The effect of aging on prolactin secretion in rat pituitary monolayer culture

Abstract

A high basal rate of prolactin (PRL) secretion (.16±.03 μg/well/hr) was produced for over four weeks by pre-confluent male rat pituitary monolayer cell cultures. When the media was changed, a rapid release of microgram quantities of PRL occurred followed by a return to the basal PRL secretory rate by seven hours. Theophylline (3.8×10 −3M), but not dibutyrl cAMP (1×10 −3M), produced a significant (p<.02) increase in PRL secretion, and simultaneous addition of these agents potentiated the PRL secretory rate. TRH (2×10 −8M) had no effect on PRL release by six hours, whereas dopamine (4.9×10 −5M) produced a significant suppression (p<.002) of PRL secretion. In addition, the effects of theophylline, TRH, and dopamine on PRL secretion were similar in cultures of various ages. Ovine prolactin in concentrations up to 50 μg per ml produced no change in PRL secretion during 72 hours of incubation suggesting that PRL feedback control of its own secretion may be transmitted via the hypothalamus. These studies show that a high rate of PRL secretion can be maintained by pre-confluent monolayer cultures for extended periods of time, permitting repeated experimentation on the same wells.