Maternal prolactin inhibition causes changes in leptin at 22- and 30-day-old pups

Does early weaning shape future endocrine and metabolic disorders? Lessons from animal models

Obesity and its complications occur at alarming rates worldwide. Epidemiological data have associated perinatal conditions, such as malnutrition, with the development of some disorders, such as obesity, dyslipidemia, diabetes, and cardiovascular diseases, in childhood and adulthood. Exclusive breastfeeding has been associated with protection against long-term chronic diseases. However, in humans, the interruption of breastfeeding before the recommended period of 6 months is a common practice and can increase the risk of several metabolic disturbances. Nutritional and environmental changes within a critical window of development, such as pregnancy and breastfeeding, can induce permanent changes in metabolism through epigenetic mechanisms, leading to diseases later in life via a phenomenon known as programming or developmental plasticity. However, little is known regarding the underlying mechanisms by which precocious weaning can result in adipose tissue dysfunction and endocrine profile alterations. Here, the authors give a comprehensive report of the different animal models of early weaning and programming that can result in the development of metabolic syndrome. In rats, for example, pharmacological and nonpharmacological early weaning models are associated with the development of overweight and visceral fat accumulation, leptin and insulin resistance, and neuroendocrine and hepatic changes in adult progeny. Sex-related differences seem to influence this phenotype. Therefore, precocious weaning seems to be obesogenic for offspring. A better understanding of this condition seems essential to reducing the risk for diseases. Additionally, this knowledge can generate new insights into therapeutic strategies for obesity management, improving health outcomes.

Locomotor response to acute nicotine in adolescent mice is altered by maternal undernutrition during lactation

Undernutrition during brain development causes long lasting alterations in different neurotransmitter systems that may alter responses to psychoactive drugs. Despite the recognized effects of early undernutrition on the cholinergic system, no evidence that demonstrates the influence of this insult on nicotine susceptibility has been reported. We investigated the effects of protein/calorie restriction during lactation on the susceptibility to nicotine in adolescent mice. Dams were randomly assigned to one of the following groups: Control (C, 20 litters)--free access to standard laboratory diet (23% protein); Protein Restricted (PR, 12 litters)--free access to a isoenergetic, 8% protein diet; Calorie Restricted (CR, 12 litters)--access to standard laboratory diet in restricted quantities (mean ingestion of PR: pair-fed group). Undernutrition extended from postnatal day 2 (PN2) to weaning (PN21). At PN30, animals either received an i.p. injection of nicotine (0.5mg/Kg) or saline and were immediately placed in open field (OF). After the OF, adrenal glands and serum were collected for the analyses of stress-related endocrine parameters and leptin concentration. PR and CR offspring showed less body mass gain and visceral fat mass. PR offspring presented reduced serum leptin concentration. In the OF, nicotine increased locomotor activity of C and PR, but not of CR. CR and PR offspring showed decreased adrenal catecholamine content, which was not dependent on nicotine exposure. Our results indicate that early undernutrition interferes with nicotine-elicited locomotor effects in adolescent mice and suggest that endocrine parameters alterations in malnourished animals do not influence the behavioral response to nicotine.