Could Preference for Palatable Foods in Neonatally Handled Rats Alter Metabolic Patterns in Adult Life?

Abstract

ABSTRACT:Previous studies indicate that, in adulthood, neonatally handled rats consume more sweet food than nonhandled rats. The aim of the present study was to assess the effects of the chronic exposure to a palatable diet (chocolate) in adult neonatally handled rats. We measured the consumption of foods (standard lab chow and chocolate), body weight gain, abdominal fat deposition, and levels of plasma lipids, glucose, insulin, and corticosterone in adult neonatally handled (10 min/d, first 10 d of life) and nonhandled rats. We found an increased intake of chocolate in handled rats, but this consumption decreased over time. Handled male animals exhibited higher body weight, higher caloric efficiency, and lower triglyceride levels. Nonhandled females that were exposed long-term to the highly caloric diet had increased abdominal fat deposition compared with handled females. Overall female rats had increased abdominal fat deposition, higher total cholesterol and glucose levels, and lower insulin in comparison with males. Interestingly, chocolate consumption diminished the weight of the adrenal glands in both handled and nonhandled animals. These findings suggest that neonatal handling induces a particular metabolic pattern that is sex specific. M other-infant interactions have an important influence on the programming of both behavioral (1,2) and metabolic patterns (2,3) in the offspring, which can last into adulthood. In mammals, the mother is the main environmental stimulus and provider for the infant, and maternal care has profound, long-lasting intergenerational effects in rats (4,5) and humans (6).Some experimental approaches have been developed to study this interaction. One of them is neonatal handling, a brief, repeated, and apparently innocuous separation from the mother in the neonatal period. Neonatal handling modulates the development of the hypothalamopituitary-adrenal axis (HPA) axis and is associated in adulthood with decreased stress reactivity (7,8) and increased ingestion of palatable food (9).Glucocorticoids are implicated in the development of eating disorders (10,11); they modulate in part the salience of palatable food intake and influence abdominal fat distribution (12).In addition, chronic glucocorticoid exposure is associated with several features of metabolic syndrome (13-15). Because neonatal handling leads to a differential functioning of the HPA axis and also affects feeding behavior, it is possible that these rats may exhibit special adaptations in the face of specific challenges, such as long-term exposure to a hyperpalatable diet.The aim of this study was to verify the effects of a long-term exposure during adulthood to a highly palatable, highly caloric diet (chocolate) in neonatally handled rats. Food consumption, body weight, and abdominal fat distribution were measured. Blood plasma was assayed for glycemia, plasma insulin, lipids, and corticosterone levels. Our hypothesis was that neonatal handling is associated with a differential pattern of feeding and weight gain and possibl...

Early life experience alters behavioral responses to sweet food and accumbal dopamine metabolism

“…These animals also ingest more palatable pellets than controls when exposed to them either in a test apparatus (Silveira et al, 2004, 2008; Benetti et al, 2007) or in the homecages (Silveira et al, 2006), without differences in the consumption of regular lab chow or fiber pellets. However, satiety to sweet food seems to be adequate in neonatally handled rats (Silveira et al, 2006).…”

“…However, when exposed to predators, handled animals may be less fearful and therefore more vulnerable than their non‐handled counterparts (Padoim et al, 2001). Concerning feeding behavior, neonatally handled animals seem to be less prone to suffer the metabolic consequences of being exposed chronically to a highly palatable diet (Benetti et al, 2007). However, it remains to be established if the concomitant exposure to different types of palatable food would affect these animals in a different way in comparison to non‐handled ones.…”

Neonatal handling: An overview of the positive and negative effects

“…This ontogenetic pattern corroborates the clinical literature, which suggests that eating disorders like anorexia nervosa and bulimia emerge after puberty (Fairburn & Harrison, 2003). Furthermore, neonatal handling seems to affect only a few metabolic parameters: plasma levels of ghrelin and triglycerides are decreased, but there is no change in insulin, leptin, glucose, or cholesterol levels (Benetti et al, 2007; Silveria et al, 2006). These studies indicate that the neonatal handling model provides an approach for understanding mechanisms underlying the enduring consequences of early experience on the individual’s responses to food.…”

Effects of a chronic exposure to a highly palatable diet and its withdrawal, in adulthood, on cerebral Na+,K+‐ATPase and plasma S100B in neonatally handled rats

“…In addition, neonatally handled rats exhibit increased consumption of palatable foods during acute exposure to this type of food (Silveira et al, 2006; da Silva Benetti et al, 2007). In our previous studies, we described a protective influence of neonatal handling on abdominal fat deposition (da Silva Benetti et al, 2007) in female rats after a chronic exposure to a highly palatable, highly caloric diet. Therefore, it was suggested that a specific metabolic response to chronic highly caloric diets could protect handled females from the harmful effects of this environmental challenge in adulthood.…”