The 5-HT_1A Receptor Full Agonist, 8-OH-DPAT Inhibits ACTH-Induced 5-HT_2A Receptor Hyperfunction in Rats: Involvement of 5-HT_1A Receptors in the DOI-Induced Wet-Dog Shakes in ACTH-Treated Rats

Abstract

We examined the influence of 8-hydroxy-2-di-n-propylamino tetralin (8-OH-DPAT), a serotonin 1A (5-HT_1A) receptor full agonist, on the wet-dog shake response induced by the (±)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI), a 5-HT_2A receptor agonist, in adrenocorticotropic hormone (ACTH)-treated rats. Chronic ACTH (100 μg/rat, s.c.) treatment for 14 d increased the wet-dog shake response induced DOI. The 8-OH-DPAT inhibited the wet-dog shake response induced by DOI in rats with ACTH for 14 d. On the other hand, the 8-OH-DPAT-induced hypothermia and flat body posture were inhibited when ACTH was administered for 14 d. These findings suggest that chronic treatment with ACTH decreased the sensitivity of the 5-HT_1A receptor system; however, the inhibitory effects from the 5-HT_1A receptors to the 5-HT_2A receptor system is not inhibited in ACTH-treated rats.