5-HT1C receptor antagonists have anxiolytic-like actions in the rat social interaction model.
The effects of a range of 5-HT receptor antagonists were examined in an animal model of anxiety--the social interaction test. Six antagonists with high affinity for 5-HT1C receptors; mianserin, (+) mianserin, 1-naphthyl piperazine, ICI 169 369, pizotifen and LY 53857 all increased the time spent in active social interaction by pairs of weight-matched rats under high light unfamiliar conditions. As locomotion was only increased by 1-NP and then only at high doses, the effect of the drugs is consistent with anxiolysis. These properties were shared by the benzodiazepine anxiolytic chlordiazepoxide but not by the specific 5-HT2 antagonists ketanserin and altanserin, nor by the 5-HT1A and 5-HT1B antagonists cyanopindolol and pindolol. Similarly, neither the adrenergic alpha 2 antagonist idazoxan, the alpha 2 antagonist and putative 5-HT1D partial agonist yohimbine nor the H1 antagonist mepyramine had any significant effect. Since (+)mianserin, LY 53857 and ICI 169 369 at least have low affinity for 5-HT3 receptors these receptors are also unlikely to be involved. The results therefore imply that the observed anxiolytic effects of the drugs are likely to be mediated by 5-HT1C receptor blockade.
SmithKline Beecham Pharmaceuticals, Harlow, Essex, UK.
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Kennett
D000818:Animals; D014151:Anti-Anxiety Agents / Q000494:pharmacology*; D007398:Interpersonal Relations; D008297:Male; D008960:Models, Psychological; D009043:Motor Activity / Q000187:drug effects; D010879:Piperazines / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012702:Serotonin Antagonists
D014151:Anti-Anxiety Agents; D010879:Piperazines; D012702:Serotonin Antagonists; C015068:1-(3-chlorophenyl)piperazine