Temperature-dependent 5-hydroxytryptamine (5-HT)-sensitive [3H]spiperone binding to rat cortical membranes: regulation by guanine nucleotide and antidepressant treatment.
5-Hydroxytryptamine (5-HT)-sensitive binding of [3H]spiperone to rat cortical membranes was examined at 22 degrees C and 37 degrees C. At the lower temperature a significantly higher density of specific sites with identical affinity for [3H]spiperone (0.15 nM) was observed. Furthermore, a proportion of sites at 22 degrees C, although not at 37 degrees C, possessed high affinity for 5-HT and these were apparently converted to low affinity sites by GTP (100 microM). Examination of the apparent affinities of the 5-HT derivatives 5-methoxytryptamine, 5,6-dihydroxytryptamine and tryptamine revealed differences in the potencies of these analogs that were particularly evident for the high affinity proportion of sites observed at 22 degrees C. Subchronic treatment of rats with the antidepressants mianserin and iprindole reduced the density of [3H] spiperone binding sites when assays were performed at either temperature. However, antidepressant treatment appeared to preferentially reduce the number of sites that possess high affinity for 5-HT.
D000818:Animals; D001665:Binding Sites; D002090:Butyrophenones / Q000378:metabolism*; D002540:Cerebral Cortex / Q000187:drug effects* / Q000378:metabolism; D003984:Dibenzazepines / Q000494:pharmacology*; D006150:Guanine Nucleotides / Q000502:physiology*; D007211:Indoles / Q000494:pharmacology*; D007488:Iprindole / Q000494:pharmacology*; D008297:Male; D008803:Mianserin / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D011985:Receptors, Serotonin / Q000378:metabolism; D012701:Serotonin / Q000378:metabolism / Q000502:physiology*; D013134:Spiperone / Q000378:metabolism*; D013696:Temperature
D002090:Butyrophenones; D003984:Dibenzazepines; D006150:Guanine Nucleotides; D007211:Indoles; D011985:Receptors, Serotonin; D008803:Mianserin; D012701:Serotonin; D013134:Spiperone; D007488:Iprindole