Similarity of 5-HT2 receptor sites in dominant and subordinate vervet monkeys

Pharmacological studies using serotonergic agents have revealed status-linked behavioral effects in dominant and subordinate vervet monkeys. A possible explanation for the greater drug response observed in dominant animals is that there is a CNS difference between dominant and subordinate animals. Such differences could exist at the level of serotonin receptor sites, membrane responsiveness, or interaction with other neurotransmitters. We have examined the specific 3H-ketanserin binding in various regions of vervet monkey brain to evaluate the hypothesis that dominant and subordinate vervet monkeys differ in CNS 5-HT2 receptor sites. No differences were found in the number or affinity of 3H-ketanserin binding sites between dominant and subordinate animals. Further, no differences were found in the displacement of 3H-ketanserin binding by the serotonin agonist quipazine. These results suggest the conclusion that differences at 5-HT2 binding sites do not account for status-linked differences in behavioral drug response in vervet monkeys and that other or additional mechanisms must underlie status-related drug response differences.