Winter Blues or PMS?
Women have a pretty bad rep when it comes to hormones. We get it all the time, in memes, as jokes in TV shows, or in the form of the amusing side comment, “It’s that time of the month again, eh?” with a crass wink. Yes yes, females have a tendency to be moody. For whatever reason, this is a theme present throughout our genetic makeup. A recent study conducted at Indiana University shows that seasonal changes, particularly the fall to winter transition, are associated with a rise in aggressive behavior in female hamsters as opposed to male hamsters. This study revealed new mechanisms by which sex hormones are influenced by the nervous system and provides a model from which we can further study the male and female nervous systems.
The experimenters singled out melatonin as the hormone stimulating female adrenal glands to release hormones acting in place of the hormones released from the gonads. Things do not work this way for male hamsters when there’s a change of season. In females, they found some strange things about this system. The adrenal glands normally release an aggression hormone, DHEA, in response to the release of another hormone, ACTH, secreted by the pituitary gland. Once this seasonal change kicks in however, melatonin is the hormone that stimulates the release of DHEA, and it completely skips past the pituitary gland.
One group of hamsters in this experiment was exposed to the shorter day conditions of winter for ten weeks and then observed for aggressive behaviors. Not only were the female hamsters more aggressive than the males and the control group, but their chemistry had also changed. These aggressive ladies had higher levels of DHEA and melatonin in their bloodstreams and also displayed physical changes in their adrenal glands.
Given that hamsters happen to have similar adrenal systems to humans, these results give us much greater insight into how our own adrenal systems function and how they could be affected throughout the year. While it hasn’t been experimentally proven that these findings can be applied to humans as well, I think it definitely explains away my aggressive feelings during the cold dark months.
~ Jackie Rocheleau
http://www.sciencedaily.com/releases/2015/11/151118070754.htm
http://rspb.royalsocietypublishing.org/content/282/1819/20152080
