Neonatal environmental intervention alters the vulnerability to the metabolic effects of chronic palatable diet exposure in adulthood.

Previous studies have demonstrated that early environmental interventions influence the consumption of palatable food and the abdominal fat deposition in female rats chronically exposed to a highly caloric diet in adulthood. In this study, we verified the metabolic effects of chronic exposure to a highly palatable diet, and determine the response to its withdrawal in adult neonatally handled and non-handled rats. Consumption of foods (standard lab chow and chocolate), body weight gain, abdominal fat deposition, plasma triglycerides, and leptin, as well as serum butyrylcholinesterase (BuChE), and cerebral acetylcholinesterase (AChE) activities were measured during chronic chocolate exposure and after deprivation of this palatable food in female rats exposed or not to neonatal handling (10 minutes/day, 10 first days of life). Handled rats increased rebound chocolate consumption in comparison to non-handled animals after 1 week of chocolate withdrawal; these animals also decreased body weight in the first 24 hours but this effect disappeared after 7 days of withdrawal. Chocolate increased abdominal fat in non-handled females, and this effect remained after 30 days of withdrawal; no differences in plasma leptin were seen after 7 days of withdrawal. Chocolate also increased serum BuChE activity in non-handled females, this effect was still evident after 7 days of withdrawal, but it disappeared after 30 days of withdrawal. Chocolate deprivation decreased cerebral AChE activity in both handled and non-handled animals. These findings suggest that neonatal handling modulates the preference for palatable food and induces a specific metabolic response that may be more adaptive in comparison to non-handled rats.

Effects of exposure to a cafeteria diet during gestation and after weaning on the metabolism and body weight of adult male offspring in rats.

In the present study, we investigated whether maternal exposure to a cafeteria diet affects the metabolism and body composition of offspring and whether such an exposure has a cumulative effect during the lifetime of the offspring. Female rats were fed a control (CON) or a cafeteria (CAF) diet from their own weaning to the weaning of their offspring. At 21 d of age, male offspring were divided into four groups by diet during gestation and after weaning (CON-CON, CON-CAF, CAF-CON and CAF-CAF). Blood was collected from dams (after weaning) and pups (at 30 and 120 d of age) by decapitation. CAF dams had significantly greater body weight and adipose tissue weight and higher concentrations of total cholesterol, insulin and leptin than CON dams (Student's t test). The energy intake of CAF rats was higher than that of CON rats regardless of the maternal diet (two-way ANOVA). Litters had similar body weights at weaning and at 30 d of age, but at 120 d, CON-CAF rats were heavier. At both ages, CAF rats had greater adipose tissue weight than CON rats regardless of the maternal diet, and the concentrations of TAG and cholesterol were similar between the two groups, as were blood glucose concentrations at 30 d of age. However, at 120 d of age, CAF rats were hyperglycaemic, hyperinsulinaemic and hyperleptinaemic regardless of the maternal diet. These findings suggest that maternal obesity does not modulate the metabolism of male offspring independently, modifying body weight only when associated with the intake of a cafeteria diet by the offspring.

Satiety assessment in neonatally handled rats.

We have previously demonstrated that neonatal handling increases sweet food ingestion. In the present study, we examined whether food intake, using different kinds of food, is altered in neonatally handled animals, with or without inducing satiety using a sucrose solution. Abdominal fat, glycemia and hormones linked to appetite including leptin, ghrelin and insulin were also measured. We tested palatable food consumption in the homecage to verify whether environmental cues could influence ingestion. Nests of Wistar rats were either (1) non-handled or (2) handled (10 min/day). Handling was performed on days 1-10 after birth. When adults, rats were habituated to sweet food (Froot Loops, Kellogg's) and to palatable fiber pellets (Fiber One), Nestlé). Sweet food consumption was increased in the neonatally handled group, when tested in the homecage, and also in the satiety experiment. These rats displayed a satiety curve when compared to the control group, which ate less but constantly. Handled rats exposed to a sucrose solution decreased sweet food ingestion, which did not occur in the control group. When exposed to a food with complex carbohydrates, these differences disappeared. There were no differences in body weight, abdominal fat or in glycemia, as well as no differences in plasma levels of insulin or leptin. However, ghrelin was decreased in neonatally handled rats. Neonatally handled rats demonstrated an increased consumption of sweet food, satiety responses to sucrose, as well as decreased levels of plasma ghrelin. It is possible that signaling mechanisms related to satiety, both peripherally and/or centrally may contribute to these behavioral findings.