To examine the potential of steroid hormones to serve as putative regulators of aortic cell function, we defined hormone receptor content and distribution in intact baboons. Total androgen receptor content in baboon aortic arch, thoracic arch, and abdominal aorta of young mature males was indistinguishable from that of proestrus females. However, 30% to 40% of male aortic androgen receptors were in the nuclear fraction, whereas all aortic androgen receptors of proestrus females were in the cytoplasmic fraction. Cytoplasmic fraction estrogen receptor content of aortic arch and thoracic aorta of intact males was indistinguishable from that of proestrus females. However, cytoplasmic fraction estrogen receptor content of abdominal aorta of proestrus females was significantly greater than that of males. Nuclear fraction estrogen receptors were not detectable in either male or proestrus female baboon aortas. To assess effects of endogenous estrogen on aortic progesterone receptor content, we quantified cytoplasmic fraction progesterone receptors and found that content of proestrus female aortic arch was not significantly different from that of males. However, cytoplasmic fraction progesterone receptor content of thoracic and abdominal aorta of proestrus females was significantly higher than that of males. To determine whether differences in aortic receptor content or distribution were associated with changes in aortic cell function, we quantified the activity of two enzymes of glycosaminoglycan metabolism. Aortic β-glucuronidase activity was not difference in male or proestrus female baboons. Uridine diphosphate glucose (UDPG) dehydrogenase activity of aortic arch and thoracic aorta of proestrus female baboons was not different from that of males; however, UDPG dehydrogenase activity of abdominal aorta of proestrus females was greater than that of males. Our studies establish endogenous androgen regulation of intracellular distribution of baboon aortic androgen receptors and imply that these receptors are physiologically functional. The higher cytoplasmic fraction progesterone receptor content of female thoracic and abdominal aorta, as compared to that of males, suggests aortic estrogen receptors also are physiologically functional. These findings establish that baboon aortic steroid hormone receptor content and distribution is sexually dimorphic, as is the case for rodents. However, the essential identity of β-glucuronidase or UDPG dehydrogenase activity in male and female baboon aortas indicates that baboon aortic glycosaminoglycan metabolism is not sexually dimorphic. The fact that aspects of aortic steroid hormone receptor homeostasis and steroid hormone regulation of aortic UDPG dehydrogenase and β-glucuronidase activity significantly differ in baboons and rodents implies complex effects of steroid hormones which may be species-specific.
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine