Evil Monkey's second post on Oxytocin, this one on effects of Oxytocin on females. It's a know fact that Oxytocin and females are like "peas and carrots", nevertheless its fascinating to learn how a single hormone can have such a profound impact on who we are (excluding the life long social and cultural impact). Here's a effects of Oxytocin on different stages of a females life:
"Birth:
In pregnant women, oxytocin has one of it's major roles (you might say it's the most important, but given the importance of the OTHER roles of oxytocin, it's a toss-up). Oxytocin is released at the end of fetal development (and sometimes during), and results in uterine contraction, making it one of the most important hormones at birth (the other one is progesterone, which gets HUGE right before birth).
In pregnant women, oxytocin has one of it's major roles (you might say it's the most important, but given the importance of the OTHER roles of oxytocin, it's a toss-up). Oxytocin is released at the end of fetal development (and sometimes during), and results in uterine contraction, making it one of the most important hormones at birth (the other one is progesterone, which gets HUGE right before birth).
The coolest thing about oxytocin during parturition is that it's controlled under a positive feedback cycle. Goes like this (in the very, very simplified version):
1) Baby is big and heavy, and presses against the cervix.
2) Cervix feels the burn and stretches a little.
3) The muscle stretching of the cervix triggers receptors which send nerve impulses to the brain.
4) Brain releases oxytocin.
5) Oxytocin further softens and dilates the cervix.
6) Baby weight pushes downward on the softened cervix and stretches it.
7) Lather, rinse, repeat.
8) BABY!!!
2) Cervix feels the burn and stretches a little.
3) The muscle stretching of the cervix triggers receptors which send nerve impulses to the brain.
4) Brain releases oxytocin.
5) Oxytocin further softens and dilates the cervix.
6) Baby weight pushes downward on the softened cervix and stretches it.
7) Lather, rinse, repeat.
8) BABY!!!
"Positive feedback" is the stretching of the cervix which promotes oxytocin, which promotes stretching, which promotes MORE oxytocin. The actions of the hormone trigger the release of more hormone. If you're like Sci, you will think this is really, really cool.
However, oxytocin is not necessarily NEEDED for birth. There are oxytocin knockout mice that do not have oxytocin and can still reproduce (but these are knockout animals, and so growing up without oxytocin, their bodies could compensate). But it's very clear that oxytocin is very important in the normal birth process. In fact, it's SO important that oxytocin analogues (drugs that mimic oxytocin, such as Pitocin) are used to induce labor, and oxytocin receptor antagonists (which block the actions of oxytocin, like the drug Tractocile) are used to stop premature labor and uterine contractions. So, pretty important.
Lactation:
You can see up there the important things for oxytocin, the alveoli (those little frond things), the milk sinus (also known as the sac), and the nipple opening, which is surrounded on the outside by the areola, which is the dark area of the nipple. While other hormones (like prolactin) are involved in actually MAKING milk, oxytocin is very important for releasing it, in what's known as the let-down reflex.
Goes like this (again, the simplified version, the complicated version involves dopamine and a host of other hormones):
1) Baby sucks at nipple
2) The sensation of suckling heads to the brain (skipping some detailed steps here).
3) The hypothalamus is stimulated and oxytocin is released from the posterior pituitary.
4) Oxytocin in this case acts to contract the muscles around the alveoli in the breast.
5) The squeezed alveoli deliver milk to the milk sinus via the duct.
6) Baby sucks, milk comes out.
1) Baby sucks at nipple
2) The sensation of suckling heads to the brain (skipping some detailed steps here).
3) The hypothalamus is stimulated and oxytocin is released from the posterior pituitary.
4) Oxytocin in this case acts to contract the muscles around the alveoli in the breast.
5) The squeezed alveoli deliver milk to the milk sinus via the duct.
6) Baby sucks, milk comes out.
Orgasm:
Oxytocin is actually important in sexual arousal for both men and women (I'll cover more about the men in the next post). During sexual arousal, oxytocin increases rapidly, with a big burst at orgasm. In fact, in women, the strength of orgasm is directly correlated with the amount of oxytocin. Oxytocin levels correlate to sexual arousal in women, as well as the amount of vaginal lubrication present. Not only that, oxytocin fluctuates along with a woman's menstrual cycle, being highest in the ovulatory phase and follicular phase, and lowest in the luteal phase (The follicular phase and ovulatory phase are the preparation and release of the egg, respectively, and fertility will peak at ovulation for obvious reasons. The luteal phase is the phase after ovulation, as the egg sits around and grows old until the shedding of the uterine lining during menstruation at the end of the month. Sci will probably have to blog about this sometime).
Oxytocin is actually important in sexual arousal for both men and women (I'll cover more about the men in the next post). During sexual arousal, oxytocin increases rapidly, with a big burst at orgasm. In fact, in women, the strength of orgasm is directly correlated with the amount of oxytocin. Oxytocin levels correlate to sexual arousal in women, as well as the amount of vaginal lubrication present. Not only that, oxytocin fluctuates along with a woman's menstrual cycle, being highest in the ovulatory phase and follicular phase, and lowest in the luteal phase (The follicular phase and ovulatory phase are the preparation and release of the egg, respectively, and fertility will peak at ovulation for obvious reasons. The luteal phase is the phase after ovulation, as the egg sits around and grows old until the shedding of the uterine lining during menstruation at the end of the month. Sci will probably have to blog about this sometime).
So oxytocin is very important physically, helping us enjoy the procreation of the species and allowing the species to get out of the womb and get fed.
Maternal bonding:
This is the part where some people get antsy. For it's true, oxytocin DOES influence behavior. Oxytocin DOES promote things like affiliative behavior with one's young.
This is the part where some people get antsy. For it's true, oxytocin DOES influence behavior. Oxytocin DOES promote things like affiliative behavior with one's young.
Examples: rats, once they give birth, will pick up pups and carry them around. They'll build a nest for them (if they haven't already), and lick them and basically associate with them like good rat mommies. However, if you give a rat mom something to block oxytocin, she will not pick up the pups, carry them around, or make a nest. Giving oxytocin to sheep will induce maternal behavior by sheep for lambs that are not their own, even if the sheep has never given birth.
So when it comes down to it, yes, we're influence by our hormones. But we are ALSO under the influence of human society and the environmental influences coming in through our vast prefrontal cortex. And to discount the incredible influences of society and the cortex would be very naive indeed."
The point is if we "know" our hormones, we can change ourselves for better depending deficiency or abundance of a hormone, in addition to the perpetual social sways life brings. I think lot of the this can be achieved sans any pills by understanding more on who we are and interpret that knowledge in the process of self reflection.
"The saddest aspect of life right now is that science gathers knowledge faster than society gathers wisdom." - Isaac Asimov
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