Gender, hyperandrogenism and vitamin D deficiency related functional and morphological alterations of rat cerebral arteries.

Abstract

Hyperandrogenism is a risk factor of cerebrovascular diseases as androgens can alter markedly the regulation of cerebrovascular tone. We examined the combined impact of androgen excess and vitamin D deficiency (VDD), a common co-morbidity in hyperandrogenic disorders, on remodeling and testosterone-induced vascular responses of anterior cerebral arteries (ACA) in order to evaluate the interplay between androgens and VDD in the cerebral vasculature. Male and female Wistar rats were either fed with vitamin D deficient or vitamin D supplemented diet. Half of the female animals from both groups received transdermal testosterone treatment. After 8 weeks, vessel lumen, wall thickness and testosterone-induced vascular tone of isolated ACA were determined using pressure microangiometry and histological examination. Androgen receptor protein expression in the wall of cerebral arteries was examined using immunohistochemistry. In female rats only combined VDD and testosterone treatment decreased the lumen and increased the wall thickness of ACA. In males, however VDD by itself was able to decrease the lumen and increase the wall thickness. Vascular reactivity showed similar alterations: in females, testosterone constricted the ACA only after combined VDD and hyperandrogenism, whereas in males VDD resulted in increased testosterone-induced contractions in spite of decreased androgen receptor expression. In conclusion, a marked interplay between hyperandrogenism and VDD results in inward remodeling and enhanced testosterone-induced constrictions of cerebral arteries, which might compromise the cerebral circulation and thus, increase the risk of stroke in the long term. In addition, the early cerebrovascular manifestation of VDD appears to require androgen excess and thus, depends on gender.