Findings from a recent study published in the European Journal of Pharmacology may explain why Raynaud’s is more common in women of childbearing age. The study examined the relationship between palm blood flow and estrogen in mice. According to researchers, "estrogen may contribute to the development of Raynaud's phenomenon in women".
Estrogen is a one of two main sex hormones that women have. It is responsible for female physical features and reproduction. Estrogen creates the changes common in puberty, such as growth of the breasts, hair in the pubic area and under the arms and the beginning of menstruation. The hormone helps control the menstrual cycle, protect bone health and keep cholesterol in control. Below is a helpful infographic Hormone Health Network to help you understand what estrogen is.
About Raynaud's phenomenon
Raynaud's phenomenon is a condition in which there is an exaggerated blood vessel tightening in response to cold or emotional stress, restricting blood flow to certain areas of the body-most often the fingers, but sometimes the toes, ears, or the end of the nose. Affected areas generally first turn white in colour, and then may become blue then red. Researchers from the study explained that "the reduced blood flow in hands and feet when people are exposed to cold is controlled both by nerve signals by what is known as the sympathetic nervous system, and by local processes constricting blood vessels."
Raynaud's phenomenon affects approximately 3 to 5 percent of the population - women more commonly than men.
Raynaud's phenomenon has several warning signs, which may be present at the onset of disease. These include:
- Fingers, toes, ears, and/or nose turning white or blue when they are exposed to cold, or at times of emotional distress
- Pain in the fingers or toes when they are exposed to changes in temperature
- Tingling in extremities when they have been exposed to cold and are warming up
Once a doctor has diagnosed Raynaud's phenomenon, there are several simple, effective methods to help manage the symptoms. While there is no known cure for Raynaud's phenomenon, people with the disease are usually able to manage their symptoms with medications and behavior modification.
There are a number of strategies to treat the symptoms of Raynaud's phenomenon. Most importantly, protecting the core body (hat, scarf, layered clothes) as well as the hands and feet from cold temperatures will help prevent discomfort. Wearing gloves and heavy socks in winter is a simple protection strategy. Some people with Raynaud's phenomenon even find it helpful to wear cotton gloves or oven mitts reach into freezers, to protect sensitive hands and reduce the risk of vasospasms.
People with Raynaud's phenomenon should not smoke or be exposed to second-hand smoke, as smoking restricts blood vessels and can exacerbate the condition.
About the research
The research was conducted by the University of Shizuoka in Japan. They explained that the most common effects of estrogen involve actions directly on cells' DNA, where it binds to genes to control their activation, and that estrogen can also act on receptors on the cell surface.
To explore only the actions of estrogen that are not affected by gene effects, researchers conducted research on the mice with the scenarios below. The mice were then put to sleep with a foot exposed to temperatures that dropped from 25℃ (77℉) to 10℃ (50℉) in five-degree increments.
- To reduce the impact of natural hormonal fluctuations, researchers used female mice that lacked ovaries. The mice were then given a compound that blocked the signalling from the sympathetic nervous system. The cooling reduced blood flow when the mice were injected with estrogen and the effect of the cold temperature was boosted. The higher the concentration of estrogen, the more restricted the blood flow.
- Researchers blocked a receptor involved in the local blood vessel constriction response. Estrogen did not increase the effect of the cold temperature.
- The mice were treated with a compound that stimulated one of the receptors estrogen is known to bind. Researchers found that "stimulating the receptor also increased the reduction in blood flow", whereas, blocking the receptor "prevented the hormone from reducing the blood flow."
In conclusion, the study's experiments show that estrogen likely contributes to Raynaud's phenomenon by affecting local molecular events that constrict blood vessels.