Effect of supersensitivity of pre- and postsynaptic dopamine receptors on the activity of endogenous inhibitor of cAMP dependent protein kinase in rat striatum.
Small presynaptically active doses of apomorphine (50-100 micrograms/kg) induced an increase, while large doses (1-10 mg/kg) provoked a decrease of type I inhibitor activity in rat striatum. Supersensitivity of postsynaptic D1 receptors was produced in rats by i.c.v. injection of 6-hydroxydopamine (6-OH-DA) and supersensitivity of presynaptic dopamine autoreceptors by i.p. administration of reserpine (1 mg/kg daily for 4 days). In reserpine pretreated rats apomorphine produced an increase in type I inhibitor activity after about 5 times lower doses than in control rats. This effect of apomorphine was blocked by aminophylline and by presynaptically active doses of haloperidol. In 6-OH-DA pretreated rats small doses of apomorphine did not change the type I inhibitor activity. The apomorphine induced decrease of type I inhibitor activity was seen after about 10 times lower doses of apomorphine than in control rats. This action of apomorphine was blocked by postsynaptically active doses of haloperidol and enhanced by aminophylline. The obtained results show that supersensitivity of presynaptic D2 dopamine autoreceptors and postsynaptic D1 receptors is accompanied by changes in the reactiveness of type I inhibitor activity to apomorphine.
D000628:Aminophylline / Q000494:pharmacology; D000818:Animals; D001058:Apomorphine / Q000494:pharmacology; D002352:Carrier Proteins / Q000378:metabolism*; D003342:Corpus Striatum / Q000201:enzymology*; D006220:Haloperidol / Q000494:pharmacology; D006892:Hydroxydopamines / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D016627:Oxidopamine; D047428:Protein Kinase Inhibitors; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000187:drug effects*; D017981:Receptors, Neurotransmitter / Q000187:drug effects*; D012110:Reserpine / Q000494:pharmacology
D002352:Carrier Proteins; D006892:Hydroxydopamines; D047908:Intracellular Signaling Peptides and Proteins; D047428:Protein Kinase Inhibitors; D011954:Receptors, Dopamine; D017981:Receptors, Neurotransmitter; C015482:protein kinase modulator; D000628:Aminophylline; D012110:Reserpine; D016627:Oxidopamine; D006220:Haloperidol; D001058:Apomorphine