Summary
In a primary monolayer cell culture of the anterior pituitary from mature male rats
the effects of exogenous rPrl (rPrl exog.) and endogenously secreted rPrl (rPrl endog.)
on basal and LHRH stimulated LH secretion were investigated. In pilot studies basal
Prl- and LH secretion as well as influence of various LHRH concentrations (10-1-10+3ng/ml) on Prl- and LH release were observed. The influence of exogenous rPrl was studied
at various concentrations (50-500 ng/ml) and with preincubation periods of 2 hrs and
6 hrs before starting LHRH stimulation. The dopamine agonist bromocriptine and the
dopamine antagonist sulpirid were preferentially used to prove physiologic function
of the cell system presented.
Basal LH secretion started after a delay of 3 hrs, whereas basal Prl secretion began
immediately showing a linear rise for 9 hrs. LHRH stimulation resulted in a non-linear
dose and time dependent LH secretion. LHRH showed no influence on endogenous Prl (rPrl
endog.) secretion of the mammotroph cells.
Exogenous Prl (rPrl exog.) did not affect spontaneous Prl release excluding ultra
short loop inhibition in this cell system. Furthermore, exogenous Prl had no effect
on either basal or LHRH stimulated LH secretion even after a preincubation period
of up to 6 hrs and at concentrations generally observed for prolactin secreting tumors.
Bromocriptine suppressed endogenous Prl release and did not affect LH secretion. Sulpirid
had no influence on either Prl or LH secretion.
The present data supply further evidence that there is no direct interaction between
Prl and LH secretion at the pituitary level. Autoregulation of Prl release (ultra
short loop inhibition) could not be demonstrated in this cell system.
Key-Words
Prolactin
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LH
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Anterior Pituitary Monolayer Cell Cultures
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Male Rat
