AJP - Endocrinology and Metabolism, Vol 245, Issue 3 261-E265, Copyright © 1983 by American Physiological Society
Increase in pituitary dopaminergic receptors after monosodium glutamate treatment
M. L. Heiman and N. Ben-Jonathan
We investigated whether a decrease in arcuate nucleus dopamine (DA) levels
resulting from neonatal treatment with monosodium glutamate (MSG) affects
the anterior pituitary DA receptors in adult male rats. MSG treatment
resulted in a significant reduction in medial basal hypothalamic (MBH) DA
levels, no change in its norepinephrine (NE) and epinephrine (E)
concentrations, and a marked increase in circulating prolactin (PRL).
Scatchard analyses of DA binding characteristics to anterior pituitary
membranes using [3H]spiperone revealed linear plots, suggesting a single
class of high-affinity, low-capacity binding sites. The DA binding capacity
was significantly higher in MSG-treated rats than in controls with no
change in affinity. The data indicate that anterior pituitary DA receptors
change in accordance with altered physiological conditions. The increase in
the number of DA receptors following destruction of the arcuate nucleus is
probably a direct effect of reduced DA levels reaching the anterior
pituitary gland.
