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D Bitran

Publications and source records attributed to D Bitran.

At least 55 records · Page 3Linked to original sources
PubMed1989

Quinelorane (LY163502), a D2 dopamine receptor agonist, facilitates seminal emission, but inhibits penile erection in the rat.

Dopaminergic compounds have been shown to facilitate male sexual responses in various contexts. We investigated the effects of a specific D2 dopamine receptor agonist, quinelorane (LY163502), on sexual responses elicited in the restrained supine male rat (i.e., ex copula reflex tests). Penile erections, evoked by retraction of the penile sheath, were inhibited by systemic administration of 10 micrograms/kg quinelorane; however, the occurrence of seminal emission was dramatically increased. A smaller dose of 0.25 ng/kg was without effect. In a second experiment, intracranial microinjection of quinelorane was followed by ex copula reflex tests. The medial preoptic area (MPOA) has been previously implicated in the dopaminergic regulation of male copulatory behavior. The effects of an intra-MPOA injection of quinelorane on seminal emission and erectile responses were similar to those observed following systemic administration. These results are consistent with the hypothesis that DA receptors in the MPOA are important in the regulation of male sexual behavior and suggest that D2 receptors in the MPOA may decrease ejaculatory threshold while inhibiting erectile mechanisms.

Animals↗
PubMed1988

Microinjection of cis-flupenthixol, a dopamine antagonist, into the medial preoptic area impairs sexual behavior of male rats.

Systemically administered dopamine agonists have been shown to facilitate copulation in male rats. Microinjection of the dopamine agonist apomorphine into the medial preoptic area has also been reported to facilitate sexual behavior. The present experiments investigated the effects of medial preoptic microinjections of the dopamine antagonist cis-flupenthixol on male rat copulatory behavior. Fewer males initiated copulation and fewer ejaculated following flupenthixol administration. Those males that did ejaculate following flupenthixol injections had fewer ejaculations and longer interintromission intervals. Flupenthixol also antagonized the facilitative effects of apomorphine injections into the medial preoptic area. Flupenthixol and apomorphine produced only minor alterations in noncopulatory behaviors. The results suggest that dopamine receptors within the medial preoptic area are important in the regulation of masculine sexual behavior in the rat.

Animals↗
PubMed1988

Relation of autogrooming to sexual behavior in male rats.

Grooming and penile reflexes were studied in male rats that were restrained in supine position with the penile sheath retracted or were free to copulate with sexually receptive females. In Experiment 1 there was a reliable concordance in supine males between the tendency to groom and the tendency to display penile reflexes. In Experiment 2 we analyzed the sequential organization of grooming and genital events in supine tests. It was assumed that many or most episodes of ventral grooming would have been genital grooming had access to the genitalia not been prevented by restraint. Paw grooming tended to precede clusters of penile responses, whereas ventral grooming started after the onset of erections. Experiment 3 was an exploration of grooming in the context of copulation, rather than supine restraint. Males groomed their genitalia immediately after all intromissions and after all mounts that ended mount bouts. The duration of grooming was not affected by whether or not intromission occurred. Finally, in Experiment 4 we observed genital and nongenital grooming and recorded electromyographic (EMG) activity from the striated bulbospongiosus muscle (mBS) of the penis in freely moving rats. Consistently, mBS activity led to genital grooming with a short latency, whereas nongenital grooming rarely led to genital grooming, and EMG activity was not associated with nongenital grooming nor did it tend to follow after genital grooming was initiated.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Inhibition of sexual reflexes by lumbosacral injection of a GABAB agonist in the male rat.

The effects of gamma-aminobutyric acid (GABA) agonists on penile reflexes were investigated. An intrathecal injection of baclofen (0.2, 0.4, or 0.8 microgram), a GABAB receptor agonist, into the subarachnoid space of the lumbosacral spinal cord (L5-S1), resulted in a dose-related decrease in the number of animals responding in a penile reflex test. Doses of 0.2 and 0.4 microgram of baclofen decreased the number of erections; 0.4 microgram also increased the latency to the first glans erection. The highest dose of baclofen (0.8 microgram) completely inhibited penile responses in these tests. None of these doses, however, prevented rats from copulating to ejaculation. Antecedent ejaculation, which facilitated the onset of penile reflexes in saline controls, also blocked the inhibitory effects on penile responses by the lower doses (0.2 and 0.4 microgram) of baclofen, but was ineffective in animals treated with 0.8 microgram baclofen. In contrast to the inhibitory effects of baclofen in the lumbosacral cord, an intrathecal injection of baclofen (0.8 microgram) at thoracic segments (T8-T10) did not affect penile erections elicited following an ejaculation. The role of spinal GABAA receptors in sexual reflexes was assessed by intrathecal injection of a GABAA agonist. THIP (0.5.1. or 2 micrograms), onto the lumbosacral cord. Only at the largest dose of THIP were slight inhibitory effects on penile reflexes observed. Together, these data indicate that stimulation of GABAB receptors in the lumbosacral spinal cord inhibits erectile mechanisms ex copula.

Animals↗
PubMed1988

Brain localization of cholinergic influence on male sex behavior in rats: agonists.

Cholinergic agonists were microinjected into either the lateral ventricle or the preoptic area of sexually experienced male rats. In Experiment 1 carbachol, injected into the lateral ventricles, delayed the initiation of sexual behavior. When injected into the preoptic area, carbachol again delayed the onset of copulation, but these delays were shorter than after ventricular injections. In addition, preoptic injections reduced the number of intromissions preceding ejaculation. In Experiment 2 ventricular injections of the muscarinic agonist oxotremorine again delayed initiation of sexual behavior and also slowed its rate. However, oxotremorine injections into the preoptic area, through cannulae angled to miss all ventricles, only decreased the number of intromissions preceding ejaculation. These data suggest that cholinergic synapses in proximity to the ventricles may decrease sexual arousal, while cholinergic mechanisms in or near the preoptic area may reduce ejaculatory threshold.

Animals↗
PubMed1988

Brain localization of cholinergic influence on male sex behavior in rats: antagonists.

The muscarinic receptor antagonist scopolamine was microinjected into either the preoptic area or the lateral ventricle, preceding sexual behavior tests. In Experiment 1 unilateral ventricular injections of scopolamine delayed the initiation of copulation, while unilateral preoptic injections had no effect. In Experiment 2 bilateral injections into the preoptic area produced dose-related decreases in the percentages of animals intromitting and ejaculating. In Experiment 3 scopolamine, injected alone into the preoptic area, again decreased the percentages of animals mounting, intromitting, and ejaculating. The muscarinic agonist oxotremorine, injected alone into the preoptic area, decreased ejaculatory threshold (i.e., decreased the number of intromissions preceding ejaculation) as previously reported. Concurrent oxotremorine and scopolamine injections into the preoptic area were not different from vehicle; thus, scopolamine blocked oxotremorine's effect. These data suggest that some cholinergic activation of the preoptic area is critical for normal copulation, since bilateral blockade of muscarinic receptors there dramatically decreased the number of animals copulating. However, increased cholinergic activity there only reduced ejaculation threshold.

Animals↗
PubMed1988

Regulation of male rat copulatory behavior by preoptic incertohypothalamic dopamine neurons.

The role of dopaminergic terminals in the medial preoptic area (MPO) in the regulation of male rat copulatory behavior was investigated. A 6-hydroxydopamine (6-OHDA) injection into the MPO of animals pretreated with desipramine resulted in a small (23%) depletion of DA, and no impairment of copulatory activity. Further depletion of catecholamines with alpha-methyl p-tyrosine (AMPT) produced several deficits in the copulatory behavior of 6-OHDA-treated males, at a dose of AMPT that did not adversely affect copulation prior to 6-OHDA administration. The dose-related effects of intracranial apomorphine (APO) injections were also altered by 6-OHDA injections into the MPO. The inhibition previously found with 0.2 microgram of APO into the lateral ventricle of normal males was abolished by 6-OHDA treatment. A facilitation of copulatory behavior was observed following the injection of 0.2 microgram of APO into the MPO of 6-OHDA-treated animals, whereas this treatment did not affect the copulatory behavior of intact animals. Finally, inhibitory effects observed following an injection of 0.1 microgram of APO into the MPO of normal males were blocked by 6-OHDA administration. The relative roles of presynaptic autoreceptors and postsynaptic DA receptors in the MPO in mediating the dose-related effects of APO on copulatory behavior are discussed.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1987

Pharmacological analysis of male rat sexual behavior.

Pharmacological influences on male rat sexual behavior are reviewed in an attempt to identify neurotransmitters and their respective receptor types that regulate various factors comprising the behavioral pattern. Evidence is presented that: (1) serotonergic influence is generally inhibitory to sexual behavior, although two receptor subtypes may lower ejaculation threshold; (2) dopaminergic agonists facilitate several aspects of copulatory behavior and ex copula genital responses; (3) noradrenergic activity appears to increase sexual arousal; (4) cholinergic agonists facilitate ejaculation, or in some cases, delay or prevent initiation of copulation; (5) GABA agonists inhibit sexual responses both in and ex copula; (6) opiate agonists appear to inhibit copulation and penile reflexes, although antagonists have mixed effects; (7) ACTH and MSH peptides promote copulatory behavior and genital responses; (8) oxytocin facilitates ex copula penile responses, but may contribute to postejaculatory refractoriness; and (9) long-term exposure to prolactin inhibits sexual behavior and penile responses. Although some progress has been made in identifying neurotransmitter-receptor effects on behavioral components, copulatory behavior is complex and no drug has been found to affect only a single component. Furthermore, drug specificity is only relative.

Animals↗
PubMed1986

Dopaminergic control of male sex behavior in rats: effects of an intracerebrally-infused agonist.

Systemically-administered dopaminergic drugs have been found to facilitate sexual behavior of men and male rats. The present experiments investigated the localization within the brain of dopaminergic effects on copulation of male rats. Apomorphine, a dopamine agonist, was microinfused into the medial preoptic area, caudate-putamen, nucleus accumbens, lateral septum and lateral ventricle. The lowest dose of apomorphine (0.2 microgram) infused into the ventricle reduced the number of ejaculations, slowed the rate of intromitting and decreased the percentage of mounts on which the male gained vaginal intromission. The higher two doses (0.5 and 2.0 micrograms) infused into the medial preoptic area and, in some cases, the ventricle, increased the number of ejaculations and the percentage of mounts with vaginal intromission, increased the rate of intromitting and decreased the latency to ejaculate and the postejaculatory interval before resuming copulation. Infusions into the caudate-putamen and lateral septum were without effect. Those into nucleus accumbens produced only a slight dose-related decrease in latency to begin copulating. The copulatory impairments associated with infusions of the lowest dose into the ventricle may have resulted from stimulation of autoreceptors, or from preferential stimulation by low doses of an undetermined area. The facilitative effects of the two higher doses into the medial preoptic area and lateral ventricle may have been due to stimulation of dopaminergic postsynaptic receptors.

Animals↗
PubMed1986

Amphetamine-induced anorexia: analysis with hypothalamic lesions and knife cuts.

The present study examined the hypotheses that the midlateral perifornical region of the hypothalamus (PFH), at the level of the ventromedial nucleus, plays a crucial role in amphetamine (AMPH)-induced anorexia and that mediating fibers ascending to this brain region follow a midlateral course through the caudal hypothalamus. Electrolytic lesions that destroyed the PFH region attenuated the feeding suppression induced by intraperitoneal administration of AMPH. Lesions placed anterior, dorsal, or medial to this region, in contrast, did not decrease AMPH's effect. The medially-placed paraventricular nucleus lesion, in fact, enhanced drug response. Midlateral coronal wire-knife cuts in the caudal hypothalamus also attenuated AMPH anorexia. The crucial midlateral caudal hypothalamic cut also disrupted anorexia induced by direct injection of AMPH into the PFH area. The results obtained from the lesion data support the hypothesis that the PFH region is essential to AMPH's suppressive effect upon feeding, and the KC data suggest that crucial catecholamine fibers mediating this drug response ascend specifically through the midlateral portion of the hypothalamus.

Adrenergic Fibers↗
PubMed1984

Perinatal dopamine-related drugs demasculinize rats.

Administration of haloperidol, a common neuroleptic, to pregnant or lactating rats impaired the masculine sex behavior of their male offspring. Prenatal haloperidol did not affect testosterone concentrations in fetuses. Maternal administration of apomorphine, a dopamine agonist, and of alpha-methyl-p-tyrosine, an inhibitor of dopamine synthesis, also demasculinized male offspring. In both experiments other behaviors and developmental milestones were unaffected. Perinatal haloperidol, apomorphine, and alpha-methyl-p-tyrosine did not lower testosterone in adulthood. These drugs may act directly on neurons that control masculine behavior without lowering testosterone prenatally or in adulthood.

Animals↗
PubMed1984

Regional and global left ventricular function during intra-aortic balloon counterpulsation in patients with acute myocardial infarction shock.

We evaluated the improvement in hemodynamic and left ventricular (LV) function in 15 patients with acute myocardial infarction and cardiogenic shock, who were treated with intraaortic balloon counterpulsation (IABP). They were studied by flow-directed right heart catheterization and nuclear angiography. IABP decreased LV end-diastolic volume from 134 to 114 ml and LV end-systolic volume from 100 to 72 ml. LV stroke volume increased from 34 to 42 ml and cardiac output from 3.0 to 3.6 L/min. Global LV ejection fraction increased from 27.6% to 36.1%, and this was due to improvement in regional ejection fraction in ischemic areas. Pulmonary capillary wedge pressure and pulmonary blood volume decreased. Right ventricular ejection fraction also increased significantly. IABP improved LV function in acute myocardial infarction.

Adult↗
PubMed1983

The role of splenectomy in Gaucher's disease.

Thirteen patients underwent splenectomy for Gaucher's disease. All patients were Jewish; 12, of Ashkenazi descent, had the chronic (type 1) form, and one child, of Sephardic (Persian) origin, probably had the intermediate (type 3) form. Hypersplenism was the indication for surgery in 11 patients, mechanical problems in the remaining two. The weight of the resected spleens ranged from 1.06 to 13 kg. Following surgery, hypersplenism (thrombocytopenia in particular) was improved, and the mechanical disturbances were relieved in all patients. There were no deaths and no morbidity related to the operative procedure. Long-term follow-up demonstrated progressive hepatomegaly without evidence of hepatic dysfunction in any of the patients. Bone marrow involvement manifested by osteoarticular complications appeared in five patients. Splenectomy is, we believe, a safe mode of treatment for type 1 Gaucher's disease.

Adolescent↗
PubMed1982

Intraaortic balloon counterpulsation in acute myocardial infarction.

Intraaortic balloon counterpulsation was undertaken in 24 patients with acute myocardial infarction. The patients were divided into four groups: severe left ventricular dysfunction (11 patients), mechanical lesions (6), intractable angina pectoris (6) and refractory ventricular tachycardia (1). The clinical condition and the hemodynamic measurements improved dramatically in 21 patients, but there were only 9 long-term survivors. Intraaortic balloon counterpulsation gave the best results in patients with preinfarction angina pectoris or patients with left ventricular dysfunction where the hemodynamic status deteriorated after an acute but reversible cardiovascular event. Numerous local complications were observed.

Adult↗
PubMed1980

Afterload reduction and cardiac output in patients after mitral valve surgery.

Thirteen patients who had mitral valve surgery were studied within 3 hours after operation. The patients were divided into 2 groups: group A with initial low cardiac index (1.70 +/- 0.25), elevated left atrial pressure (16.5 +/- 6.7) and high peripheral vascular resistance (2623 +/- 789); group B with initial normal cardiac index (3.71 +/- 0.54), normal left atrial pressure (13 +/- 3.5) and normal peripheral vascular resistance (1223 +/- 303). In both groups the mean arterial pressure was elevated (98 +/- 8.8, 96 +/0 15.8). An infusion of nitroprusside to reduce the mean arterial pressure to either 80 mmHg or 10% below the initial value had different effects in each group. In group A, cardiac index (CI) increased by 23%, left atrial pressure (LAP) decreased by 20%, pulmonary artery pressure (PAP) by 35%, and peripheral vascular resistance (PRV) by 32%. In group B, CI decreased by 8%, LAP by 32%, PAP by 30% and PVR by 13%. When LAP returned to initial values after an infusion of blood with continued infusion of nitroprusside, CI increased in both groups (27%, 11%) and the PVR remained lower (40%, 29%). The study demonstrates the favorable effect on cardiac output of vasodilator therapy on patients with elevated blood pressure, impaired by left ventricular function and high LAP, after surgery on mitral valve. The optimal effect is achieved by keeping the LAP within normal limits.

Adolescent↗