DISTRIBUTION OF CATECHOLAMINE-SYNTHESIZING ENZYMES AND SOME NEUROPEPTIDES IN THE MEDIAN EMINENCE-ARCUATE NUCLEUS COMPLEX (MEARC) OF THE IMMATURE FEMALE PIG

The presence of the catecholamine-synthesizing enzymes tyrosine hydrox ylase (TH) and dopamine-beta-hydroxylase (D beta H) and some neuropept ides, including neuropeptide Y (N beta Y), Leu(5)-enkephalin (LENK), v asoactive intestinal polypeptide (VIP), calcitonin gene-related peptid e (CGRP), substance P (SP), galanin (GAL) and somatostatin (SOM) was i nvestigated in nerve fibres and perikarya of the median eminence-arcua te nucleus complex (MEARC) of the sexually immature female pigs by mea ns of the immunohistochemical avidin-biotin complex method. Although i mmunoreactivities to all the studied substances were found in nerve fi bres of the porcine MEARC, there were differences in the distribution and density of particular subsets of nerve fibres within the complex. While loose D beta H-immunoreactive (D beta H-IR) and dense TH-, NPY- and VIP-IR nerve meshworks occurred predominantly in the internal laye r of the MEARC, nerve fibres immunoreactive to TH, CGRP, SOM, SP and L ENK were more numerous in the external than in the internal layer of t he median eminence (ME). Numerous TH, D beta H-, NPY-, VIP, SP- and CG RP-IR perivascular nerve fibres were also observed within both layers of the median eminence. There were also differences in the distributio n of a particular subset of neurons within the porcine MEARC: NPY-, VI P, GAG, SP- and TH-IR (but not D beta H-IR) perikarya were found in th e arcuate nucleus, while in the median eminence only subpopulations of NPY-, VIP and GAL-IR neurons were observed.