Biomedical subjects

L Uphouse

Publications and source records attributed to L Uphouse.

At least 19 recordsLinked to original sources

PubMed2004

GABAA-5-HT1A receptor interaction in the mediobasal hypothalamus.

Both serotonin (5-HT) and gamma-aminobutyric acid (GABA) modulate female rat lordosis behavior and appear to interact in their control of the behavior. The current experiments were designed to investigate the interaction between these two neurotransmitters in sexually receptive female rats. Ovariectomized female rats, with bilateral cannulae directed toward the ventromedial nucleus of the hypothalamus (VMN), were hormonally primed with 10 microg estradiol benzoate and 500 microg progesterone. Sexual behavior was examined after intracranial infusion with 200 ng (+/-)-8-hydroxy 2-(di-n-propylamino)tetralin (8-OH-DPAT), 25 ng (5-aminomethyl-3-hydroxyisoxazole)hydrobromide (muscimol), 10 ng bicuculline or a combination of the drugs. As expected, 8-OH-DPAT reduced lordosis behavior and muscimol attenuated this inhibition in a bicuculline-sensitive manner. Muscimol alone also reduced lordosis behavior. These findings contrast with several reports that muscimol facilitates lordosis behavior of suboptimally hormonally primed female rats. The current outcome is discussed in terms of procedural differences between the present experiment and earlier studies. It is suggested that muscimol may enhance lordosis responding in suboptimally hormonally primed rats by activation of GABAA receptors located dorsal to the VMN. In contrast, activation of receptors located more ventrally within the mediobasal hypothalamus (MBH) may inhibit the behavior of rats that are already sexually receptive.

8-Hydroxy-2-(di-n-propylamino)tetralin↗

PubMed2004

Effect of estrogen on the lordosis-inhibiting action of ketanserin and SB 206553.

The effects of the 5-HT(2A/2C) receptor antagonist, ketanserin, and the 5-HT(2C) receptor antagonist, SB 206553, on lordosis behavior were investigated in ovariectomized rats hormonally primed with estradiol benzoate (EB) (0.5 or 25 microg) and progesterone (500 microg). Both ketanserin and SB 206553 inhibited lordosis behavior after infusion into the ventromedial nucleus of the hypothalamus (VMN), but ketanserin was slightly more effective than the 5-HT(2C) receptor antagonist. Either drug was more effective in rats primed with 0.5 microg EB than in rats hormonally primed with 25 microg EB. These findings support the suggestion that estrogen may enhance functioning of the 5-HT(2) receptor family and thereby protect against the 5-HT(2) receptor antagonists. These data are consistent with prior suggestions that estrogen modulates functioning of 5-HT(2) receptors within the VMN and that 5-HT(2) receptors play a facilitatory role in the modulation of female rat lordosis behavior.

Analysis of Variance↗

PubMed2000

Factors elevating cAMP attenuate the effects of 8-OH-DPAT on lordosis behavior.

The effects of a soluble derivative of forskolin and of two membrane-permeable analogs of cAMP, dibutyryl cAMP, and 8-bromo-cAMP, on the ability of a serotonin (5-HT)(1A) receptor agonist to inhibit lordosis behavior were examined. Sexually receptive, proestrous rats received a bilateral infusion into the ventromedial nucleus of the hypothalamus (VMN) with 68 ng of the forskolin derivative 1, 1.5, 2, or 2.5 h prior to infusion with 200 ng of the 5-HT(1A) receptor agonist, (+/-)-8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT). Proestrous rats and ovariectomized rats, hormonally primed with 25 microg estradiol benzoate and 500 microg progesterone, were coinfused with 200 ng 8-OH-DPAT and either 50 microg dibutyryl cAMP or 5 microg 8-bromo-cAMP. In proestrous rats, prior infusion with the forskolin derivative reduced the effects of the 5-HT(1A) receptor agonist on lordosis behavior. The best protection occurred at 2 h; by 2.5 h after the preinfusion, any protective effect had disappeared. Coinfusion with either dibutyryl-cAMP or 8-bromo-cAMP reduced the effects of 8-OH-DPAT in proestrous rats. In hormone-primed, ovariectomized rats, dibutyryl cAMP offered significant protection against the effects of 8-OH-DPAT, but there was no protection with 8-bromo-cAMP. These findings are consistent with the speculation that 8-OH-DPAT's inhibition of lordosis behavior results, in part, from an inhibition of adenylyl cyclase, resulting from agonist activation of 5-HT(1A) receptors in the VMN. The findings are also consistent with our earlier observations for differences between proestrous rats and hormone-primed, ovariectomized rats in their response to 5-HT receptor-active compounds.

8-Bromo Cyclic Adenosine Monophosphate↗

PubMed2000

Female gonadal hormones, serotonin, and sexual receptivity.

The inhibitory and facilitatory effect of serotonergic (5-HT) receptor agonists and antagonists on the female rat lordosis reflex is reviewed. Emphasis is placed on the role of 5-HT(1A) and 5-HT(2) receptors. The effect of estrogen and progesterone on the lordosis response to 5-HT receptor-selective compounds is reviewed and potential mechanisms for hormonal modulation of the 5-HT system are suggested. Evidence that 5-HT modifies the female's position relative to a threshold for lordosis is presented. Finally, it is hypothesized that 5-HT's dual regulation of lordosis contributes to the female's ability to regulate mating behavior so that it occurs under physiological and environmental conditions that are conducive for individual, as well as species, survival.

Animals↗

PubMed1999

Estrous cycle modulation of extracellular serotonin in mediobasal hypothalamus: role of the serotonin transporter and terminal autoreceptors.

In vivo microdialysis was used to examine extracellular serotonin (5-HT) in the mediobasal hypothalamus (MBH) of male and female Fischer (CDF-344) rats. Females from the stages of diestrus, proestrus, and estrus were used. Additionally, ovariectomized rats, primed subcutaneously (s.c.) with estradiol benzoate or estradiol benzoate plus progesterone were examined. Extracellular 5-HT in the MBH varied with stage of the estrous cycle and with the light/dark cycle. Proestrous females had the highest microdialysate concentrations of 5-HT during the light portion of the light/dark cycle and lowest concentrations during the dark portion of the cycle. Diestrous females had the highest levels during the dark portion of the cycle, while males and estrous females showed little change between light and dark portions of the cycle. In ovariectomized rats, there was no effect of 2.5 microg or 25 microg estradiol benzoate (s.c.) on extracellular 5-HT; but the addition of 500 microg progesterone, 48 h after estrogen priming, reduced microdialysate 5-HT near the threshold for detection. In intact females and in males, reverse perfusion with 3 microM fluoxetine, a selective serotonin reuptake inhibitor (SSRI), or 2 microM methiothepin, a 5-HT receptor antagonist, increased microdialysate concentrations of 5-HT. Estrous females and males showed nearly a 4-fold increase in microdialysate 5-HT in response to fluoxetine while smaller responses were seen in diestrous and proestrous rats. In contrast, proestrous rats showed the largest response to methiothepin. Estrous females showed a delayed response to methiothepin, but there was no methiothepin-induced increase in extracellular 5-HT in males. These findings are discussed in reference to the suggestion that extracellular 5-HT in the MBH is regulated in a manner that is gender and estrous cycle dependent. The 5-HT terminal autoreceptor may exert a greater role in proestrous females; the serotonin transporter appears to play a more active role in the regulation of extracellular 5-HT in estrous females and in males.

Animals↗

PubMed1999

5-HT2C receptor involvement in female rat lordosis behavior.

Adult, hormone-primed, ovariectomized rats (CDF-344) with bilateral implants within the ventromedial nucleus of the hypothalamus (VMN), were injected with 0.5 microgram estradiol benzoate followed 48 h later with 500 microgram progesterone. This priming produced rats with 2 different levels of sexual receptivity. Rats with a lordosis to mount ratio (L/M)>/=0.5 were used to examine the potential lordosis-inhibiting effects of the 5-HT2A receptor antagonist, R(+)-a-(2, 3-dimethoxyphenyl)-1-[2(4-fluoro-phenylethyl)]-4-piperidine-methanol (MDL 100,907), and the 5-HT2C receptor antagonist, 5-methyl-1-(3-pyridylcarbamoyl)-1,2,3,5-tetrahydropyrrolo[2, 3-f]indole (SB 206553). Rats with low sexual receptivity (L/M<0.5) were bilaterally infused with the 5-HT2A/2C receptor agonist, (+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane HCl (DOI), or DOI plus either MDL 100,907 or SB 206553 to determine if either drug would attenuate the lordosis-facilitating effects of DOI. The 5-HT2C receptor antagonist, but not the 5-HT2A receptor antagonist, effectively inhibited lordosis behavior. Similarly, SB 206553 was more effective than MDL 100,907 in reducing the DOI-induced increase in lordosis responding. However, both drugs limited the duration of lordosis responding initiated by DOI. These results are consistent with prior suggestions that 5-HT2A/2C receptors within the VMN are involved in the modulation of lordosis behavior and lead to the suggestion that 5-HT2C, rather than 5-HT2A, receptors are primarily responsible for the effects of 5-HT2 receptor-active drugs on lordosis behavior.

Animals↗

PubMed1999

Reduced efficacy of 8-OH-DPAT's inhibition of lordosis behavior by prior estrogen treatment.

The effects of bilateral VMN infusion with the 5-HT1A receptor agonist, (+/-)-8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT; 200, 1000, or 2000 ng), on lordosis behavior were examined in hormonally primed ovariectomized rats. When rats were given a single injection with 25 microg estradiol benzoate followed 48 h later with 500 microg progesterone, inhibition of lordosis behavior was evident at all doses of 8-OH-DPAT. However, when rats were treated with 25 microg estradiol benzoate followed 7 days later with a second injection of 25 microg estradiol benzoate and then progesterone, none of the doses of 8-OH-DPAT effectively inhibited lordosis behavior. In some rats, cannulae were located near the most rostral portion of the VMN. In these rats, there was no effect of the second estrogen treatment on the response to 8-OH-DPAT. Therefore, a second experiment was performed to specifically evaluate the effects of two estradiol benzoate treatments on the response to bilateral 8-OH-DPAT infusion in the rostral VMN. In contrast to the reduced effectiveness of the 8-OH-DPAT infusion in the mid to caudal VMN in rats given two injections with estradiol benzoate, 2000 ng 8-OH-DPAT continued to effectively inhibit lordosis behavior following the 5-HT1A receptor agonist's infusion into the more rostral areas. These findings are discussed in relation to earlier studies in which the potency, but not the efficacy, of 8-OH-DPAT was reduced following systemic treatment with the 5-HT1A receptor agonist.

8-Hydroxy-2-(di-n-propylamino)tetralin↗

PubMed1998

Attenuation of the lordosis-inhibiting effects of 8-OH-DPAT by TFMPP and quipazine.

Regularly cycling, proestrous female rats received infusions of 200 ng of the serotonin (5-HT) 1A receptor agonist, (+/-) 8-hydroxy 2-(di-n-propylamino) tetralin-HBr (8-OH-DPAT), or 200 ng 8-OH-DPAT and 1000 or 2000 ng of N-(3-trifluoro-methylphenyl) piperazine hydrochloride (TFMPP) or 2-(1-piperazinyl) quinoline dimaleate (quipazine). Infusions were made bilaterally into the ventromedial nucleus of the hypothalamus (VMN). Animals receiving 200 ng 8-OH-DPAT exhibited a decline in lordosis behavior following infusion. Rats receiving 8-OH-DPAT and 1000 or 2000 ng quipazine or TFMPP were protected from the lordosis-inhibiting effects of 8-OH-DPAT, alone. Although both quipazine and TFMPP act on multiple 5-HT receptors, they overlap in their agonist action at 5-HT2 receptors. Consequently, these results provide further evidence supporting the contention that within the VMN, both 5-HT1A and 5-HT2 receptor subtypes contribute to the modulation of lordosis behavior in the female rat. The data are discussed in terms of the relative potency of 5-HT at 5-HT receptors mediating inhibition and facilitation of lordosis behavior.

8-Hydroxy-2-(di-n-propylamino)tetralin↗

PubMed1998

Functional integration among 5-hydroxytryptamine receptor families in the control of female rat sexual behavior.

Serotonin (5-HT) receptor interaction in the control of female rat lordosis behavior was examined. Ovariectomized rats, with bilateral implants in the ventromedial nucleus of the hypothalamus (VMN), were hormonally primed with 25 micrograms estradiol benzoate and 500 micrograms progesterone. Rats were infused with the 5-HT3 receptor antagonist, 3-tropanyl-indole-3 carbonylate (tropisetron; 500 ng), or were coinfused with the 5-HT3 receptor antagonist and the 5-HT2A/2C receptor agonist, 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI; 500, 1500, or 2000 ng). Additional ovariectomized, hormone-primed rats received bilateral VMN infusions with the 5-HT1A receptor agonist, 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT; 200 ng), or were coinfused with the 5-HT1A receptor agonist and the 5-HT3 receptor agonist, m-chlorophenyl-biguanide (mCPBG; 250, 500, or 1000 ng). Lordosis behavior was observed prior to VMN infusion, during the infusion and for 30 consecutive minutes thereafter. Tropisetron reduced the lordosis to mount (L/M) ratio in every animal investigated but the decline was attenuated by coinfusion with DOI. Similarly, the L/M ratio declined following infusion with 8-OH-DPAT and the decline was dose-dependently reduced by coinfusion with mCPBG. Only the 5-HT3 receptor agonist altered the quality of the lordosis reflex. These studies provide evidence that the effects of 5-HT on female rat lordosis behavior involve the integrated activity of at least 3 different 5-HT receptor families.

8-Hydroxy-2-(di-n-propylamino)tetralin↗

PubMed1998

Dose-dependent effects of estradiol benzoate on 5-HT1A receptor agonist action.

The lordosis-inhibiting effects of the 5-HT1A receptor agonist, (+/-)8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT), were examined in ovariectomized rats, hormone primed with 2.5, 7.5, or 25 micrograms estradiol benzoate plus 500 micrograms progesterone. 8-OH-DPAT (50, 100 or 200 ng per bilateral site) infused into the ventromedial nucleus of the hypothalamus (VMN), inhibited lordosis behavior in all hormone-treated conditions. However, animals primed with 2.5 micrograms estradiol benzoate were significantly more affected by the infusion than rats primed with 7.5 or 25 micrograms of the hormone. These findings strengthen prior speculations that 5-HT1A receptor function is modulated by estrogen.

8-Hydroxy-2-(di-n-propylamino)tetralin↗

PubMed1998

Facilitation of female rat lordosis behavior by hypothalamic infusion of 5-HT(2A/2C) receptor agonists.

Ovariectomized rats were hormonally primed with 0.5 microg estradiol benzoate and 500 microg progesterone to produce two groups of rats differing in their lordosis behavior. Females with a lordosis to mount (L/M) ratio < 0.5 were used to test the hypothesis that 5-HT(2A/2C) receptor agonists could facilitate lordosis behavior. Females with L/M ratios > or = 0.5 were used to evaluate the potential suppressive effect of 5-HT(2A/2C) receptor compounds. Lordosis behavior was examined following bilateral infusion of drugs into the ventromedial nucleus of the hypothalamus (VMN). Drugs examined were the 5-HT(2A/2C) receptor agonist, (+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane HCl (DOI), the 5-HT(2A/2C) receptor antagonist, 3-[2-[4-(4-fluorobenzoyl)-1-piperdinyl]ethyl]-2,4(1H,3H)-quinazoli nedione tartrate (ketanserin tartrate), and the non-selective 5-HT receptor agents, 2-(1-piperazinyl)quinoline dimaleate (quipazine) and N-(3-trifluoromethylphenyl)piperazine HCl (TFMPP). Drugs with agonist action at 5-HT(2A/2C) receptors increased lordosis behavior in rats with low sexual receptivity. The 5-HT(2A/2C) receptor antagonist, ketanserin, inhibited lordosis behavior in sexually receptive rats. DOI attenuated the lordosis-inhibiting effect of ketanserin, but ketanserin was less effective in preventing DOI from increasing lordosis behavior. These results strengthen prior inferences that activation of 5-HT(2A/2C) receptors can facilitate lordosis behavior and that the VMN is one site at which such facilitation can occur.

Amphetamines↗

PubMed1997

5-HT3 receptors in the ventromedial nucleus of the hypothalamus and female sexual behavior.

Within the ventromedial nucleus of the hypothalamus (VMN), serotonin exerts a dual role in the control of female rat lordosis behavior. Most emphasis has been placed on 5-HT1A and 5-HT2 receptors, which inhibit and facilitate the behavior, respectively. In the current experiment, a potential role for VMN 5-HT3 receptors in the control of lordosis behavior was examined. Ovariectomized rats, hormonally primed with 25 microg estradiol benzoate and 500 microg progesterone, received bilateral VMN infusions with 100 ng, 250 ng or 500 ng of the 5-HT3 receptor antagonist, tropisetron. In these rats, there was a dose-dependent decline in both the lordosis to mount (L/M) ratio and in the quality of the lordosis reflex with 500 ng tropisetron producing the most consistent change in lordosis behavior. Relative to hormone-primed, ovariectomized rats, lordosis behavior of proestrous females was less affected by VMN infusions with the 5-HT3 receptor antagonist. The 5-HT3 receptor agonist, m-chlorophenylbiguanide (mCPBG), attenuated the effect of tropisetron; of the three mCPBG doses (500 ng, 1000 ng, 1500 ng) examined, 1000 ng was the most effective, perhaps because, alone, 1500 ng mCPBG slightly reduced lordosis behavior. These observations emphasize the potential role for VMN 5-HT3 receptors in the control of lordosis behavior.

Animals↗

PubMed1997

Modulation of the behavioral effects of 8-OH-DPAT by estrogen and DOI.

The effects of female gonadal hormones on 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT)-induced flat body posture, hypothermia, and eating behavior were examined. Ovariectomized rats were injected with estradiol benzoate, estradiol benzoate, and progesterone, progesterone or vehicle on each of 2 consecutive weeks. On each week, the behavioral effects of the 5-HT1A receptor agonist, 8-OH-DPAT, or the combination of both 8-OH-DPAT and 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane hydrochloride (DOI), a 5-HT2 receptor agonist, were examined. 8-OH-DPAT produced flat body posture, hypothermia, and eating behavior on each week of the experiment. Female gonadal hormones modulated eating behavior (e.g., rats treated with estradiol benzoate showed less eating after 8-OH-DPAT), but had no effect on either flat body posture or hypothermia. The 5-HT2 receptor agonist, DOI, attenuated 8-OH-DPAT's effect on flat body posture and on hypothermia, but not on eating behavior. 8-OH-DPAT's effect on all behaviors declined during the second week of the experiment.

8-Hydroxy-2-(di-n-propylamino)tetralin↗

PubMed1997

Multiple serotonin receptors: too many, not enough, or just the right number?

In this manuscript, current knowledge about central nervous system serotonin (5-HT) receptors is discussed with an emphasis toward describing the functional significance of the multiple 5-HT receptors. Five characteristics of 5-HT receptors, which are hypothesized to contribute to this functional significance, are discussed: (a) 5-HT has varying affinity and potency for the different receptor subtypes; (b) multiple transduction pathways are used by the different receptor subtypes; (c) receptor subtypes differ in their susceptibility to agonist-mediated desensitization/downregulation; (d) receptor subtypes interact in mediating cellular responses to the neurotransmitter; and (e) receptor subtypes respond differently to changes in the physiological environment. It is hypothesized that these characteristics of the multiple neurotransmitter receptors provide the nervous system with a capacity for coding and decoding of 5-HT-mediated neuronal transmission that could not take place with a single neurotransmitter receptor. Serotonergic regulation of female reproduction and regulation of glucocorticoid release are used to illustrate the integrative potential deriving from the existence of multiple 5-HT receptors.

Animals↗

PubMed1996

Effects of mianserin and ketanserin on lordosis behavior after systemic treatment or infusion into the ventromedial nucleus of the hypothalamus.

The effects of the 5-HT2A/2C antagonists, mianserin and ketanserin, were investigated in proestrous rats and in ovariectomized rats hormonally primed with estradiol benzoate and progesterone. Drugs were administered systemically or by infusion into the vicinity of the ventromedial nucleus of the hypothalamus (VMN). By both routes of administration, inhibition of lordosis behavior was seen following treatment with the 5-HT2A/2C antagonists, but the magnitude of the decline was smaller in proestrous than in hormone-primed, ovariectomized rats. The results of these studies are discussed in terms of the dual role of serotonin in the control of female sexual behavior.

Animals↗

PubMed1996

Prior treatment with estrogen attenuates the effects of the 5-HT1A agonist, 8-OH-DPAT, on lordosis behavior.

The effects of repeated treatment with estradiol benzoate to ovariectomized rats on the lordosis-inhibiting action of the 5-HT1A agonist, 8-hydroxy-2(di-n-propylamino) tetralin (8-OH-DPAT), were examined. In the first week of hormonal priming, when rats were injected with estradiol benzoate (2.5-50 micrograms) plus 500 micrograms progesterone, all groups were inhibited by intraperitoneal (i.p.) treatment with 0.15 mg/kg 8-OH-DPAT. However, in the second week of hormone treatment, the effects of 8-OH-DPAT on lordosis behavior were dose-dependently attenuated by estradiol benzoate. Such attenuation was present when animals were treated with estradiol benzoate on the day of ovariectomy and when the first estradiol benzoate treatment was delayed for 2 weeks after ovariectomy. At least 3 days after the first injection with estradiol benzoate were required before the inhibitory effects of i.p. treatment with 8-OH-DPAT were attenuated. Although the magnitude was reduced, higher doses of 8-OH-DPAT (0.4, 0.45, and 0.5 mg/kg) continued to inhibit lordosis behavior even after the second hormonal priming. When 8-OH-DPAT was infused directly into the ventromedial nucleus of the hypothalamus (VMN), the lordosis-inhibiting effects of 8-OH-DPAT were reduced as soon as 2 days after the first estradiol benzoate injection. These data are interpreted as evidence that (1) estradiol benzoate's attenuation of the effects of 8-OH-DPAT on lordosis behavior is both dose and time dependent; (2) 5-HT1A receptor action in the VMN is attenuated by the hormone treatment; and (3) female gonadal hormones reduce the potency of the 5-HT1A agonist, 8-OH-DPAT, in inhibiting lordosis behavior.

8-Hydroxy-2-(di-n-propylamino)tetralin↗

PubMed1996

Protective actions of the 5-HT2A/2C receptor agonist, DOI, on 5-HT1A receptor-mediated inhibition of lordosis behavior.

Sexually receptive proestrous rats were infused bilaterally into the ventromedial nucleus of the hypothalamus (VMN) with 200 ng of 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT), 1000 or 2000 ng of 5-methoxy-3-(di-n-propylamino) chroman (5-MEO-DPAC), or 1000 or 2000 ng of serotonin (5-HT) plus or minus the 5-HT2A/2C agonist, (2,5-dimethoxy-4-iodophenyl)-2-aminopropane HCl (DOI). DOI protected against the lordosis-inhibiting effects of 5-HT and each of the 5-HT1A agonists. These results substantiate a prior report that 2000 ng DOI could protect against the lordosis-inhibiting action of 200 ng 8-OH-DPAT and demonstrate that such protection is not unique to a single 5-HT1A agonist. Consequently, these results strengthen evidence that functionally significant interactions occur among 5-HT receptors within the VMN.

Amphetamines↗

PubMed1996

5-HT1A receptor antagonists and lordosis behavior.

In proestrous rats, serotonin 1A (5-HT1A) receptor agonists inhibit lordosis behavior within 5-15 min following infusion into the ventromedial nucleus of the hypothalamus (VMN). In the present report, the lordosis-inhibiting effects of the 5-HT1A agonist [(+/-) 8-hydroxy-2- (di-n-propylamino) tetralin) (8-OH-DPAT] were shown to be attenuated with 5-HT1A receptor antagonists. Two compounds, propranolol and pindolol, that function as both beta-adrenergic and 5-HT1A receptor antagonists, and (+) WAY100135 (chiral N-t-butyl-3-(1-(4-(2-methoxy) phenyl)piperazinyl)-1-phenylpropionamide dihydrochloride, quarter hydrate), a more selective 5-HT1A receptor antagonist, were found to reduce the lordosis-inhibiting effects of 8-OH-DPAT infusion into the VMN. Proestrous rats were co-infused into the VMN with 200 ng 8-OH-DPAT plus 1000 ng or 2000 ng pindolol, 1000 ng or 2000 ng propranolol, or 2000 ng (+) WAY100135. Co-infusion with 1000 ng or 2000 ng pindolol attenuated the inhibitory effects of 8-OH-DPAT; co-infusion of 1000 ng, but not 2000 ng, propranolol, reduced the effects of 8-OH-DPAT; and co-infusion with 2000 ng (+) WAY100135 attenuated the effects of 8-OH-DPAT. Bilateral VMN infusion with 2500 ng (+) WAY100135 facilitated lordosis behavior in suboptimally, hormone-primed ovariectomized rats. These findings strengthen the argument that the inhibitory effect of 5-HT1A receptor agonists on lordosis behavior is the result of their activation of VMN 5-HT1A receptors.

8-Hydroxy-2-(di-n-propylamino)tetralin↗