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 gest ation and lactation regarding the neuronal rRNA synthesis activity. In order to evaluate this activity, the distribution of the neuronal pop ulation was quantified on the basis of the argyrophilic nucleolar orga nizer region (Ag-NOR) numbers stained with silver nitrate. The CNS reg ion chosen was the medial mamillary nucleus belonging to the mamillary bodies (posterior hypothalamus) of the rat, because of the unclear af fectation of non-cortical regions by malnutrition and due to its impli cation 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 gest ation and lactation. The results indicate that the distribution of neu rons with one Ag-NOR increases with age while the neuron population wi th more than one clearly decreases with age. Our results show an overa ll decrease of the neuronal biosynthetic needs with age. No significan t effect of undernutrition was found regarding the Ag-NOR distribution in any of the ages studied. In summary, our paper remarks the accurac y of a novel technique used to study the effects of malnutrition, as a n 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. (C) 1997 El sevier Science Inc.