Unilateral hypothalamic lesion results in compensatory sprouting of contralateral magnocellular neurosecretory axons in the rat neural lobe
Year: 1989
Type: dissertation
Abstract: Sprouting in the magnocellular neurosecretory system was investigated using a unilateral hypothalamic knife-cut of the hypothalamo-neurohypophysial tract to partially denervate the rat neural lobe (NL).Densitometrie, stereometric and ultrastructural methods were utilized to demonstrate the compensatory response to denervation in this system.Quantitative immunocytochemical analysis of vasopressin levels in the NL demonstrated a transient reduction by 10 days post-surgery with a subsequent trend toward recovery reaching 88% of normal 3 months following surgery.Measures of neural lobe cross-sectional area demonstrated a similar trend with an initial reduction in size followed by a recovery to normal cross-sectional area over an identical time course.Morphometric measurement of contralateral supraoptic (SON) and paraventricular (PVN) magnocellular neurons known to project to the neural lobe revealed a persistent hypertrophy of both soma and cell nuclei in both areas throughout the post-surgical period examined.Ultrastructural investigations revealed a reduction in axon number in the NL following surgery which paralleled the decrease in vasopressin immunoreactivity and cross-sectional area.This reduction was followed by a partial recovery of axon number closely correlated with the increase in normal vasopressin immunoreactivity and size of the neural lobe.These results suggest that contralateral magnocellular vasopressinergic efferents will undergo compensatory sprouting as a result of partial denervation of the neural lobe.This thesis is dedicated to the late George Michael Carson whose unbounded friendship and undaunted spirit will forever provide a source of strength to those who knew and loved him.
Author: John A. Watt
Language: English
Subfield: Social Psychology
Field: Psychology
Domain: Social Sciences
Open Access status: green
OpenAlex ID: W138660689