Morphometric characteristics of Neuropeptide Y immunoreactive neurons of human cortical amygdaloid nucleus

Abstract

Cortical amygdaloid nucleus belongs to the corticomedial part of the amygdaloid complex. In this nucleus there are neurons that produce neuropeptide Y. This peptide has important roles in sleeping, learning, memory, gastrointestinal regulation, anxiety, epilepsy, alcoholism and depression. We investigated morphometric characteristics (numbers of primary dendrites, longer and shorter diameters of cell bodies and maximal radius of dendritic arborization) of NPY immunoreactive neurons of human cortical amygdaloid nucleus on 6 male adult human brains, aged 46 to 77 years, by immunohistochemical avidin-biotin technique. Our investigation has shown that in this nucleus there is a moderate number of NPY immunoreactive neurons. 67% of found neurons were nonpyramidal, while 33% were pyramidal. Among the nonpyramidal neurons the dominant groups were multipolar neurons (41%--of which 25% were multipolar irregular, and 16% multipolar oval). Among the pyramidal neurons the dominant groups were the neurons with triangular shape of cell body (21%). All found NPY immunoreactive neurons (pyramidal and nonpyramidal altogether) had intervals of values of numbers of primary dendrites 2 to 6, longer diameters of cell bodies 13 to 38 microm, shorter diameters of cell bodies 9 to 20 microm and maximal radius of dendritic arborization 50 to 340 em. More than a half of investigated neurons (57%) had 3 primary dendrites. The other researchers did not find such percentage of pyramidal immunoreactive neurons in this amygdaloid nucleus. If we compare our results with the results of the ather researchers we can conclude that all pyramidal NPY immunoreactive neurons found in this human amygdaloid nucleus belong to the class I of neurons, and that all nonpyramidal NPY immunoreactive neurons belong to the class II of neurons described by other researchers. We suppose that all found pyramidal neurons were projectional.