An examination of the behavioural specificity of hypophagia induced by 5-HT1B, 5-HT1C and 5-HT2 receptor agonists using the post-prandial satiety sequence in rats.
Previous studies have shown that administration of 5-HT1B, 5-HT1C or 5-HT2 agonists decreases food intake in rats. However, it has not been established whether these drugs induce satiety or decrease feeding by a non-specific mechanism. In the present study the post-prandial satiety sequence was used to characterise the actions of the 5-HT2 receptor agonist, 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI), the 5-HT1B/5-HT1C receptor agonists, 1-(3-chorophenyl) piperazine (mCPP) and 1-[3-(trifluoromethyl)phenyl] piperazine (TFMPP), and the 5-HT1B agonist, 5-methoxy-3-(1,2,3,6-tetrahydro-4-pyridinyl)H-indole (RU 24969), on feeding in rats. All four compounds reduced food intake in rats that had been food deprived overnight. The 5-HT1B/5-HT1C agonists, TFMPP (at a dose of 1.0 mg/kg) and mCPP (at a dose of 3.0 mg/kg), appeared to produce satiety as their effects on the satiety sequence were similar to those induced by a food pre-load. In contrast, the 5-HT1B agonist RU 24969 and the 5-HT2 agonist DOI did not produce behavioural profiles that resembled satiety. Thus, RU 24969 elevated active behaviours and did not accelerate resting whereas DOI appeared to induce hypophagia by a non-specific fragmentation of behaviour. The results suggest that simultaneous activation of 5-HT1B and 5-HT1C receptors may be sufficient to elicit behaviourally specific satiety in the rat. In contrast, selective activation of 5-HT2 receptors does not induce satiety but elicits active behaviours and decreases feeding by response competition.
Kitchener
S J
SJ
Merck Sharp & Dohme Research Laboratories, Neuroscience Research Centre, Harlow, Essex, UK.
Dourish
C T
CT
D000662:Amphetamines / Q000494:pharmacology; D000818:Animals; D004435:Eating / Q000187:drug effects; D005247:Feeding Behavior / Q000187:drug effects*; D006120:Grooming / Q000187:drug effects; D007211:Indoles / Q000494:pharmacology; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D010879:Piperazines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012528:Satiety Response / Q000187:drug effects*; D017366:Serotonin Receptor Agonists / Q000494:pharmacology*
D000662:Amphetamines; D007211:Indoles; D010879:Piperazines; D017366:Serotonin Receptor Agonists; C018406:1-(3-trifluoromethylphenyl)piperazine; C025145:5-methoxy 3-(1,2,3,6-tetrahydro-4-pyridinyl)1H indole; C015952:4-iodo-2,5-dimethoxyphenylisopropylamine; C015068:1-(3-chlorophenyl)piperazine