Undernutrition and postnatal development of transcriptional activity in the rat medial mamillary nucleus (hypothalamus)

This paper aims to examine the effects of food restriction during gestation and lactation regarding the neuronal rRNA synthesis activity. In order to evaluate this activity, the distribution of the neuronal population was quantified on the basis of the argyrophilic nucleolar organizer region (Ag-NOR) numbers stained with silver nitrate. The CNS region chosen was the medial mamillary nucleus belonging to the mamillary bodies (posterior hypothalamus) of the rat, because of the unclear affectation of non-cortical regions by malnutrition and due to its implication in emotional behavior. The control group was made up of rats of 7, 14, 21 and 30 days of age and the undernourished group of animals of the same ages whose mothers received a restrictive diet during gestation and lactation. The results indicate that the distribution of neurons with one Ag-NOR increases with age while the neuron population with more than one clearly decreases with age. Our results show an overall decrease of the neuronal biosynthetic needs with age. No significant effect of undernutrition was found regarding the Ag-NOR distribution in any of the ages studied. In summary, our paper remarks the accuracy of a novel technique used to study the effects of malnutrition, as an indirect index of protein biosynthesis, which is simple, affordable and rapid as compared to the conventional autoradiographic studies of radioactive amino-acid incorporation for the same purpose.