Biomedical subjects

S D Mendelson

Publications and source records attributed to S D Mendelson.

28 records · Page 2Linked to original sources

PubMed1987

An improved chamber for the observation and analysis of the sexual behavior of the female rat.

A new chamber designed to evaluate the sexual behavior of rats was found to have distinct advantages over chambers typically described in the literature. The new testing chamber is narrow, which maintains a male and female rat in the optimal orientation for the observer to view sexual behavior, i.e., in the side view. Moreover, the chamber consists of an upper and lower level, which allows the females an avenue of escape from the male. In Experiment 1 it was shown that use of the chamber increased the reliability of data gathered in evaluating the lordosis behavior of female rats. In Experiment 2 it was shown that the new chamber could be used to evaluate the pacing of copulation by female rats.

Animals↗

PubMed1986

Effects of 5-HT1A selective anxiolytics on lordosis behavior: interactions with progesterone.

Ipsapirone and gepirone, but not buspirone, facilitated lordosis in estrogen-treated rats, whereas all three drugs inhibited this behavior in rats treated with estrogen and progesterone. When administered at higher doses, ipsapirone, gepirone and buspirone inhibited lordosis in rats treated with either estrogen or estrogen and progesterone. These data are consistent with the proposal that 5-HT1A receptors mediate lordosis-inhibiting effects of 5-HT, and further suggest that some 5-HT1A agonists may facilitate lordosis by activity at autoreceptors. Finally, these data show that progesterone may modulate activity at 5-HT1A receptors.

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

PubMed1986

Serotonin type 2 antagonists inhibit lordosis behavior in the female rat: reversal with quipazine.

The theory that activation of serotonin type 2 (5-HT2) receptors facilitates lordosis behavior in the female rat was tested. The 5-HT2 antagonists pizotefin, cyproheptadine, metitepine, and ketanserin were found to inhibit lordosis behavior in ovariectomized rats that had been primed with estradiol benzoate and progesterone. Pipamperone was ineffective. The 5-HT2 agonist quipazine was ineffective alone, but it reversed the inhibitory effects of pizotefin, cyproheptadine, and ketanserin. It did not reverse the effects of metitepine. The results support the theory of a facilitatory role for 5-HT2 receptors in lordosis behavior.

Analysis of Variance↗

PubMed1986

Methysergide inhibits and facilitates lordosis behavior in the female rat in a time-dependent manner.

Reports in the literature have indicated a facilitatory effect of the serotonin antagonist methysergide on lordosis behavior, suggesting an inhibitory role for serotonergic activity. In the present series of experiments, methysergide (7 mg/kg) was found to inhibit lordosis behavior 30 min after intraperitoneal administration to females, treated chronically with estradiol benzoate, or acutely with estradiol benzoate and progesterone. However, methysergide was found to facilitate lordosis behavior 200 and 300 min after administration to female rats treated acutely with estradiol benzoate. These data suggest a time-dependent inhibitory effect of methysergide, and are consistent with the hypothesis that the activity of serotonin type 2 receptors facilitates lordosis behavior in the female rat.

Animals↗

PubMed1986

5-HT1A receptors: differential involvement in female and male sexual behavior in the rat.

The peripheral administration of the serotonin type 1A (5-HT1A) receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH DPAT) inhibited lordosis behavior in ovariectomized rats primed with estradiol benzoate. 8-OH DPAT was ineffective at 0.01 mg/kg, whereas inhibition occurred at the 0.03, 0.1, 0.3, 1, and 3 mg/kg doses. On the other hand, 8-OH DPAT enhanced various measures of male sexual behavior both in males and in females treated chronically with testosterone propionate. In males, 1 mg/kg 8-OH DPAT reduced ejaculation latencies and the number of intromissions prior to ejaculation. In females, 0.1 and 1 mg/kg 8-OH DPAT increased mount frequencies. These data indicate differential involvement of 5-HT1A receptors in male and female sexual behavior. In view of these and other recent data the authors conclude that activity at 5-HT2 receptors facilitates, whereas activity at 5-HT1 receptors may either facilitate or inhibit lordosis behavior. Furthermore, it is proposed that 5-HT1A receptors mediate inhibitory effects, whereas 5-HT1B receptors mediate presynaptic, facilitatory effects of serotonin.

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

PubMed1986

Harmine reverses the inhibition of lordosis by the 5-HT2 antagonists pirenperone and ketanserin in the female rat.

The beta-carboline harmine was found to facilitate lordosis behavior in ovariectomized rats primed with estradiol benzoate. Moreover, harmine reversed the inhibition of lordosis by the serotonin type 2 (5-HT2) antagonists pirenperone and ketanserin in rats primed with estradiol benzoate and progesterone. These results suggest that harmine facilitates lordosis by enhancing activity at 5-HT2 receptors.

Alkaloids↗

PubMed1985

Serotonin antagonist pirenperone inhibits sexual behavior in the male rat: attenuation by quipazine.

Peripheral administration of the serotonin (5-HT) antagonist pirenperone produced a dose dependent inhibition of sexual behavior in sexually naive and experienced male rats. In Experiment 1, both 75 micrograms/kg and 150 micrograms/kg pirenperone significantly reduced the proportion of naive males mounting, while 150 micrograms/kg also reduced the proportion of naive males intromitting and ejaculating. In Experiment 2, both 75 micrograms/kg and 150 micrograms/kg pirenperone significantly increased mount and intromission latencies in sexually experienced males, as well as decreased intromission frequency, with 150 micrograms/kg more potent in each regard. The 150 micrograms/kg dose also increased the post-ejaculatory interval, and decreased both mount frequency and copulatory efficiency. In Experiment 3, both 150 micrograms/kg pirenperone and 3 mg/kg of the 5-HT agonist quipazine produced significant inhibition of male sexual behavior; however, when co-administered, inhibitory effects of each drug were significantly attenuated. The mutual attenuation of effects by a 5-HT agonist and a 5-HT antagonist suggests that the observed effects of both of these drugs were serotonergically mediated. In the final experiment, the 5-HT antagonist ketanserin was shown to inhibit sexual behavior in a manner similar to that of pirenperone. Results suggest a facilitatory, as well as an inhibitory role for 5-HT in male sexual behavior.

Animals↗

PubMed1985

A facilitatory role for serotonin in the sexual behavior of the female rat.

The peripheral administration of the serotonin type 2 receptor (5-HT2) antagonist pirenperone inhibited sexual receptivity in ovariectomized female rats primed either chronically with estradiol benzoate (EB), or acutely with EB plus varying doses of progesterone. An inhibition occurred at 50, 100 and 150 but not 25 micrograms/kg pirenperone. Increasing the dose of progesterone did not attenuate the inhibitory effect of pirenperone. Two other 5-HT2 antagonists, ketanserin (2.5 mg/kg) and spiperone (250 micrograms/kg), also inhibited receptivity in females primed with EB and progesterone. The inhibitory effect of pirenperone on receptivity was attenuated by the 5-HT agonist quipazine (3 mg/kg), though quipazine alone had no effect on receptivity. Whereas the 5-HT antagonist methysergide (3 mg/kg) failed to have an effect on receptivity in EB-primed females, methysergide co-administered with quipazine facilitated receptivity. Pirenperone also inhibited proceptivity in females primed with EB and progesterone. Although quipazine did not attenuate the pirenperone-induced inhibition of proceptivity, quipazine alone increased proceptivity. Moreover, quipazine facilitated proceptivity in EB-primed rats whether progesterone was present or absent. The results suggest that 5-HT may serve both a facilitatory and inhibitory role in female sexual behavior, perhaps reflecting 5-HT2 and 5-HT1 receptor activity, respectively.

Animals↗

PubMed1984

Cholecystokinin-octapeptide produces inhibition of lordosis in the female rat.

The peripheral administration of 3 micrograms/kg CCK-8 produced inhibition of lordosis behavior in ovariectomized female rats primed with estradiol benzoate (EB) and progesterone (P). In Experiment 2, an interaction between CCK-8 and P was evident, with the inhibitory effects of CCK-8 being observed with P doses of 100 and 150 micrograms, but not 250 micrograms. No interaction between CCK-8 and EB was evident, as CCK-8 had no effect on lordosis behavior induced by chronic administration of EB alone. The ineffectiveness of CCK-8 in animals treated with high doses of P, or EB administered chronically, suggests that CCK-8 does not inhibit lordosis via a toxic or non-specific mechanism.

Animals↗

PubMedDate not supplied

The current status of the platelet 5-HT(2A) receptor in depression.

The author reviews the current status of the platelet serotonin (5-HT)(2A) receptor in depression. Considered are studies of receptor binding, and 5-HT-induced platelet activation and aggregation. 5-HT(2A) receptor density tends to increase in depression, although this more clearly relates to suicidality than depression per se. Indeed, data are consistent with the hypothesis that increased density of platelet 5-HT(2A) receptors may be a marker for increased risk of suicide. 5-HT-induced calcium mobilization is enhanced in unipolar depression; however, unlike in bipolar depression, baseline calcium levels are not. Despite inconsistencies, 5-HT-induced aggregation appears inhibited in depression. This may manifest as a relative inhibition, i.e. no change in aggregation response despite a higher density of 5-HT(2A) receptors. The inhibited aggregation response is state dependent, and acute phase proteins or components of the stress response may be factors. It is unclear if differences between depressed and normal subjects in disposition of 5-HT(2A) receptors are generally indicative of traits or states. Nonetheless, there is little evidence that the degree of departure from normal density or activity of platelet of 5-HT(2A) receptors reflects severity of depression.

Blood Platelets↗