The predominant androgen in men,<unk> , has shown to substantially decline throughout the aging process. The decline in both serum and total<unk>  with age have been linked to several disease states in men. In particular, cardiac failure and ischemic heart disease have been linked to this natural biochemical decline in<unk> . Previously, the higher<unk>  risk in men has been attributed in part to the negative effects of systemic<unk> , however, more recent research has highlighted the protective nature of<unk>  against<unk>  disease. The magnitude and mechanism of action by which low<unk>  in men is influential in the pathogenesis of<unk>  risk and the potential benefits of<unk>  therapy has yet to be fully determined. __TOC__
Testosterone and the cardiovascular system
Adipose-derived hormones
Sympathoadrenal system
Hypothalamic–pituitary–thyroid axis
Hypothalamic–pituitary–somatotropic axis
Hypothalamic–pituitary–gonadal axis
Parasympathetic nervous system
Hypothalamic–pituitary–prolactin axis