Growth hormone modulates serum cholinesterase.

Adult male rats have lower serum cholinesterase activity levels than adult female rats and hypophysectomized male rats have higher activity levels than sham-operated males (similar to control females). GH administered to hypophysectomized male rats abolishes the effect of hypophysectomy on serum cholinesterase. Adult male rats treated neonatally with monosodium L-glutamate to induce arcuate nucleus lesions of the hypothalamus have higher serum cholinesterase activities and decreased serum GH concentrations. GH administered to these male rats results in decreased serum cholinesterase activities. These experiments demonstrate that GH is a negative modulator of serum cholinesterase in the male rat.