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Stimulation and Inhibition of Prolactin Release by Prolactin‐Releasing Peptide in Rat Anterior Pituitary Cell Aggregates
Author(s) -
Swinnen E.,
Boussemaere M.,
Denef C.
Publication year - 2005
Publication title -
journal of neuroendocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.062
H-Index - 116
eISSN - 1365-2826
pISSN - 0953-8194
DOI - 10.1111/j.1365-2826.2005.01313.x
Subject(s) - prolactin , medicine , endocrinology , anterior pituitary , prolactin cell , stimulation , pertussis toxin , receptor , hormone , dopamine , chemistry , thyrotropin releasing hormone , biology , g protein
Although the G‐protein coupled receptor GPR10 is highly expressed in the anterior pituitary, the action of its ligand prolactin‐releasing peptide‐31 (PrRP) in this tissue is controversial. The present study examined the acute effect of this peptide on prolactin secretion in perifused rat pituitary reaggregate cell cultures from adult male rats. PrRP readily and dose‐dependently stimulated prolactin release at concentrations of 10 and 100 n M , although with a magnitude several times lower than that of thyrotropin‐releasing hormone. Surprisingly, PrRP inhibited prolactin release at 0.1 and 1 n m in a pertussis toxin‐sensitive manner. Inhibition was markedly favoured by long‐term culture. Stimulation and inhibition were differentially affected by the presence of hormones during culture: dexamethasone favoured the inhibitory effect and decreased the magnitude of the stimulatory effect, while oestradiol and triiodothyronine strongly reduced stimulation, as well as inhibition. PrRP, even at 1 n m , counteracted the inhibition of prolactin release by dopamine. There was no effect of PrRP on growth hormone release in aggregates cultured either in the absence or presence of hormones. The present results confirm the prolactin‐releasing capacity of PrRP at nanomolar doses and reveal a hitherto unrecognized inhibitory activity of this peptide. Furthermore, dopamine inhibition of prolactin release is antagonized by PrRP, irrespective of the PrRP dose.