Stimulus deprivation increases pineal Gs alpha and G beta.
Denervation and other forms of stimulus deprivation cause an increase in the magnitude of subsequent responses, a phenomenon commonly referred to as denervation supersensitivity. This has been well demonstrated with the cyclic AMP response to norepinephrine in the pineal gland. In the present report, we address the question of whether stimulus deprivation alters alpha and beta subunits of the GTP binding regulatory protein that stimulates adenylyl cyclase activity (Gs). Stimulus deprivation of the pineal gland was produced by denervation (superior cervical ganglionectomy), decentralization of the superior cervical ganglia, or by exposure of the animal to continuous lighting. All increased both the alpha and beta subunits of Gs (Gs alpha and G beta) by up to fourfold, as estimated using semiquantitative western blot technology. These effects were detectable after 1 day of stimulus deprivation and were sustained for 2 weeks. The stimulatory effects of constant light-induced stimulus deprivation were also apparent by measuring cholera toxin-dependent ADP-ribosylation of Gs alpha, which revealed a four-fold increase in the amount of labeled substrate. The results of in vivo studies were confirmed with in vitro studies, which demonstrated a spontaneous increase in both Gs alpha and G beta during 72 h of organ culture. The constant light-induced increases in both Gs alpha and G beta were prevented by continuous administration of isoproterenol (0.3 mg/kg/day), supporting the suggestion that adrenergic stimulation controls the levels of Gs alpha and G beta. These studies indicate that stimulus deprivation increases both Gs alpha and G beta.(ABSTRACT TRUNCATED AT 250 WORDS)
Babila
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Section on Neuroendocrinology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892.
Klein
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DC
D000246:Adenosine Diphosphate Ribose / Q000378:metabolism; D000818:Animals; D002772:Cholera Toxin / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D005728:Ganglia, Sympathetic / Q000502:physiology*; D015171:Ganglionectomy; D007545:Isoproterenol / Q000494:pharmacology; D008027:Light; D008297:Male; D009924:Organ Culture Techniques; D010870:Pineal Gland / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley
D000246:Adenosine Diphosphate Ribose; D002772:Cholera Toxin; D019204:GTP-Binding Proteins; D007545:Isoproterenol