Testosterone primes the MPOA and several other brain areas to release dopamine. MPOA neurons release dopamine strongly during sexual arousal, and the more is released, the more likely a guy cums.In moderate concentrations, dopamine stimulates mostly type D1 andD5 receptors, which facilitate erection of the penis and sexually receptive postures in the female.Dopamine stimulates sexual activity while the neurotransmitter serotonin inhibits it by blocking dopamine release. Levels of testosterone correlate positively with men’s sexual arousal and their drive to seek sexual partners.Applies to females too. Single women have higher testosterone levels than women with a long-term partner.Decreases in testosterone levels generally decrease male sexual activity. However, low testosterone is not the usual basis for impotence, the inability to have an erection. The most common cause is impaired blood circulation, especially in older men.Viagra increases male sexual ability by prolonging the effects of nitric oxide, which increases blood flow to the penis.oFemalesA woman’s hypothalamus and pituitary interact with the ovaries to produce the menstrual cycle, a periodic variation in hormones and fertility over the course of about 28 days.After the end of the menstrual period, the anterior pituitary releases follicle-stimulating hormone (FSH), which promotes the growth of a follicle in the ovary.The follicles nurture the ovum(egg cell) and produces several types ofestrogen, including estradiol.
In the middle of the menstrual cycle, the follicle builds up more and more receptors to FSH, so even though the actual concentration of FSH in the blood is decreasing, its effects on the follicle increase.As a result, the follicle produces increasing amounts of estradiol.The increased release of estradiol causes an increased release of FSH as well as a sudden surge in the release of luteinizing hormone (LH) from the anterior pituitary. FSH and LH combine to cause the follicle to release the ovum.The remnant of the follicle (now corpus luteum) released the hormone progesterone, which prepares the uterus for the implantation of a fertilized ovum. Progesterone also inhibits the release of LH. Progesterone and LH levels continue to increase if a woman gets pregnant, but if not, then both hormones decline, and the lining of the uterus is shed.One consequence of high estradiol and progesterone levels during pregnancy is fluctuating activity at the serotonin 3 receptor, causing nausea. This is why pregnant women get nauseous.Birth control pills prevent pregnancy by interfering with the usual feedback cycle between the ovaries and the pituitary.