Over the last several weeks, I have been looking at the role of estradiol in mitochondrial health. In the first post Hormones, Hysterectomy and the Aging Brain, we learned that estradiol depletion wreaks havoc on brain mitochondria turning them into misshapen donuts and blobs. Digging a little deeper, the next post (Lupron, Estradiol and the Mitochondria) pondered the connection between estradiol-depleting drugs such as Lupron, other Lupron-like drugs, and the devastating side effects that often follow suit. Could Lupron-mediated mitochondrial damage be at the root of these side effects? Quite possibly? A question that remains is how. In this post, I will be digging even deeper into the role of estradiol in mitochondrial functioning, especially its role in something called metabolic flexibility.
A note of caution, while I focus on estradiol, the mitochondria, and what happens to health when we remove estradiol pharmaceutically via Lupron or surgically via oophorectomy, it is important to remember that estradiol is not the only hormone synthesized in the ovaries nor are the ovaries the only hormone-producing tissues. Moreover, the chemical castration induced by Lupron and other medications or via ovary removal disrupts and diminishes the synthesis of a myriad of hormones. Estradiol is simply where most of the research is focused, and so, it is where I too must focus, at least for the time being.
Steroid Hormones and Metabolic Flexibility: A Critical Factor in Post Lupron and Post Oophorectomy Ill Health
Steroid hormones regulate metabolic flexibility at the level of the mitochondria. Estradiol, the most frequently studied among the steroid hormones, plays a pivotal role in determining how food fuel is converted into cellular fuel or ATP. When we eliminate estradiol with medications such as Lupron and other GnRH agonists or antagonists, or when we remove a woman’s ovaries, depleting her primary source for estrogen synthesis, metabolic flexibility diminishes significantly. With the lack of metabolic flexibility comes several health issues, some noticeable, like weight gain, and others less noticeable, at least initially, like cardiac and neurodegenerative diseases. A common component of each of these conditions is mitochondrial dysfunction. Mitochondrial dysfunction can be initiated and accumulated via a number of mechanisms and over time, so estradiol is not the only variable, but it is a key factor that is often ignored.
Mitochondria are the cellular powerhouses that consume oxygen and transform the foods we eat into a currency that cells can use (ATP) to perform all of the intricate tasks needed for survival and health. Mitochondria are also the site of steroidogenesis (steroid synthesis), immune signaling, and all sorts of other functions that determine cellular life and death. When you think about it, how well the mitochondria perform these tasks affects health at every level of organismal physiology. Without the appropriate amount of mitochondrial energy/ ATP, cell function becomes deranged, and ultimately, grinds to a halt. When that happens, disease is imminent. Indeed, genetic perturbations of mitochondrial function are some of the most devastating diseases known to medicine.
One has to wonder, what happens when we perturb mitochondrial function from the outside in – via toxicant exposure or by eliminating critical hormones or other co-factors such as nutrients that are necessary to mitochondrial operations? Worse yet, what if an individual with unrecognized genetic defects in mitochondrial functioning faces additional mitotoxicant exposures; what then? Complex, multi-system disease – that’s what. I would argue that mitochondrial dysfunction represents the final common pathway, a convergence point, connecting an array of seemingly disparate disease processes. Mitochondrial metabolism, and specifically, metabolic flexibility, may be at the heart of the derangement, with estradiol, and likely other hormones, in the driver’s seat.
Metabolic Flexibility: Adapt and Survive
When we think of stress and flexibility in general terms, it is easy to recognize that the more flexible one is in his/her behaviors or coping mechanisms, the easier it is for one to respond to, and survive stressors. Flexibility means that options exist for when everything hits the fan. Imagine if there were no options or if you had to respond to each and every stressful event in your life using exactly the same behaviors or response patterns. You would not get very far. The same holds true for cell behavior, and more specifically, mitochondrial behavior. The mitochondria need options to respond to the differing needs of the cells that they supply with energy. If those options become limited in any way, the mitochondria become less effective. They produce less energy, scavenge fewer oxidants (toxicants), and when stressors present, cannot easily adapt. In fact, the more inflexible the mitochondria are forced to become, the less likely they, and the cells, tissues, organs, and organism within which they reside, will survive. Estradiol is integral to mitochondrial flexibility. Remove the estradiol and the mitochondria become less metabolically flexible and less able to respond to the demands of a changing environment.
Estradiol Equals Increased Mitochondrial Efficiency and Decreased ROS
Estradiol maintains metabolic flexibility via two important mechanisms: increased mitochondrial efficiency and ROS management. With the former, estradiol regulates metabolic flexibility by altering the expression of genes that control the enzymes within the fuel conversion pathways. It is a complex algorithm of responses, with some proteins upregulated and others downregulated. The net result, however, favors increased efficiency in ATP production by maximizing metabolic flexibility or adaptability to the environment.
With the latter, estradiol, along with progesterone, manage the clean-up tasks inherent to any energy production process. In effect, estradiol manages ROS both on the front end and the back end of mitochondrial ATP production. On the front end, increased metabolic efficiency and flexibility equals fewer ROS byproducts. On the backend, estradiol cleans up the byproducts of processing -ROS – and tempers the damage these byproducts can cause.
Estradiol, Pyruvate, and ATP
Of particular interest to our work here at Hormones Matter, estradiol upregulates a set of enzymes called the pyruvate dehydrogenase complex, PDC. The PDC, responsible for converting glucose into pyruvate, is the first step in the long process that nets multiple units of mitochondrial ATP. The PDC is key to carbohydrate metabolism and more recently has been linked to fatty acid metabolism, making this enzyme complex central to mitochondrial energy production. Diminished PDC derails mitochondrial functioning, producing serious diseases. Children born with genetic pyruvate dehydrogenase deficiency suffer serious neurological consequences and rarely live to adulthood.
Importantly, the PDC (like all of the enzymes within these cascades) is highly dependent upon nutrient co-factors to function properly. Thiamine and magnesium, are critical to the PDC complex. Since PDC function demands thiamine, children and adults with thiamine deficiency also suffer significant ill-health, ranging from fatigue and muscle pain, to disturbed cognitive function, disrupted autonomic function affecting multiple organs, psychosis, and even death if not identified. Thiamine deficiency is most well known as a disease associated with chronic alcoholism but has recently begun re-emerging in non-alcoholic populations relative to medication and vaccine reactions. Many medications and environmental variables deplete thiamine and magnesium, diminishing mitochondrial function significantly, by way of pyruvate.
Along with nutrient co-factors, estradiol is critical for pyruvate. Estradiol upregulates the expression of the enzymes that make up the PDC (in the brain). If estradiol is reduced or blocked, mitochondrial ATP production will take a hit. If estradiol is blocked in an already nutrient-depleted woman, the first step in mitochondrial fuel conversion would take a double hit. One can imagine the consequences.
In light of the direct role that thiamine, magnesium, and other nutrients play in the cascade of reactions required to produce ATP, can we maximize mitochondrial functioning with nutrients to compensate for the mitochondrial damage or deficiencies likely to occur post oophorectomy or as a result of GnRH agonist or antagonist drugs, like Lupron? I can find no research on the subject, but it is certainly a topic to explore given the millions of women already suffering from the mitochondrial damage induced by Lupron and/or pre-menopausal ovary removal. Even without the necessary research, correcting nutrient deficiencies and dietary issues should be undertaken for general health.
Another question in need of exploration, if we maximize mitochondrial functioning, does that then increase steroidogenesis in other endocrine glands? A section of the adrenal glands called the zona reticularus, for example, produces a complement of hormones similar to those of the ovaries. In postmenopausal women androgens, precursors for estradiol, produced by the adrenals account for a large percentage of total estradiol production. Could we take advantage of that to help stabilize circulating hormones?
Finally, beyond the nutrient requirements for mitochondrial ATP production, enzymes throughout the body, even those involved in post-mitochondrial steroid metabolism, require nutrient co-factors to function properly. Could we maximize those enzymes for more efficient steroid metabolism to net sufficient estradiol to maintain mitochondrial function?
What about Natural Declines in Estradiol?
It is not clear how menstrual cycle changes in estradiol affect mitochondrial functioning or how the postpartum decline in pregnancy hormones affects mitochondria. One would suspect there are compensatory reactions to prevent damage, but this has not been investigated. In natural menopause, however, researchers have noted that some form of compensation occurs as estradiol declines and, at least for a time, and in rodents, mitochondria maintain efficient production of ATP. In contrast, no such changes are noted with premature menopause or oophorectomy.
Also not investigated sufficiently, is the impact of chronic synthetic estrogen exposure on mitochondrial functioning. In other words, what are the effects of oral contraceptives, HRT, and the growing list of environmental endocrine disruptors, on mitochondrial ATP production? Since these compounds bind to estrogen receptors and displace the endogenous estrogens like estradiol, some evidence suggests endogenous production of estradiol is reduced. Do the mitochondria respond also by downregulating estrogen receptors or by some other mechanism? Short-term, animal research suggests that supplementing 17B estradiol post oophorectomy reduces mitochondrial damage. In research in humans, where synthetic estrogens are used, results are less clear and longer-term studies do not exist beyond the broad brush strokes of epidemiology.
Metabolic Flexibility and Tissue Type
One of the more interesting aspects of estradiol’s role in metabolic flexibility is that it is site or tissue-specific and may point to novel therapeutic opportunities. Since different cell types, in different parts of the body, prefer different fuels for power to survive, when we eliminate estradiol from the equation, mitochondria from different tissues or organs respond differently to the lack of flexibility. Perhaps, we can utilize the information about fuel requirements to design diets that compensate for diminished metabolic flexibility.
Heart Cells. I’ve written about this research previously, not fully understanding the implications. Estradiol allows cardiomyocytes (heart cells) to switch from their preferred fuel of fatty acids to glucose during stressors such as heart attacks (and theoretically during any stressor like exercise). That ability to switch fuel types is protective and allows the cells to survive and heal. It may explain why women are more susceptible to heart damage post-menopause when endogenous estradiol declines. This may also point to a pathway for post oophorectomy and post Lupron declines in normal heart function.
Brain Health. Declining estradiol affects brain mitochondria differently. As I noted in a previous post, without estradiol, brain mitochondria become progressively less functional and misshapen. These structural changes impair mitochondrial ATP production. Unlike the heart, however, the brain prefers glucose as its primary fuel source. Estradiol appears to enhance glucose uptake from the periphery and across the blood-brain barrier. When estradiol is absent, brain glucose uptake diminishes significantly (in rodent studies), leaving the brain perpetually starved for glucose.
We know from brain cancer research, that with declining brain glucose, secondary fuels can kick in, but only when the mitochondria have sufficient flexibility to switch. For example, mitochondrial fuel flexibility is critical to battling brain tumors. Under conditions of stress and when brain glucose concentrations are low, healthy mitochondria can readily transition to ketone bodies for energy, at least in vivo. The transition from glucose to ketone bodies is believed to be an evolutionary adaptation to food deprivation allowing the survival of healthy cells during severe shifts in the nutritional environment. Estradiol appears to be key in maintaining that flexibility.
Weight Gain and Fat Accumulation. Post-menopausal, post-hysterectomy, and oophorectomy weight gain are well established research findings. Anecdotal complaints of Lupron weight gain are also common. These findings may be related to derangements in metabolic flexibility mediated by the relationship between estradiol and mitochondrial functioning. The increased lipid or fat accumulation in skeletal muscle though associated with impaired insulin-stimulated glucose metabolism may be related to the reduced capacity to adjust to a changing fuel environment. More specifically, weight gain may represent a declining ability to utilize fats effectively as a mitochondrial fuel source, possibly via a derangement in a mitochondrial channel responsible for shuttling fats and cholesterol into the mitochondria for processing. When the mitochondria become less flexible, a channel called the TSPO, shuts down, disallowing fats that would normally be shuttled into the mitochondria and processed for ATP (and steroid hormones), from entering. Instead, they are stored peripherally in adipocytes. I wrote about this in detail here: It’s All about the Diet: Obesity and Mitochondrial Dysfunction. It is possible in estradiol-depleted women that TSPO downregulation is a compensatory reaction to diminished metabolic flexibility.
It is also conceivable that the lack of brain glucose, as discussed above, leads to overeating and, more specifically, cravings for sugary foods. This would be a logical compensatory reaction to bring more fuel to the brain; one likely meant only for the short term and that when held chronically begins the cascade of other metabolic reactions known as obesity, diabetes, and heart disease. Perhaps, just as fat storage becomes a survival mechanism when mitochondria can longer process it effectively, the craving for sugar in estradiol-deprived women is also a survival mechanism.
Finally, adipocytes can synthesize estradiol. It is conceivable that in response to declining estradiol concentrations, the body stores fat to produce more estradiol.
Central to mitochondrial dysfunction, whether by genetic predisposition or environmental influence, is the inability to efficiently produce ATP (the fuel that all cells need to survive) and to effectively manage the by-products of fuel production and other toxicants. Estradiol plays a huge role in both of these processes. Eliminate estradiol and mitochondrial functioning becomes less efficient and less flexible initiating cascades of chronic and life-altering conditions. This suggests the ready application of medications like Lupron that deplete estradiol or the prophylactic removal of women’s ovaries is misguided at best, and dangerous at worst.
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This post was published originally on Hormones Matter on February 11, 2015.