Dopaminergic inhibition of pituitary beta-endorphin-like immunoreactivity secretion in the rat.
A pharmacologic approach was used to examine the possible role of dopamine neurons in the regulation of pituitary beta-endorphin-like immunoreactivity (beta-END-LI) secretion in the rat. Blockade of dopamine receptors by haloperidol or pimozide treatment evoked dose- and time-related increases in plasma levels of beta-END-LI. Physical immobilization increased circulating beta-END-LI six-fold and pretreatment with dopamine receptor agonists (bromocriptine or pergolide) significantly attenuated this rise without affecting plasma beta-END-LI levels in non-stressed animals. Dopaminergic drugs and immobilization produced similar effects on circulating PRL as on beta-END-LI. However, the magnitude of change in levels of PRL was generally greater than the change in beta-END-LI. The present findings suggest that dopaminergic neurons inhibit the release of pituitary beta-END-LI as well as PRL in the rat.
D000818:Animals; D004723:Endorphins / Q000032:analysis / Q000378:metabolism*; D006220:Haloperidol / Q000494:pharmacology; D008297:Male; D010868:Pimozide / Q000494:pharmacology; D010902:Pituitary Gland / Q000378:metabolism*; D011388:Prolactin / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000187:drug effects / Q000502:physiology*; D001615:beta-Endorphin
D004723:Endorphins; D011954:Receptors, Dopamine; D010868:Pimozide; D001615:beta-Endorphin; D011388:Prolactin; D006220:Haloperidol