Species with approximately equal numbers of reproductively active males and

Species with approximately equal numbers of

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Successive introductions of new females can maintain this behavior. Species with approximately equal numbers of reproductively active males and females less likely to have this, but more common a single male group. If a male rat is castrated (testes removed), his sexual activity eventually ceases. Behavior can be reinstated by injections of testosterone. Sexual behavior of male rodents depends on testosterone. Injections of testosterone increase weight of seminal vesicles in castrated rats. Testosterone: neural basis of this activational effect. Hormonal Control of Sexual Behavior Oxytocin secreted by posterior pituitary gland Oxytocin -- contraction of the smooth muscle of the milk ducts, the uterus, and the male ejaculatory system Oxytocin -- also serves as a neurotransmitter in the brain. It is also produced in males, where it plays no role in lactation. Hormonal Control of Sexual Behavior Oxytocin is released at the time of orgasm in both males and females and appears to contribute to the contractions of the smooth muscle in the male ejaculatory system and of the vagina and uterus. Oxytocin – also involved in pair bonding. Hormonal Control of Sexual Behavior Prolactin is also involved in male sexual behavior. Prolactin is released by anterior pituitary and stimulates milk production in females. In males it contributes to refractory state. Hormonal Control of Sexual Behavior Hyperprolactinemia: excess prolactin This hypersecretion can be due to a prolactin-secreting tumor, pregnancy, or the use of numerous medication Men – hallmark symptom – loss of libido Side Effects of Psychotropic Medications Many psychotropic medications including SSRI’s have side effects including reduced libido and sexual dysfunction. Recent study found chronic use of painkillers also displays this effect increased prolactin Hormonal Control of Sexual Behavior In some rodent species,, females adopt a posture that exposes her genitals to the male during estrus -- receptive period in the estrous cycle. Lordosis: spinal sexual reflex: arching of the back in response to approach of a male or to touching the flanks, which elevates the hindquarters. Hormonal Control of Sexual Behavior
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