Long-term Consequences of Early Undernourishment on the Activation of Brain Serotonin Synthesis in the Rat: Effect of Nutritional Recovery during the Period of Nursing

Transgenerational effects of caloric restriction on appetite: a meta-analysis

Maternal undernutrition can result in significant alterations to the post-natal offspring phenotype, including body size and behaviour. For example, maternal food restriction has been implicated in offspring hyperphagia, potentially causing increased weight gain and fat accumulation. This could result in obesity and other adverse long-term health effects in offspring. We investigated the link between maternal caloric restriction during gestation and offspring appetite by conducting the first meta-analysis on this topic using experimental data from mammalian laboratory models (i.e. rats and mice). We collected 89 effect sizes from 35 studies, together with relevant moderators. Our analysis revealed weak and statistically non-significant overall effect on offspring's appetite. However, we found that lower protein content of restricted diets is associated with higher food intake in female offspring. Importantly, we show that a main source of variation among studies arises from whether, and how, food intake was adjusted for body mass. This probably explains many of the contradictory results in the field. Based on our results, we recommend using allometric scaling of food intake to body mass in future studies.

Serotonin and dopamine in the hypothalamus of control and malnourished mother rats during pregnancy and lactation and body composition of their offspring

OBJECTIVE

To determine concentrations of serotonin and dopamine in the hypothalamus of undernourished rats and controls during pregnancy and lactation and body composition of their offspring.

METHODS

Malnourished rats along with control rats were used during pregnancy and lactation. At birth of their offspring, control mothers nursed their young and malnourished rats and the undernourished mothers nursed their offspring and control pups. On days 5, 10, 15, and 21 of lactation (at the beginning and end of a feeding), L-tryptophan (L-Trp)-free, bound and total, plasma prolactin (PRL) and milk composition were determined. Serotonin and dopamine were measured in the hypothalamus. Body composition of offspring was determined.

RESULTS

Increase of free L-Trp was confirmed in undernourished mothers. Furthermore, hypothalamic serotonin was elevated at the start of suckling and decreased at termination. There was also a decrease in dopamine in the hypothalamus at the beginning and end of suckling followed by an increase of plasma PRL that was greater in control mothers who breastfed malnourished offspring. Interestingly, undernourished offspring consumed more milk and showed a clear recovery of body composition with accumulation of body fat.

DISCUSSION

Changes observed in hypothalamic neurotransmitters appear to be closely related to nutritional status and to the response and control of PRL production, possibly to adapt the offspring to the metabolic changes. It was also confirmed that on-demand feeding of undernourished offspring is the main factor involved in nutritional recovery and a predisposition to overweight in the recovered undernourished animals.

Serotonergic receptors in the brain of in utero undernourished rats

In this study, we report that 5-HT(1A) receptors are already present in fractions of axonal growth cones, from the normal rat fetal brain (E-17). Also, in utero undernourished (UN) rat pups at birth show a noteworthy enhancement in the B(max) of [3H]5-hydroxytryptamine (5-HT) and [3H]8-hydroxy-(2-N,N-dipropilamin)-tetralin (([3H])8-OH-DPAT), in the brainstem and cerebral cortex up to the second week after birth. Afterwards, there is a significant decrease in the binding of these ligands. [125I]Cyanopindolo binding in the cerebral cortex only showed a decrease in the same period. An elevation of brain serotonin in both regions was also present. These findings together, suggest that the mechanisms of regulation of serotonergic receptors' expression during the period studied, may not depend on the amount of neurotransmitter in the synaptic cleft, because in the early UN brain it would be expected only a lower receptor's density due to the chronic serotonin increase. On this basis, we propose that developmental activation of brain serotonin biosynthesis observed in early UN animals may disrupt the mechanism regulating the expression of 5-HT receptors during development.

A randomised, controlled study of dietary intervention in autistic syndromes

Impaired social interaction, communication and imaginative skills characterize autistic syndromes. In these syndromes urinary peptide abnormalities, derived from gluten, gliadin, and casein, are reported. They reflect processes with opioid effect. The aim of this single blind study was to evaluate effect of gluten and casein-free diet for children with autistic syndromes and urinary peptide abnormalities. A randomly selected diet and control group with 10 children in each group participated. Observations and tests were done before and after a period of 1 year. The development for the group of children on diet was significantly better than for the controls.

Reports on dietary intervention in autistic disorders

Autism is a developmental disorder for which no cure currently exists. Gluten and/or casein free diet has been implemented to reduce autistic behaviour, in addition to special education, since early in the eighties. Over the last twelve years various studies on this dietary intervention have been published in addition to anecdotal, parental reports. The scientific studies include both groups of participants as well as single cases, and beneficial results are reported in all, but one study. While some studies are based on urinary peptide abnormalities, others are not. The reported results are, however, more or less identical; reduction of autistic behaviour, increased social and communicative skills, and reappearance of autistic traits after the diet has been broken.