A comparative study of the effects of the pineal gland on prolactin synthesis, storage and release in male and female blind-anosmic rats.

The effect of the pineal gland on Prl synthesis, storage and release were compared in male and female rats 8 weeks after prepubertal blinding and olfactory bulbectomy. Anterior pituitary weight was reduced in blind-anosmic female and male rats. This was correlated with a decreased pituitary DNA content in male blind-anosmic rats. Pinealectomy partially reversed these effects. Prl release, as assessed by monitoring serum Prl levels, was significantly reduced in both male and female blind-anosmic rats. Pinealectomy reversed the effect in females but not males. Prl storage was estimated by measuring the levels of Prl in the anterior pituitary in vivo. Pituitary Prl content was significantly decreased in both male and female blind-anosmic rats. Pinealectomy prevented this reduction in Prl storage. Finally, Prl synthesis was evaluated by measuring the incorporation of [3H] leucine into Prl during 5 hours of pituitary incubation in vitro. Prl synthesis was decreased by 45% in blind-anosmic female rats and 34% in blind-anosmic male rats. Once again these effects were due to the pineal because pinealectomy fully ameliorated the influences of blinding and olfactory bulbectomy on Prl synthesis. From these data we conclude that the pineal inhibits Prl synthesis, storage and release in both female and male blind-anosmic rats.