Edwin Lephart explains how removing estrogen in rats causes obesity and metabolic changes. Estrogen replacement reverses the weight gain. Both estrogen receptor alpha and beta contribute, with alpha as the primary regulator in fat tissue and beta affecting the brain's control of metabolism and movement.
If you were to take a rat model and take away all the estrogen, then the animal gets obese. If you give back estrogen, then you can control that obesity. And when women experience menopause, one of the common challenges is that they gain weight, along with increased challenges in skin health and wrinkle formation, etc. Because of the loss of estrogen. But if you look at the receptor subtypes, alpha and beta, alpha seems to be the important estrogen receptor in fat as far as the major modulator or control factor. However, when they've knocked out estrogen receptor alpha in animal models and then they gave estrogen to induced obese animals, they also lost weight. And so the concept was, even though estrogen receptor alpha is the major receptor for controlling fat deposition, the ER beta component is also very important. And it's not only for the fat tissue site, but it's also for the hypothalamic influence of having molecules that would regulate metabolic hormones like thyroid. Because in other studies we've seen that thyroid slightly increases associated with a decrease in body weight. And also with the hypothalamic connection, there seems to be an increase in activity, meaning the animals move more, there's more locomotor activity. As we've talked about before, there's multiple actions to equal in binding ER beta having influences at the hypothalamic level and at metabolic hormone levels too.
