(There is another hormone, called vasopressin, which plays a stronger role in bonding for men.) This anti-social effect of a social hormone brings some nuance to the story of oxytocin.
In people assigned male at birth (AMAB), oxytocin plays a part in ejaculation. The hormone contracts the vas deferens to push sperm and semen forward for ejection. Oxytocin also affects the production of testosterone (a sex hormone) in the testes.
Do both men and women produce oxytocin? Yep, but women typically have higher oxytocin levels than men. (It's a key hormone involved in childbirth and lactation, after all). Biological differences aside, men and women appear to experience oxytocin in many of the same ways.
Vasopressin also plays a major role in defensive behaviors such as mate guarding. Both males and females are affected by oxytocin and vasopressin (Carter, 2017). However, the physiological effects of vasopressin support physical mobilization and defensive aggression, which may be especially critical in male mammals.
Nerve cells at the base of the brain (hypothalamus) make and transport vasopressin to the pituitary gland, which then releases the hormone into the blood stream. Pain, stress, and certain drugs — such as opiates (narcotics) — can trigger the release of vasopressin.
Physical attraction, sexual compatibility, empathy, and emotional connection are key to making a man fall in love with a woman.
There are two major stimuli for ADH release: elevated plasma osmolality and decreased effective circulating volume. Increased plasma osmolality causes shrinkage of a specialized group of cells in the hypothalamus called osmoreceptors.
Oxytocin and vasopressin are the hormones most closely associated with romantic love. They are produced by the hypothalamus and released by the pituitary gland; and while men and women are both influenced by oxytocin and vasopressin, women are more sensitive to oxytocin and men are more sensitive to vasopressin.
The cuddle hormone
Men also have oxytocin, but it is compensated for by higher levels of testosterone - so they are less prone to cuddling!
These results suggest that oxytocin injected into the VTA induces penile erection by activating NO synthase in the cell bodies of mesolimbic dopaminergic neurons. NO in turn activates guanylate cyclase present in these neurons, thereby increasing cyclic GMP concentration.
Men have been shown to be particularly sensitive to physical contact, so touch likely boosted their oxytocin levels considerably, Melton says. “Justifying small ways to make any activity one where we're touching our partner, whether that's touching of the arm or around the shoulder, [could be useful],” Melton says.
Certain neurotransmitters and hormones need to build up over time before a man or woman falls in love. According to love biologist Dawn Maslar, the chemicals dopamine and vasopressin are vital for a man to start falling in love, whereas it's oxytocin and dopamine for women.
More precisely, oxytocin induces penile erection when injected unilaterally into the caudal area but not into the rostral ventral tegmental area in a dose-dependent manner [88].
Oxytocin, also known as the love or bonding hormone, promotes feelings of intimacy and closeness. The body releases it after orgasm.
"Studies in voles have shown that the hormone vasopressin is released in the brain of males during mating," Walum explained. Vasopressin activates the brain's reward system, and "you could say that mating-induced vasopressin release motivates male voles to interact with females they have mated with," Walum said.
Ethanol and caffeine reduce vasopressin secretion. The resulting decrease in water reabsorption by the kidneys leads to a higher urine output. Coffee is an example of a food product that suppresses the body's release of antidiuretic hormones, due to its level of caffeine.
Oxytocin and vasopressin are two neuropeptides that have been extensively studied for their systemic and physiological roles. Studies in rodents show that oxytocin and vasopressin play an opposite role in several behavioural and physiological tests for anxiety and fear.
Drugs that stimulate the release of ADH from the posterior pituitary gland include nicotine, phenothiazines, and tricyclics. Some drugs increase or potentiate the renal action of ADH. They include desmopressin, oxytocin, and prostaglandin synthesis inhibitors.
Posterior Pituitary Hormones
However evidence supports the idea that exercise is a potent stimulus for ADH secretion. During periods of heavy sweating and intense exercise, ADH works to minimise the extent of water loss from the kidneys, thereby decreasing the risk of severe dehydration.
An increased osmolality draws water from cells into the blood thus dehydrating specific brain osmoreceptors that stimulate drinking and release of anti diuretic hormone (ADH or vasopressin).
Contrary to popular belief, women don't fall in love quickly. Actually, science said in relationships between cisgender men and women, men are more likely to declare love at first sight. A new study found men actually fall in love quicker than women, and the reason could be biological.