Cookies on this website
We use cookies to ensure that we give you the best experience on our website. If you click 'Continue' we'll assume that you are happy to receive all cookies and you won't see this message again. Click 'Find out more' for information on how to change your cookie settings.

The somatodendritic 5-HT1A autoreceptor regulating 5-HT neuronal activity is currently poorly defined pharmacologically because there are no specific antagonists, but also because potent and stereoselective agonists are scarce. Moreover, there have been few, if any, attempts to specifically investigate structure-activity relationships for agonists acting at this site. Employing brain microdialysis techniques, we have examined the effects of the enantiomers of cis-8-hydroxy-1-methyl-2-(di-n-propylamino)tetralin (ALK-3; 0.01-0.3 mg/kg s.c.), its trans-1-methyl analogue (ALK-4; 0.3 mg/kg s.c.) and the pure enantiomers of the parent compound--8-OH-DPAT (0.3 mg/kg s.c.)--in an attempt to address stereochemical agonist structure-activity requirements of 5-HT release-controlling 5-HT1A autoreceptors in brain. The cis-1-methylated 8-OH-DPAT analogue (+)ALK-3 was comparable to the parent compound in reducing the 5-HT output from rat ventral hippocampus. In comparison, both (-)ALK-3 and the racemic trans-diastereomer to ALK-3, ALK-4, were inactive, while the two stereoisomers of 8-OH-DPAT strongly reduced 5-HT release. Pretreatment with (-)pindolol (8 mg/kg s.c.), which has high affinity for 5-HT1A radioligand binding sites, blocked the reduction of hippocampal 5-HT release induced by a submaximally effective dose of (+)ALK-3. The direct intrahippocampal administration of (+)ALK-3 (10 microM) via the perfusion medium did not affect 5-HT output. In summary, the data indicate that (+)ALK-3, like 8-OH-DPAT, is a very potent 5-HT receptor agonist which inhibits terminal 5-HT release in rat hippocampus, probably via activation of somatodendritic 5-HT1A autoreceptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Type

Journal article

Journal

Naunyn Schmiedebergs Arch Pharmacol

Publication Date

03/1990

Volume

341

Pages

149 - 157

Keywords

3,4-Dihydroxyphenylacetic Acid, 8-Hydroxy-2-(di-n-propylamino)tetralin, Animals, Brain Chemistry, Dialysis, Hippocampus, Hydroxyindoleacetic Acid, Male, Naphthalenes, Pindolol, Rats, Rats, Inbred Strains, Receptors, Serotonin, Serotonin, Stereoisomerism, Tetrahydronaphthalenes