A. Wolf et al., FACILITATION OF FEMALE RAT LORDOSIS BEHAVIOR BY HYPOTHALAMIC INFUSIONOF 5-HT2A 2C RECEPTOR AGONISTS/, Brain research, 779(1-2), 1998, pp. 84-95
Ovariectomized rats were hormonally primed with 0.5 mu g estradiol ben
zoate and 500 mu g progesterone to produce two groups of rats differin
g in their lordosis behavior. Females with a lordosis to mount (L/M) r
atio < 0.5 were used to test the hypothesis that 5-HT2A/2C receptor ag
onists could facilitate lordosis behavior. Females with L/M ratios gre
ater than or equal to 0.5 were used to evaluate the potential suppress
ive effect of 5-HT2A/2C receptor compounds. Lordosis behavior was exam
ined following bilateral infusion of drugs into the ventromedial nucle
us of the hypothalamus (VMN). Drugs examined were the 5-HT2A/2C recept
or agonist, +/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane pane HC
l (DOI), the 5-HT2A/2C receptor antagonist, l)-1-piperdinyl]ethyl]-2,4
(1H,3H)-quinazolinedione tartrate (ketanserin tartrate), and the non-s
elective 5-HT receptor agents, 2-(1-piperazinyl)quinoline dimaleate (q
uipazine) and N-(3-trifluoromethylphenyl)piperazine HCl (TFMPP). Drugs
with agonist action at 5-HT2A/2C receptors increased lordosis behavio
r in rats with low sexual receptivity. The 5-HT2A/2C receptor antagoni
st, ketanserin, inhibited lordosis behavior in sexually receptive rats
. DOI attenuated the lordosis-inhibiting effect of ketanserin, but ket
anserin was less effective in preventing DOI from increasing lordosis
behavior. These results strengthen prior inferences that activation of
5-HT2A/2C receptors can facilitate lordosis behavior and that the VMN
is one site at which such facilitation can occur. (C) 1998 Elsevier S
cience B.V.