In the present study we report that the undernourished rats during fetal life submitted to a neonatal recovery regime had a return to normal metabolic and physical growth conditions during the nursing period, and that their food consumption was more than controls, from weaning until adult age. However, in spite of the metabolic and physical recovery of the gestational undernourished rats, the activity of brain tryptophan-5-hydroxylase (TrpOH) remained elevated accompanied by an increase in the concentration of the neurotransmitter, serotonin (5-HT). Besides, the current observation confirms and extends to previous results, that an increase in brain 5-HT content, in L-tryptophan (L-Trp) concentration and in the activity of TrpOH, in undernourished rats occurs not only during gestation and lactation periods, but it lasts until adulthood. The increase in the activity of TrpOH observed during the fetal stage and continuing to postnatal life in undernourished rats seems to be secondary to an increased transport of plasma L-Trp to their brain. These findings suggest the hypothesis that the mechanism of accelerated synthesis of brain 5-HT in the adult nutritionally recovered animals, may not depended on the increased availability of free plasma L-Trp observed in the undernourished rats, but might be due to a specific change in the TrpOH structure, supported by previous results showing different kinetic and phosphorylating properties. Our observations also suggest that the increased food intake in the recovered animals imply changes in feeding behavior possibly related to the altered serotonin brain neurotransmission.
Keywords: Brain; Nutritional recovery; Serotonin; Tryptophan-5-hydroxylase; Undernourishment.