Effects of 5-HT1A receptor agonists and L-5-HTP in Montgomery's conflict test.
The effects of the pyrimidinyl-piperazines buspirone, gepirone, ipsapirone and their common metabolite 1-(2-pyrimidinyl)-piperazine (PmP) as well as of 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) and L-5-hydroxytryptophan (L-5-HTP) were investigated in Montgomery's conflict test--an animal anxiety model based on the animal's inborn urge to explore a new environment and its simultaneous fear of elevated, open spaces. Subcutaneous buspirone (32-128 nmol/kg), gepirone (32-128 nmol/kg), ipsapirone (32-512 nmol/kg) and 8-OH-DPAT (50-200 nmol/kg), as well as intraperitoneal L-5-HTP (56 mumol/kg) produced anxiolytic-like effects. However, at higher doses the magnitude of these effects decreased and overall the dose-response curves displayed inverted U-shapes. The highest doses (2048 nmol/kg) of buspirone and of gepirone even decreased responding below control levels, possibly in part due to concomitant sedation/motor impairment. After L-5-HTP (448 mumol/kg) and PmP (512 nmol/kg) anxiogenic-like effects were observed. The results indicate that anxiolytic- and anxiogenic-like effects of drugs affecting central serotonergic neurotransmission can be obtained in a sensitive rat anxiety model which neither involves consummatory behavior nor punishment. The anxiolytic-like effects of these compounds may be due to their 5-HT1A agonistic properties. Moreover, the present data may provide support for a possible reciprocal association of presynaptic 5-HT1A receptors vs. postsynaptic 5-HT1A as well as 5-HT2 receptors with regard to anxiety.
Söderpalm
B
B
Department of Pharmacology, University of Göteborg, Sweden.
Hjorth
S
S
Engel
J A
JA
D006916:5-Hydroxytryptophan / Q000494:pharmacology; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D000818:Animals; D014151:Anti-Anxiety Agents / Q000494:pharmacology*; D002065:Buspirone / Q000031:analogs & derivatives / Q000494:pharmacology*; D003220:Conflict, Psychological; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D011743:Pyrimidines / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D011985:Receptors, Serotonin / Q000187:drug effects; D013764:Tetrahydronaphthalenes / Q000494:pharmacology
D014151:Anti-Anxiety Agents; D011743:Pyrimidines; D011985:Receptors, Serotonin; D013764:Tetrahydronaphthalenes; C043077:ipsapirone; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D006916:5-Hydroxytryptophan; C037921:1-(2-pyrimidinyl)piperazine; C039979:gepirone; D002065:Buspirone