Hypothalamic infusion of the 5-HT2/1C agonist, DOI, prevents the inhibitory actions of the 5-HT1A agonist, 8-OH-DPAT, on lordosis behavior.
Sexually receptive, intact, proestrous rats were infused bilaterally into the ventromedial nucleus of the hypothalamus (VMN) with 200 ng of the 5-HT1A agonist, 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), with 2000 ng of the 5-HT2/1C agonist, (+/-)-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane HCl (DOI), or with both 8-OH-DPAT and DOI. Alone, VMN infusions of 8-OH-DPAT, but not DOI, inhibited lordosis behavior. When 2000 ng DOI was infused simultaneously with 8-OH-DPAT, the inhibitory effects of 8-OH-DPAT were completely abolished. These results suggest that neural sites responsible for the reported facilitatory effects of 5-HT2/1C agonists on lordosis behavior coexist in the VMN with those sites in which 5-HT1A agonists are effective in reducing lordosis behavior. In contrast to the protective action of the 5-HT2/1C receptor agonist following VMN infusion, no protection was seen when both DOI and 8-OH-DPAT were administered intraperitoneally. Thus, the interaction of these two receptor subtypes in the control of lordosis behavior may be different in regions outside the VMN.
Uphouse
L
L
Department of Biology, Texas Woman's University, Denton 76204.
Andrade
M
M
Caldarola-Pastuszka
M
M
Maswood
S
S
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000008:administration & dosage / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D000662:Amphetamines / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D005260:Female; D007267:Injections; D007274:Injections, Intraperitoneal; D011187:Posture / Q000502:physiology*; D011359:Proestrus / Q000502:physiology; D051381:Rats; D011916:Rats, Inbred F344; D017366:Serotonin Receptor Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D012726:Sexual Behavior, Animal / Q000187:drug effects*; D014697:Ventromedial Hypothalamic Nucleus / Q000033:anatomy & histology / Q000502:physiology*
D000662:Amphetamines; D017366:Serotonin Receptor Agonists; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; C015952:4-iodo-2,5-dimethoxyphenylisopropylamine