Pulsatile growth hormone and prolactin: effects of (+) butaclamol, a dopamine receptor blocking agent.
Growth hormone (rGH) and prolactin (rPRL) secretory profiles were obtained before and after treatment with a dopamine receptor blocking agent, (+) butaclamol, in 10 male rats chronically implanted with right atrial cannulae. Mean rGH plasma concentrations, determined by planimetry, were reduced (202 +/- 20 ng/ml vs. 135 +/- 20ng/ml, P less than .01), but the basic configuration and periodicity of rGH secretory bursts were unaltered. Mean rPRL plasma concentrations were elevated (11.1 +/- 2.1 ng/ml vs 65.5 +/- 8.1 ng/ml, P less than .0005), but rPRL episodic secretion was still apparent. It is concluded that dopaminergic neurons have a minor role in facilitating episodic rGH secretion. Furthermore, persisting episodic rPRL secretion in rats administered a dopamine antagonist suggests that rPRL feedback inhibition does not inactivitate the neural mechanism generating episodic rPRL secretion.
D000818:Animals; D002069:Butaclamol / Q000494:pharmacology*; D003986:Dibenzocycloheptenes / Q000494:pharmacology*; D013006:Growth Hormone / Q000097:blood*; D008297:Male; D011388:Prolactin / Q000097:blood*; D051381:Rats; D011954:Receptors, Dopamine / Q000378:metabolism; D013997:Time Factors
D003986:Dibenzocycloheptenes; D011954:Receptors, Dopamine; D011388:Prolactin; D013006:Growth Hormone; D002069:Butaclamol