Have you ever noticed that your clitoris seems to be engorged more easily around the time of your period? This is because hormonal activity spikes in both men and women during this time.
The rise in testosterone and progesterone stimulates male sexual desire and female receptivity. The same hormones also increase a woman’s fertility, as indicated by the presence of cervical mucus that improves sperm motility and survival.
Testosterone is a member of the group of hormones called androgens that gives men their male characteristics such as growth of body hair, enlarged penis and prostate, changes in voice, and more. It also stimulates the production of red blood cells, strengthens bones and muscles and helps with spermatogenesis.
A gland in the brain called the hypothalamus sends signals to another brain gland called the pituitary gland to instruct it how much testosterone to produce. The pituitary gland then relays these instructions to the testes in a feedback loop.
Testosterone levels can vary based on hormones, age and health status. For example, men who have more sex tend to have higher testosterone levels than those who don’t.
The female sex hormone estrogen is secreted in short bursts throughout the day and night. It is elevated during the periovulatory period of the menstrual cycle, when progesterone levels are low. Estrogens seem to regulate motivation for females to engage in sexual behavior in mammalian species. Behavioral endocrinologists are interested in whether the differences between male and female sexual behaviors and aggressiveness are caused by hormones.
When blood estrogen concentrations are high compared to progesterone, the condition is called estrogen dominance and may be a symptom of polycystic ovary syndrome (PCOS). Estrogen also regulates secondary sex characteristics such as breast development starting at puberty and pubic hair growth in both women and men.
In addition, estrogen affects other areas of the body such as skin and hair, bones and muscles, and even brain function. Studies show that cognitive function declines with age, and this could be a result of low estrogen. Estrogen is used as a treatment for menopausal symptoms, and it has been shown to protect the heart from cardiovascular disease.
Progesterone is a progestogen sex hormone that plays crucial roles in the menstrual cycle and pregnancy. It thickens the uterine lining to prepare for implantation and helps sustain the pregnancy. It also helps breast development and preparing for breastfeeding. It keeps a balance with estrogen, the primary sex hormone in those assigned female at birth, and with testosterone, the primary sex hormone in males. It’s made primarily in the corpus luteum after ovulation and by the placenta during pregnancy. It’s also made in smaller amounts by the adrenal glands and testes in males.
Your healthcare provider can give you supplemental progesterone in different forms, depending on your symptoms and goals. This may include cream or gel suppositories that are applied to the vagina with an applicator similar to a tampon, pills you swallow, and injections. Progesterone is used in hormonal contraception, as part of fertility treatments, and as part of hormone replacement therapy during menopause.
GnRH and its receptors are well known for their role in regulating the hypothalamus-pituitary-gonadal axis. It is a key component of controlled ovarian hyperstimulation in most IVF strategies. It stimulates the synthesis and release of gonadotropins, LH and FSH, which induce estrogen production and ovulation. This results in a higher number of recovered oocytes and lower cycle cancellation rates, leading to better pregnancy rates.
GnRH neurons project to the median eminence and are important for the LH surge that occurs during proestrus. They also project to the midbrain central gray and facilitate lordosis at these sites. These neurons are also known to be involved in female sex behavior.
Besides their role in regulating the hypothalamus-pituitary-gonadal system, GnRH has also been found to suppress stem cells. In one study, GnRH was shown to suppress the proliferation, apoptosis, and migration of human adipose tissue-derived stem cells. This suggests that GnRH may be a universal inhibitor for stem cell function.