Influence of neonatally-administered monosodium glutamate on the neuroendocrine regulation of prolactin cell activity in adult Syrian hamsters.

The effects of MSG on PRL cell activity in hamsters was assessed by injecting either MSG (8 mg/g body weight) or saline into male and female hamsters on day 8 of the neonatal period. One-hundred and three days later, the anterior pituitaries were removed for the analysis of PRL synthesis and storage. Serum PRL levels were also determined by radioimmunoassay as an index of in vivo PRL secretion. Blood levels of PRL were decreased by 74% in female and 88% in male hamsters treated with MSG as compared with vehicle controls. In females, glutamate induced a drop in PRL storage (90%) and synthesis (82%) while in male animals glutamate caused a non-significant decrease in PRL storage (48%) and synthesis (31%) as compared with controls. These results indicate that MSG-induced arcuate nucleus lesions inhibit PRL cell activity in the hamster.