Estrus, Rabbits, and You: The Endocrinology of Easter

People have often told me that I talk "smart." It's because of my parents. I was born shortly after my mother received her Master's degree, and my father was doing post-doctoral work at UCONN. Mom was going to be a high-school science teacher, and Dad's dissertation had something to do with reproductive endocrinology.

Ever since I was an infant, they've been speaking to me in the same language they used with their peers, be they doctoral candidates, chemists, or professors. At no time was I shown a "choo-choo." I was shown a steam engine, accompanied by an explanation of what made it different from a coal engine or a diesel engine.

I loved them for this. It may sound stuffy, but we had a lot of laughs growing up. As the years progressed, the little science lessons of life grew increasingly detailed and complex. By the time I was in college, Dad and I were discussing the most recent research into the pharmacology of various medicines and their appropriateness in this disease syndrome or that. Invariably we would begin to hypothesize, our imaginations spiraling off into the absurd. I spent a lot of weekends visiting home during college, and Dad was usually the one to shuttle me to and fro. During the 90-minute drives, we'd be laughing so hard our faces would be red and puffy by the time we pulled up to the house.

I emailed my parents a photo of the Easter Eggs I made last night. My father responded this morning with the following email:

You know, of course, that the word, "Easter," comes from the same root as the words, "Estrus," and "Estrous Cycle." The former refers to sexual receptitivty in the female and the latter to the reproductive cycle in some mammals that is similar to the menstral cycle. For example rats and pigs have estrous cycles.

Rabbits, interestingly, do not have either estrous cycles or menstrual cycles. They are induced ovulators. That is, stimulation of the uterine cervix triggers what is known as a neuroendocrine reflex arc. Stimulation of the cervix sents an afferent message to the rabbits's hypothalamus. In turn it releases gonatropic releasing factor which drips on the pituitary gland which releases luteinizing hormone which gets to the ovary and causes ovulation. The viability of the sperm is four days, so there is sufficient time for some of those millions or sperm to find their home.

Humans, of coure, are sponataneous (cyclic) ovulators. However, while I was a graduate student, it was found that primates probably ovulated both ways, induced as well as cyclic. As a matter of fact, we were going to get young married couples to have sex in the lab and measure to see if we could find luteining hormone afterward in increased amonts. We want to pay them, say $100.00 (a lot of money at the time) a piece. Someone accused us of a pun.

Anyway, it is now long established that humans can be induced to ovulate from coitus. This is the reason Vatican Roulette is not always effective as a birth control method.

By the way, the rabbit predates the resurrection as a Spring celebration by millenia.

Love,

Dad

I called him to thank him for the outstanding analysis, and expressed enthusiasm for the proposed study of increased lutenizing hormones in sexually active humans. Dad mentioned that, sadly, none of his colleagues had done their doctoral dissertation on this study.

I agreed that this was tragic. "They could have gotten class credit for getting laid!"

Happy Spring, everyone. Be sure to celebrate in an appropriate fashion!