Number Of Penile Erections Research Articles

Sexual responses of male rats to odours from female rats in oestrus are not affected by female germ-free status

Rats detect and use odorant molecules as a source of information about their environment. Some of these molecules come from conspecifics, and many arise as by-products from microbial activity. Thus, compared to conventionally housed rats, germ-free rats are raised in an environment with fewer odorants, but this reduction is rarely quantified. Using gas chromatography–mass spectrometry, we found that germ-free rat faeces samples contained half as many volatile molecules than conventional rat faeces (52 vs 109 (±2.4) molecules; P < 0.001) and overall these were only 12% as abundant. We then investigated if odours from female germ-free rats in oestrus would have pro-erectile effects in conventional male rats. For this aim, conventionally housed Brown Norway (BN) rats (n = 16) with sexual experience with either Fischer or BN females, were exposed to four different odour types: faeces from germ-free Fischer rat in oestrus, faeces from conventional rats in oestrus and di-oestrus (either from Fischer or BN), and a control (either 1-hexanol or male rat faeces). The number of penile erections per test as well as the duration of freezing behaviour was significantly higher with the oestrous odours (germ-free and conventional) compared to the control, with intermediate responses to the di-oestrous faeces. The findings indicate that, despite a significantly reduced composition in terms of volatiles compared to conventionally housed rats, the faeces of germ-free rats contain sufficient odorants to evoke sexual responses in conventional male rats. Oestrous odours of rats thus appear not to be of microbial origin.

Achieve Orgasm? Oxytocin Triggers Ejaculation in Men

The paraventricular nucleus (PVN) of the hypothalamus, which is considered to be a centre for autonomic regulation, has been shown to exhibit physiological and functional sex differences. It is involved in numerous functions, from stress to the appetite, body energy balance, blood pressure, heart rate and sexual activity, including penile erection [1], and is characterised by a very complex architecture. OXT is produced chiefly by magnocellular neurosecretory cells in the PVN and supraoptic nucleus of the hypothalamus and released into the blood from the axon terminals in the neurohypophysis and into the surrounding neuropil from magnocellular dendrites [2,3]. The principal functions attributed to OXT are involved in the regulation of reproductive functions including parturition, milk ejection, and sexual and maternal behaviour in females, so called a feminine hormone (for review, see Ref. [4] ). On the other hand, it is well accepted that a group of OXT-ergic neurones originating in the PVN and projecting to extrahypothalamic areas (e.g., hippocampus, medulla oblongata and spinal cord) control penile erection and sexual behaviour in male rats [5]. It has been reported that OXT positively impacted on a number of components of sexual function, including libido, erection, and orgasm in men [6-8]. The intracerebroventricular administration of OXT also induced a dose-dependent increase in the number of penile erections and yawning episodes in male rats, suggesting a physiological role of hypothalamic OXT in the regulation of such responses [9]. Because penile erection and yawning induced by either OXT or apomorphine in rats were antagonised in a dose-dependent manner by pre-treatment with OXT antagonists, dopamine may induce these responses by releasing OXT in vivo [9].

Clavulanic acid: A competitive inhibitor of beta-lactamases with novel anxiolytic-like activity and minimal side effects

Clavulanic acid is a member of the beta lactam family of antibiotics with little or no intrinsic antibacterial activity of its own; instead, it is used to enhance the activity of antibiotics by blocking bacterial beta-lactamases. Because clavulanic acid by itself is very safe, orally active and shows good brain penetrance, we sought to determine if it had any potential as a psychotherapeutic. Clavulanic acid was a tested across three mammalian species, hamsters, rats and cotton-top tamarin monkeys in a series of behavioral assays designed to screen for anxiolytic activity. In addition, several studies were done in rodents to compare the behavioral profile of clavulanic acid to the commonly prescribed benzodiazepines, particularly with respect to their unwanted side effects of motor depression, amnesia and neuroendocrine dysregulation. Our findings show that clavulanic acid is a highly potent anxiolytic in rodents without altering motor activity in the open field test, normal learning and memory in the Morris water maze, or normal stress hormone release. Orally administered clavulanic acid significantly reduces measures of anxiety in male/female pairs of cotton-top tamarins. In addition, male tamarins showed a highly significant increase in sexual arousal as measured by the number of penile erections. The fact clavulanic acid has anxiolytic activity in the tamarin holds the promise that this drug may be an effective therapeutic for the treatment of anxiety disorders in humans.

A novel approach for predicting antidepressant-induced sexual dysfunction in rats

Sexual dysfunction is associated with antidepressant discontinuation. Therefore, there is a need for models that predict antidepressant-induced sexual dysfunction. To develop a predictive method for evaluating antidepressant-induced sexual dysfunction. Male Sprague-Dawley rats were allowed access to sexually receptive females during a single overnight mating session and then treated with antidepressants known to produce differing levels of sexual dysfunction in the clinic. Two to three weeks later, following either acute, subchronic (7-day), or chronic (14-day) antidepressant treatment, rats were observed for penile erections (PE) in the presence of sexually receptive females that were not accessible for contact but served as visual, auditory, and olfactory stimuli in the testing area. Chronic treatment of fluoxetine (10 mg/kg), desipramine (10 mg/kg), and bupropion (20 mg/kg) reduced the number of PE 71, 53, and 8%, respectively, relative to vehicle-treated rats. This rank order of the compounds' propensity for reducing PE is comparable to the rank order of the compounds' ability to produce sexual dysfunction during antidepressant treatment in the clinic. Additionally, drugs used to treat antidepressant-induced sexual dysfunction in the clinic, such as sildenafil, yohimbine, and dopamine agonists, were also effective in attenuating the deficits in the number of noncontact PE produced by chronic fluoxetine treatment. Taken together, this model represents a novel approach for predicting antidepressant-induced sexual dysfunction in rats, which parallels the pattern of reports of sexual dysfunction in the clinic associated with different antidepressant treatments and the ability of adjunct treatment to reverse the sexual impairments produced by antidepressants.