Hypothalamic peptide and nutrient sensors gene expression in the hypothalamus of neonatal rat.

In the neonate, the main mediator for satiety or hunger is the information of distention or gastric contraction. Food intake controls has two types of a short-term one, based on the level of hydration, and another long-term one, dependent on the gastric stretch. The aim of this study is to evaluate the gene expression of peptides and nutrient sensors in the hypothalamus at 10 and 18 days of postnatal life. Male rats divided into groups: Fasting, Water, Milk, and Gavage.Two age groups had analyzed into 10 and 18 days. Gene expression of hypothalamic peptides, Neuropeptide Y(NPY), Agouti-related peptide(AgRP), proopiomelanocortin(POMC), cocaine-and amphetamine-regulated transcript(CART), and energy sensors mechanistic target of rapamycin(mTOR) and AMP-activated protein kinase(AMPK) in the hypothalamus was seen. During the fasting period, there was an increase in expression of AMPK seen in 10 and 18 days, also mTOR reduction. Expression of NPY, AgRP, and POMC suffered the fasting effect only at 18 days. The effect of gastric distention and energy loads, there was increased expression of AMPK at 10 and 18 days, but expression of mTOR showed only at 18 days. There was increased NPY expression at 18 days, but not at 10 days, while AgRP increased its expression at both ages. At 10 days gene expression of CART increased and POMC as well as 10-18 days. Data demonstrated a simultaneous responsiveness to hypothalamic nutrient sensing also, controlling peptide food consumption even at an early age. The mature standard of control only observed at 18 days of life.

Early life stress induced by maternal separation during lactation alters the eating behavior and serotonin system in middle-aged rat female offspring.

Stressful events occurring during early life have been related to behavioral and neurochemical disturbances. Maternal separation during the first two weeks of life is a traumatic event that strongly affects the feeding behavior and serotonergic system of the progeny in adulthood. As this system modulates the feeding behavior, the present study aimed at investigating the effects of maternal separation-induced stress on both the feeding behavior and serotonergic system of the middle-aged female rats by manipulating this system using fluoxetine, a selective serotonin transporter inhibitor. Lactating Wistar rats were separated from their litters from postnatal day 2 (PND 2) to PND 14 for 3 h in the dark phase of the circadian cycle. The maternally separated (MS) and control (C) groups were distinguished from each other based on the incidence or absence of maternal separation (early life stress). All the analyses were done on the female offspring from one-year of age. Maternal separation anticipated the satiety point in these females. This anticipation was linked to lower food intake, meal duration and meal size. These results mirrored the effects of fluoxetine in the control animals. Furthermore, maternal separation was associated with 5ht1b serotonin receptor hyperexpression in the hypothalamus. These findings demonstrate that maternal separation has long-lasting effects on the eating behavior and serotonergic system and that this system could be responsible for mediating these behavioral outcomes.

Effects of perinatal protein malnutrition and fenfluramine action on food intake and neuronal activation in the hypothalamus and raphe nuclei of neonate rats.

In neonatal rats, hunger and satiety responses occur particularly via dehydration and gastric distention, respectively. The control of food intake in newborns is yet to be fully consolidated, particularly with respect to the participation of the hypothalamic nuclei and their relationship with the serotonergic pathway. Moreover, it is unclear how the environmental stressors in early life, like undernutrition, interfere in these events. Therefore, this study examined the serotonin-system's impact on food intake in rat neonates at postnatal day (P) 10 and P18 and the manner in which protein undernutrition during pregnancy and lactation interferes in this behavior. To accomplish this, Wistar rats were used, nutritionally manipulated by a diet having two protein levels, (8% and 17%) during pregnancy and lactation, to form the Control (n=10) and Low protein groups (n=10). At 10 and 18 postnatal days pups received an acute dose of fenfluramine (3mg/kg) or saline (0.9% NaCl) and subjected to milk consumption testing and then perfused to obtain the brains for the analysis of cell activation of the immunoreactive c-Fos in the hypothalamic and raphe nuclei. At 10days a reduction in weight gain was observed in both groups. On comparison of the neuronal activation for the paraventricular nucleus, an increased activation in response to fenfluramine was observed. At 18days, the weight gain percentage differed between the groups according to the nutritional manipulation, in which the control animals had no significant change while the undernourished presented increased weight gain with the use of fenfluramine. The marking of c-Fos in response to fenfluramine in the hypothalamic and raphe nuclei revealed, an especially lower activation of the PVN, MnR and DR compared intra-group. However when evaluating the effect of undernutrition, marking activation was observed to increase in all the nuclei analyzed, in the hypothalamus and raphe. Data from this study indicate that the action of serotonin via food intake in the neonates may have been delayed by early protein undernutrition.