In vitro characterisation of dopamine receptors in the superior colliculus of the rat.
In membrane preparations of superior colliculus of the rat, the binding of [3H]spiperone (0.15 nM) was displaced by the incorporation of (+)-butaclamol, haloperidol, apomorphine and (+/-)-sulpiride, but not by (-)-butaclamol, prazosin, propranolol, ketanserin or cinanserin. The Ki values for the displacement of [3H]spiperone by (+/-)-sulpiride, (+)-butaclamol and haloperidol were similar in tissue preparations from superior colliculus and striatum. Equilibrium analysis of the specific binding of [3H]spiperone (0.03-1.0 nM), defined by 10(-5) M (+/-)-sulpiride, to membrane preparations of the superior colliculus, showed the interaction to be saturable and of high affinity. However, the Bmax was only approximately 10% of that found in preparations of striatum; the apparent dissociation constant (KD) was the same in both preparations of the superior colliculus and striatum. Uptake of [3H]dopamine into synaptosomal preparations of the superior colliculus was approximately 20% of that found in synaptosomes from the striatum. In preparations of striatum nomifensine, but not desipramine or fluoxetine, inhibited the uptake of [3H]dopamine. However, in preparations from the superior colliculus, nomifensine, desipramine and fluoxetine were without effect on the uptake of [3H]dopamine. Dopamine, 3,4-dihydroxyphenylacetic acid (DOPAC) and 3-methoxytyramine (3-MT) were present in small concentrations in the superior colliculus. Homovanillic acid (HVA) was present in larger concentrations and the HVA plus DOPAC/dopamine ratios were greater in the superior colliculus than in the striatum. The superior colliculus contained only small amounts of noradrenaline but 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) were present in larger amounts.(ABSTRACT TRUNCATED AT 250 WORDS)
D000818:Animals; D001058:Apomorphine / Q000378:metabolism; D001667:Binding, Competitive; D002069:Butaclamol / Q000378:metabolism; D002395:Catecholamines / Q000378:metabolism*; D003342:Corpus Striatum / Q000378:metabolism; D006220:Haloperidol / Q000378:metabolism; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000378:metabolism*; D012701:Serotonin / Q000378:metabolism; D013134:Spiperone / Q000378:metabolism*; D013469:Sulpiride / Q000378:metabolism; D013477:Superior Colliculi / Q000378:metabolism*; D013574:Synaptosomes / Q000378:metabolism
D002395:Catecholamines; D011954:Receptors, Dopamine; D012701:Serotonin; D013134:Spiperone; D013469:Sulpiride; D002069:Butaclamol; D006220:Haloperidol; D001058:Apomorphine