Document Detail


The effect of blockade of dopamine receptors on the inhibition of episodic luteinizing hormone release during electrical stimulation of the arcuate nucleus in ovariectomized rats.
MedLine Citation:
PMID:  744005     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
This study examined the possible involvement of dopamine (DA) in mediating the inhibition of episodic LH release that occurs during electrical stimulation of the arcuate nucleus (ARH) in ovariectomized rats. Animals were treated before stimulation with pimozide (1.26--2.0 mg/kg) or d-butaclamol (1 mg/kg), blockers of DA receptors, or l-butaclamol. Apomorphine, which inhibits episodic LH release by activating DA receptors, was given near the end of the experiment to determine if these receptors were blocked. ARH stimulation suppressed pulsatile LH release in six rats when DA receptors were not blocked by pimozide (as well as two in which blockade was not tested). A transient increase occurred in one other animal. When DA receptors were blocked by pimozide, stimulation of the ARH inhibited episodic LH release in nine rats, suggesting that DA may have no role in mediating this inhibition. However, because increased LH release occurred in five additional animals, as well as in one with partial receptor blockade, the possibility remains that DA may perhaps have a minor role in this inhibitory response. Although ARH stimulation increased LH release after DA receptor blockade by d-butaclamol, this effect could not be ascribed to the DA antagonist property of this agent, because elevated blood LH levels also occurred during stimulation in rats treated with l-butaclamol, in which DA receptors were not blocked. d- and l-butaclamol may possess a non-stereospecific action on a non-dopaminergic event, thus reversing the response to ARH stimulation. Finally, whether DA receptors were blocked or not by pimozide, d-, or l-butaclamol, activation of the ventromedial hypothalamic and periventricular nucleus regions suppressed episodic LH release, but did not increase LH secretion. This suggests that the region through which stimulation can inhibit, but not increase, LH release may extend in the hypothalamus to these two areas.
Authors:
R V Gallo
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Endocrinology     Volume:  102     ISSN:  0013-7227     ISO Abbreviation:  Endocrinology     Publication Date:  1978 Apr 
Date Detail:
Created Date:  1979-05-23     Completed Date:  1979-05-23     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0375040     Medline TA:  Endocrinology     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1026-35     Citation Subset:  AIM; IM    
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MeSH Terms
Descriptor/Qualifier:
Animals
Butaclamol / pharmacology
Castration
Dopamine / physiology
Electric Stimulation
Female
Hypothalamus / physiology*
Luteinizing Hormone / secretion*
Pimozide / pharmacology
Rats
Receptors, Dopamine / drug effects*,  physiology
Chemical
Reg. No./Substance:
0/Receptors, Dopamine; 2062-78-4/Pimozide; 36504-93-5/Butaclamol; 9002-67-9/Luteinizing Hormone

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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