Previous month:
October 2006
Next month:
December 2006

Oxytocin and HRT

If a woman's estrogen level plummets during menopause, and estrogen enhances the effects of oxytocin, it seems likely that her enjoyment of all the benefits of oxytocin will suffer. While the balance of risks and benefits of hormone replacement therapy remains unclear, there is clear evidence that HRT increases oxytocin after The Pause.

A study led by Kathy Light at the University of North Carolina, found that women taking estrogen replacement therapy had higher levels of an oxytocin precursor in their blood, leading to lower blood pressure under stress.

Studies of ovariectomised rats by Kirsten Uvnas-Moberg were convincing enough that she left her post as a professor at Stockholm's Karolinska Institute to found a company to develop oxytocin-based treatments for menopausal symptoms.

The "menopausal" rats had higher insulin levels and higher blood sugar. Lower levels of cortisol and growth hormone meant they had less energy. They also gained more weight than untreated rats. Five days of oxytocin treatments reversed these effects, normalizing insulin levels; the rats treated with oxytocin for ten days didn't gain as much weight, eating the same amounts of food as the fatties did.

Some of that weight gain could be down to hormonal changes in appetite, also due to less oxytocin running through the veins. Researchers at the University of Pittsburgh found that mice without the oxytocin-producing gene had a sweet tooth, consuming a lot more sweetened water than normal mouse kept under the same conditions.  They also hankered after salt  -- bring on the potato chips!

But rats in Uvnas-Moberg's lab that got estrogen along with oxytocin fared even better. They had lower levels of stress hormones and higher levels of growth hormones than rats that got oxytocin alone.

The body of a menopausal woman may not be able to make the most of her everyday supply of oxytocin. HRT could boost its effects, but, whether or not she goes that route, there are plenty of strategies to naturally boost the oxytocin response.

The Joy of Giving

In his Deep Freeze 9 blog, Pierre de Vries wraps up news of some interesting  oxytocin research  -- which was published  just in time for the holidays.

Researchers found that donating money activated the same areas of the brailn that light up for food, sex and drugs. It also activated the oxytocin receptor-rich area that creates the bond between mother and child.

Animal Love

Do animals feel love?  Some of us instinctively "know" this, while others say that's merely assigning human traits to animals.

Jonathan Balcome, author of the new book "Pleasurable Kingdom: Animals and the nature of Feeling Good" decided five years ago that animals do feel enjoyment and wrote the book to make his argument. According to Seattle Times writer Michael Bradbury,
Oxytocin, a hormone associated with human social bonding, is just as important in giving mother animals the inclination to care for their babies.

"Nature is replete with signs of parental love," Balcombe says, offering examples. Orca mothers watch as their calves explore and play. Chimpanzee infants cradle and groom logs as part of the transference of their mothers' love."

Well, that may be enjoyment, but it's not a "higher-order emotion," some scientists scoff.

Yet, not only mammals but birds and even earth worms share many of the elements of human biochemistry that play our bodies into emotion. We now know that the brain releases norepinephrine  when we're sexually attracted to someone and dopamine when we touch them.When we have sex, dopamine stimulates the brain's reward center while oxytocin stiumulates receptors there and in the parts of the brain used for social memory. Those chemicals feel like love to us.

In the article,

"[Scoffer and biologist Jim] Ha concedes that "to a degree" scientists can see animal brains respond the same way human brains respond in similar situations. But high-resolution brain scans only capture simple, physiological emotions that involve the release of specific brain chemicals.

And it feels good. A monkey probably doesn't think, "Oh, I'm in love." But she wants to do it again.