The Durk Pearson & Sandy Shaw®
Life Extension NewsTM
Volume 16 No. 9 • October 2013


Protective Effects of Astaxanthin on Capillary Blood Flow in Muscles of Mouse Model of Couch Potatoes

Despite the proven benefits of exercise, there are still an awful lot of people who don’t exercise, including those who don’t think they have the time or others that simply don’t enjoy exercising. For those people (and we include ourselves among those who would rather spend our time reading, writing, or thinking than doing boring exercises), protecting our muscles from atrophy due to being sedentary is an important priority in maintaining good health. A new paper1 reports protective effects against decreased capillary blood flow in the muscles of rats as a result of disuse by the carotenoid astaxanthin.

The researchers explain that capillary regression in skeletal muscles is associated with decreased muscular activity as a result of increased oxidative stress and this results in reduced blood flow in the affected muscles. The researchers hypothesized that astaxanthin, a powerful antioxidant that is stronger than vitamin E under a number of stress conditions, might reduce this oxidative stress and ameliorate the capillary regression associated with muscle disuse.

They used a common experimental model of muscular disuse where the hindlimbs of the rats were suspended by the tail so that there was no weight bearing on the hindlimbs and, hence, those muscles were not subject to contractions that activate pathways induced by exercise. The effects are very similar to extended bedrest. The researchers explain that these “unloaded” hindlimbs have been shown to have lower levels of VEGF (vascular endothelial growth factor) that supports the blood vessels that, in active muscles, maintain blood flow.

The results showed that the VEGF protein level was lower in the hindlimb suspended group than in both control groups (in one of the control groups, rats were not hindlimb suspended and in the other control group, rats were not hindlimb suspended but did receive astaxanthin supplementation), but that the VEGF protein level in the hindlimb suspended rats supplemented with astaxanthin, the VEGF level was not different from the two control groups. In fact, the authors found that all angiogenic (blood vessel growth promoting) factors, except ANG-2, were higher in the the hindlimb suspended + astaxanthin group than the hindlimb suspended (no astaxanthin) group. The decreased angiogenic factors in the hindlimb suspended group that did not receive astaxanthin resulted in regression of capillaries.

In this study, astaxanthin treatment prevented the decrease in capillary volume and shift towards smaller diameter capillaries that occurred in the disused hindlimb muscles but did not prevent the decrease in muscle mass that resulted from the decreased hindlimb loading. Therefore, the mechanisms responsible for the decreased capillary capacity and the decreased muscle mass must be different.

Though the researchers did not examine the effects of astaxanthin on blood vessel capacity in the heart in this experiment, it would be of considerable interest to see whether astaxanthin would help maintain capillary volume in the heart of sedentary animals or people. Exercise is known to provide beneficial results to heart capillary blood flow (collateral blood flow) and this may very well be due to similar angiogenic factors as astaxanthin maintained in the hindlimb suspension model.

Reference

  1. Kanazashi et al. Protective effect of astaxanthin on capillary regression in atrophied soleus muscle of rats. Acta Physiol (Oxf). 207:405-15 (2013).

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