran on wheels [32] or swam de-
The total myenteric population, quantified by the Giemsa spite consuming a hyperlipidic diet [8]. Thus, an anorexi-
method, did not vary between the groups, in contrast to the genic effect attributed to physical activity [33] was not
average number of myenteric neurons and mean neuronal verified in the conditions under which the animals of this
area (square micrometers) of cell bodies (Table 5), indicating study were trained. The lack of intake reduction in terms of
the lack of any effect due to obesity or physical training. Fig- grams of the trained animals may be attributable to the long
ure 1 shows the neuronal distribution according to size in the training period or intensity [33] to which they were subjected
class intervals of 100 mm2 and indicates that the class interval (90 d with moderate intensity), thereby facilitating adaptation
between 101 and 200 mm2 was prevalent in the normally fed and maintenance of a balanced consumption. In experiments
groups and that between 201 and 300 mm2 was for the cafe- in which physical training led to lower chow consumption,
teria diet–fed groups. the training duration was short [32] or moderate [8].
The maintenance of rats on the cafeteria diet in the present
Discussion study for a period of 120 d provided excess lipid [4] and re-
duced fiber [6], thus promoting an increase in body weight
The cafeteria diet [4–8] administered to rats in the present [4–7,28]. The normally fed animals had a lower percentage
study promoted the development of obesity and was charac- of lipid intake and higher percentage of fiber intake compared
Table 4
Enzymatic activity in SN, SCa, TN, and TCa rats*
SN SCa TN TCa
y
Alkaline phosphatase (U/g jejunum) 5.34 6 0.68 10.30 6 2.06 5.22 6 1.08 9.62 6 2.72y
Lipase (U/g jejunum) 6.79 6 1.37 7.94 6 0.97y 5.16 6 0.42 8.55 6 2.13y
Sucrase (U/g jejunum) 51.94 6 5.24 69.48 6 6.18y 49.50 6 5.03 69.65 6 7.17y
b-galactosidase (U/g jejunum) 16.71 6 4.84 12.35 6 1.96 14.17 6 2.51 16.27 6 4.00
Maltase (U/g jejunum) 308.10 6 59.52 344.60 6 52.82 291.20 6 78.36 299.60 6 74.44
SCa, sedentary rats fed a cafeteria diet; SN, sedentary normally fed rats; TCa, trained rats fed a cafeteria diet; TN, trained normally fed rats
* Values are expressed as mean 6 SD (n ¼ 5 per group).
y
P 0.01 compared with SN and TN groups.

6. C. R. Scoaris et al. / Nutrition 26 (2010) 312–320 317
Table 5
Myenteric neurons in an area of 17.92 mm2 and neuronal cell body area in SN, SCa, TN, and TCa rats*
SN SCa TN TCa
2
Myenteric neurons in 17.92-mm area 7276.2 6 1338.4 6938.1 6 917.2 6709.5 6 1422.5 6829.1 6 1053.1
Neuronal cell body area (mm2) 199.9 6 63.6 240.1 6 68.0 204.5 6 63.1 217.3 6 60.4
SCa, sedentary rats fed a cafeteria diet; SN, sedentary normally fed rats; TCa, trained rats fed a cafeteria diet; TN, trained normally fed rats
* Values are expressed as mean 6 SD (n ¼ 7 per group).
with those on the cafeteria diet. Fiber leads to satiety because consequent importance of physical exercise in the control
of the distention mechanism of the stomach, thus increasing of adipose tissue mass.
intestinal motility and elimination of nutrients, in addition to
contributing to decreased body weight. Intestinal morphometric parameters
The final body weights corresponded with measurements
of the nasal–anal lengths, which were used to calculate the The cafeteria diet promoted an increase in the length of the
Lee indexes [21] (analogous to BMI). The Lee index was sig- small intestine. The values obtained in this experiment are
nificantly high, proving the obesity of the investigated ani- similar to those described in the literature for rats that became
mals. Similar results have been found previously in obese obese after intake of the cafeteria diet introduced after the
rodents [12,13]. No influence of physical training was found postweaning period until 90 d of age; those rats showed a sig-
with reference to body weight in the normally fed groups [34] nificant increase in small intestine length, which is justified
or in those that received a hyperlipidic diet combined with because of the typical reduction in the fiber content, increase
physical training [29]. in storage capacity, and caloric intake [6]. A lack of effect of
Weight of the adipose tissue is also an indicator of obesity. physical training on the intestinal length was also observed,
The cafeteria diet leads to an increase in periepididymal and consistent with results obtained for rats trained in treadmill
retroperitoneal adipose tissue weights and in the sum of these running for 180 d [35], suggesting that the same rats would
tissue weights, consistent with previous reports [4–7]. This not show any alteration after a prolonged training period.
increase is directly related to the tissue cellularity. A diet When the complete jejunal wall was evaluated, a signifi-
rich in carbohydrates and/or lipids promotes increases in cant increase was found in its thickness in the cafeteria group,
cell size and the number of adipocytes [2]. With reference without any apparent influence of the physical training. This
to training of the TN or TCa groups, the deposits of adipose difference may be a consequence of the tissue response of the
tissue were reduced before the end of the experiment. The mucosa or muscular coat, which are very sensitive to envi-
data related to the TCa group showed an interaction between ronmental influences in the intestinal lumen, mainly the intes-
physical training and diet. This interaction was significantly tinal mucosa [10,36]. When nutrients are provided, the
different for the adipose tissue mass, where the physical ex- intestinal mucosa is maintained; the mucosa tends to atrophy
ercise was able to attenuate the deleterious effect of the when nutrients are absent, with kinetic reductions in the intes-
diet. A statistically significant reduction was also found tinal crypts [10] and reductions in villi height and crypt depth
with a simultaneous combination of the hyperlipidic diet in rats fed a hypoproteic diet [36].
and treadmill running [29] or swimming [7] in rats, thus The response involving villi height and crypt depth signif-
indicating a positive effect of physical training and the icantly increased in animals that received the cafeteria diet
450
400
Frequencies of the cellular
350
300
body areas
250
200
150
100
50
0
0-100 101-200 201-300 301-400 401-500 501-600
Cellular body areas (µm2)
Fig. 1. Frequency distribution of cellular body areas of myenteric neurons (700 neurons/group), classified in intervals of 100 mm2, in the following groups of rats:
sedentary normally fed rats (white bars), sedentary rats fed a cafeteria diet (black bars), trained normally fed rats (speckled bars), and trained animals fed a cafeteria
diet (striped bars).

7. 318 C. R. Scoaris et al. / Nutrition 26 (2010) 312–320
compared with the control animals. These results suggest that Enzymatic intestinal parameters
the type of aliment, and not the consumed amount, was re-
sponsible for the hypertrophic effect observed in the villi The measurement of intestinal enzyme activity is an im-
and crypts in the jejunum of obese animals. This hypothesis portant tool for understanding the physiology of the intestine
has been corroborated by other studies [37] that verified the under normal and pathologic conditions [46]. Enzymatic ac-
increase in villi height in the jejunum and mucosal protein tivity can vary according to the level of substrates in the diet
content in response to a high-lipid (70%) diet that led to in- [13] and nutrient conditions, such as starvation or availability
creases in digestion and surface of absorption. Notably, com- of food [47].
pared with the control, the cafeteria diet in this study showed The activities of alkaline phosphatase and lipase are mod-
a difference of 75.34% in the lipid percentage. Lipid concen- ulated by the presence of dietary lipids [13]. Increased alka-
trations stimulated increases in villi height and crypt depth in line phosphatase activity was observed in obese rats after
SCa and TCa animals. The reduced protein concentration consumption of a hyperlipidic diet [13] and after MSG ad-
could lead to a decrease in the height and surface area of je- ministration [47]. This increase is justified because alkaline
junum villi in rats [38]. Although the protein content in the phosphatase is involved in the modulation of fat tissue in
diet used for this study was low, the influence from the lipid a few types of obesity, in which fat and body weight cannot
surplus may be a determinant for the response observed. be explained simply by hyperphagia [13,47]. Notably, in the
The increase in the intestinal surface area of cafeteria an- present experiments, cafeteria diet–fed rats (hyperlipidic)
imals (SCa and TCa) caused by the presence of increased villi showed normophagic behavior.
and crypts suggests that the capacity of absorption was max- No influence of diet or training was found on the lactase
imized, justifying the weight gain of these animals and the and maltase activities. High-carbohydrate diets, independent
fact that physical training in this study did not reverse this of whether the administration regimen was short (7 d in rats)
condition. [48] or prolonged (385 d in mice) [49], increased the activity
The increase in muscular-coat thickness in the jejunum in of sucrase, corroborating the results of this study.
response to physical training was observed independently of The difference in the response of intestinal sucrase, with
the nutritional condition, with a possible influence on intesti- reference to the other two enzymes, maltase and lactase,
nal motility [39]. The production of free radicals, under con- could be attributed to the higher amount of the respective
ditions of short [40] and long [41] training with different substrate in the diet. This evaluation was, however, not car-
intensities, in the smooth musculature of the organs are dis- ried out in the present study, although considering the aliment
cussed in depth in the literature and are suggested to be re- type provided, sucrose was the most predominant substrate,
sponsible for these alterations. followed by maltose—which are present in high, but insignif-
Smaller numbers of goblet cell populations were esti- icant, levels in the cafeteria diet.
mated in the jejunum of animals from the cafeteria groups
(SCa and TCa). Goblet cells are involved in the production Intestinal intrinsic innervation
of mucous that protects and lubricates the intestinal epithe-
lium surface, histochemically proved by periodic acid–Schiff The intrinsic innervation of the jejunum was evaluated
staining. Although villi height and crypt depth were in- through quantification and morphometry of the total myen-
creased in obese animals, this condition was not reflected teric population using whole-mount preparations stained
in the overall goblet cell population, indicating the involve- with the Giemsa method [12,14,26,27] based on the affinity
ment of other factors with the kinetics of this cell type. One of methylene blue for the acidic compounds that are found
of these factors may be the consistency of food in the cafete- in the neuronal cytoplasm (rough endoplasmic reticulum
ria diet, characterized as being smooth, with a higher fat con- and free ribosome). Although quantification in the jejunum
tent and lower fiber content, compared with the pellets had been carried out in the intermediate and antimesenteric
offered to the normally fed control groups. Different textures region to guarantee homogeneity of the results [27], there
and higher fiber content would demand greater mucous secre- was no statistical difference between them. For this reason,
tion [42]. the results were pooled. Variations were observed in the total
The protein level of the diet may be another factor to be myenteric populations with quantitative reductions in models
considered. The increase in the number of goblet cells due involving aging [14,15], diabetes [17], and caloric restriction
to a high-protein diet has been previously reported in fish [18]; furthermore, increased neuron number was noted in ex-
[43]. A reduction in their number due to a hypoproteic diet perimental models of denervation [16] and obesity induced
has been found in rats [44], and maintenance of goblet cell by MSG [12].
number independent of protein content in the diet has been The maintenance of myenteric neuron number observed in
found in mice [45]. The cafeteria diet used in the present the present obesity models, although apparently divergent,
study was characterized as hypoproteic with a low-fiber con- cannot be considered as being discrepant with other studies
tent, leading to lower mucous production. Two factors may [12] that reported a larger neuron number in the ileum of
have contributed to the reduction in goblet cell population rats that became obese due to MSG administration. These
observed in the SCa and TCa groups. previous studies attributed the difference to the lower

8. C. R. Scoaris et al. / Nutrition 26 (2010) 312–320 319
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