PCOS & Brown Adipose Tissue

Polycystic ovarian syndrome otherwise commonly referred to as PCOS is one of the most common endocrine diseases effecting women of reproductive age. At the fundamentals of the disease, PCOS is diagnosed based on these three components known as the Rotterdam Criteria:

 

  1. Biochemical or clinical hyperandrogenism (excess testosterone or DHEA in your system)
    • Looks like: cystic acne, facial hair, deepening of voice
  2. Oligomenorrhea
    • infrequent, irregular and unpredictable periods
  3. Polycystic ovaries visualized via Ultrasound
    • Multiple ovarian cysts produced from immature follicles

 

You only need two out of the three criteria two be diagnosed with PCOS. By laying out the diagnosis in three “check boxes” so to speak, makes the pathology seem more straightforward then it actually is. A huge component of this pathology and is not included in the diagnostic criteria is the element of insulin resistance and how that interplays with all three of the Rotterdam Criteria in a very “Chicken or Egg?” relationship.

 

For more information on the pathophysiology, signs and symptoms and other contributing factors that make PCOS so complex, please give my colleague Dr. Courtenay Boer’s post on PCOS a read over.

For the remainder of this post, I wanted to highlight some current research coming out on PCOS that provides a new perspective on the disease as well as has the potential to guide future treatment.

 

Through random chance, earlier this week I attended a research presentation seminar at the local university on a hormone Dr. Sarah Gray had been studying and the role it plays on brown fat/thermogenesis and extrapolating that back to how that may influence obesity and diabetes. I went home from that lecture, feeling inspired having taken in all this new information and perspective on metabolism, energy intake and expenditure (and with a new intellectual crush!) – to pop on my Instagram and see my other intellectual crush, Dr. Fiona McCulloch, had just written a post discussing a recent study on the role brown fat may play in PCOS!

Pretty crazy timing of it all.

I took this as a sign that I need to dig into this topic more, and I stumbled upon this neat study, that Dr. McCullough also references in her post, on brown fat and PCOS.

 

To catch you up to speed, first of all – what is brown fat?

The human body is composed by a couple different types of fat: majority being white fat, but there is also brown fat, and a category called “beige fat” which is white fat that has the capacity to turn into brown fat.

White fat – this makes up majority of the adipose tissue on the human body. In general, when “body fat” is discussed or referred to, we are talking about the white fat on the human body. It is a storage form for triglycerides, provides us with insulation and protection, and is also hormonally active.

Brown fat – a category of fat that is metabolically active to produce heat to keep the body warm (thermogenesis). Currently under investigation for its hormonal activity and role it may play in PCOS, diabetes, obesity and much more!

Click here for a study with more information on White & Brown Fat

Coles Notes on the study I stumbled upon and wanted to share with you!

  • Female rats were injected with DHEA (a type of androgen) or Placebo
    • The DHEA injected group then developed PCOS
  • After PCOS had been evaluated as established in the DHEA injected rats, they then received a transplant of brown adipose tissue from a rat without PCOS
  • Three weeks after the transplant of the brown adipose tissue into the PCOS rats, via PET-CT demonstrated that the brown adipose tissue was just as active in the brown adipose tissue transplanted group as it was in the control group in comparison to the DHEA-induced PCOS rat group that did not receive the brown adipose transplantation
  • The group of rats that had DHEA induced PCOS, but did NOT receive a brown adipose tissue transplant showed decreased brown adipose tissue gene expression as well as a decrease in thermogenesis after eating their meals
  • The DHEA injected group that received the brown adipose tissue transplant demonstrated normalized blood sugar control (similar pattern to the control group) in comparison to the DHEA injected group that did not receive the brown adipose transplant
  • The DHEA injected group that received the brown adipose tissue transplant demonstrated regulation of menstrual cyclicity in 7 / 10 rats
  • The study also looked at the role of adiponectin
    • Found that it was decreased in human PCOS and DHEA-induced PCOS in rats
    • Injected adiponectin into the DHEA-induced PCOS rats as well as subjected them to a cooler temperature to induce thermogenesis (activity of brown adipose tissue) and found that the injections of adiponectin in combination with the cooler temperature was able to increase the endogenous brown adipose tissue in the DHEA-induced PCOS rats
    • This is important – “these results highlight that the beneficial effects of brown adipose tissue transplantation are partly mediated by an elevated circulating adiponectin (hormone) level”

To summarize: By transplanting brown adipose tissue into the DHEA-induced PCOS rats, there was an improvement in insulin sensitivity and cycle regularity – two MAJOR symptoms of PCOS. There was no noticeable difference in BMI of the PCOS and control rat groups.

Click here to read the full study I am referring to..

 

What does this mean for you and me?

 

Given the response of the DHEA-induced PCOS to the transplant of healthy brown adipose tissue – and that as a stand-alone factor having the capacity to change systemic insulin sensitivity and regulate a cycle hints towards a major role brown adipose tissue and the hormone adiponectin may have to play in the pathogenesis of PCOS.

 

Also notable – the study Dr. McCullough discusses in her post evaluates HUMANS as the study subjects The study I’ve been talking about is looking at the response in rats, which the theory can be extrapolated to humans being that we are both mammals, however we need to keep in mind that humans are not going to respond 100% the same as rats.

 

To wrap this post up, there is still more research needed to be done to understand the intricacies of brown adipose tissue and the role it may play within the complex condition that is PCOS. As a practitioner in the women’s health field, it is exciting though to learn about another factor I should be considering with my patients with PCOS and future research on this topic will better guide me in treating my PCOS patients and help me address all aspects of the condition.

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