Rat anterior pituitary cells maintained on artificial capillaries: responses of thyrotrophs and lactotrophs to depolarization, TRH and dopamine.
Rat anterior pituitary cells have been maintained over an 18-day period in a perfusion system designed around artificial capillaries. Using novel methodology the cells have been visualized by light microscopy and appear as aggregates, closely attached to and sometimes stretching around the capillaries. Their morphology is consistent with previous histology at the level of light microscopy. The techniques described are compatible with immunohistochemistry and electron microscopy. The functional integrity of thyrotrophs and lactotrophs maintained in the system has been examined by measuring the dynamics of TSH and PRL secretion in response to depolarization, TRH and dopamine (DA). TSH and PRL were significantly and reproducibly released by TRH over a 7-day period. On each day the release was dose-dependent with a threshold of at least 28 pg. Qualitatively the responses were rapid in onset (within minutes) for both hormones. Similar responses were measured in response to high K+ depolarization. Basal secretion of TSH and PRL was rapidly and significantly inhibited by DA in a dose-dependent manner (ED50 20 +/- 25 nM for TSH and 70 +/- 40 nM for PRL). Inhibition was dependent on the continued presence of DA and could be mimicked by bromocriptine and stereospecifically prevented by the active but not the inactive isomer of the DA receptor antagonist butaclamol. Simultaneous administration of 10(-6) M DA with 10(-8) M TRH prevented the release of TSH and PRL. The effect of DA was transient, subsequent TRH responses being qualitatively and quantitatively normal.(ABSTRACT TRUNCATED AT 250 WORDS)
D000818:Animals; D002197:Capillary Action; D003584:Cytological Techniques; D004298:Dopamine / Q000494:pharmacology*; D008297:Male; D010477:Perfusion; D010903:Pituitary Gland, Anterior / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D011188:Potassium / Q000494:pharmacology; D011388:Prolactin / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013972:Thyrotropin / Q000378:metabolism*; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology*
D013973:Thyrotropin-Releasing Hormone; D011388:Prolactin; D013972:Thyrotropin; D011188:Potassium; D004298:Dopamine