The effects of protein deprivation on the nucleus raphe dorsalis: A morphometric golgi study in rats of three age groups

Abstract

In a previous study we identified 3 cell types in the nucleus raphe dorsalis (NRD): fusiform, multipolar and ovoid. In the present study, we have investigated the effect of an 8% casein diet on these 3 cell types using quantitative techniques on rapid Golgi-impregnated neurons from rats of 3 different ages: 30, 90 and 220 days. Major and minor axes of the cell body and dendritic diameter were unaffected and primary dendritic linear extent was only slightly affected by the diet. All 3 cell types in control rats showed an increase in synaptic spines on both primary and secondary dendrites between 30 and 90 days followed by a decrease for all 3 of the cell types at 220 days. Protein-deprived rats failed to show these age-related changes. Other parameters of comparison showed clear differences between the 3 cell types. These differences could be readily seen when total synaptic spine input to the primary and secondary dendrites was calculated from the data on dendritic number, linear extent and spine density. When viewed in this way the fusiform and ovoid cells show either little change or a decreased synaptic input at all ages, while the presumed serotonergic multipolar cells showed an increase. This is in agreement with neurochemical studies in these rats showing increased levels of this biogenic amine in protein malnourished rats.