The Journal of Neuroscience, December 15, 1998, 18(24):10735-10748
Perinatal Gonadectomy Exerts Regionally Selective, Lateralized
Effects on the Density of Axons Immunoreactive for Tyrosine Hydroxylase
in the Cerebral Cortex of Adult Male Rats
M. F.
Kritzer
Department of Neurobiology and Behavior, State University of New
York at Stony Brook, Stony Brook, New York 11794-5230
The catecholamine innervation of the cerebral cortex is essential
for its normal operations and is implicated in cortical dysfunction in
mental illness. Previous studies in rats have shown that the
maturational tempo of these afferents is highly responsive to changes
in gonadal hormones. The present findings show that perinatal hormone
manipulation also has striking, region- and hemisphere-specific
consequences for cortical catecholamines in adulthood.
The effect of perinatal gonadectomy on catecholamines was examined in
representative sensory, motor, and association cortices of adult male
rats by combining hormone manipulation with immunocytochemistry for
tyrosine hydroxylase, a rate-limiting enzyme in catecholamine biosynthesis. Qualitative and quantitative comparison of
immunoreactivity in rats perinatally gonadectomized or sham-operated
revealed complex changes in gonadectomized subjects; in cingulate
cortex, TH immunoreactivity was strongly and bilaterally diminished, in
sensory and motor cortices, axon density was decreased in left
hemispheres, but was minimally affected on the right, and in a premotor
cortex, gonadectomy was without significant effect in either
hemisphere. Corresponding analyses in gonadectomized rats supplemented
with testosterone revealed a protective influence, albeit one in which TH immunoreactivity so showed regional and hemispheric variability in
responsiveness to hormone replacement. These complex patterns of TH
sensitivity suggest highly asymmetric hormone stimulation of cortical
catecholamines. Such discriminative action may contribute to sex
differences in the functional maturation and lateralization of the
cortex and may also have bearing on disorders such as dyslexia, which
show sexual dimorphisms, and in which functional laterality of the
cortex may be particularly at issue.
Key words:
dopamine; neocortex; estrogen; androgen; tyrosine
hydroxylase; cerebral hemisphere
Copyright © 1998 Society for Neuroscience 0270-6474/98/182410735-14$05.00/0