A mechanism for testosterone modulation of alpha-1 adrenergic receptor expression in the DDT1 MF-2 smooth muscle myocyte

Abstract

Previous reports have confirmed that steroid hormones modulate the expression of adrenergic receptors on the surface of smooth muscle myocytes. The present study was undertaken to evaluate the mechanism by which testosterone modulates alpha-1 adrenergic receptor expression in the DDT1 MF-2 transformed smooth muscle cell. Utilizing 3H-prazosin radioligand binding studies, alpha-1 adrenergic receptors were noted to increase more than 2 fold in response to incubation with 10(-8)M testosterone for 96 hours. Dihydrotestosterone similarly stimulated a significant increase in alpha-1 receptors; whereas, estradiol and hydrocortisone appeared to suppress the expression of this receptor in DDT myocytes. The testosterone effect was dose related with a maximal response observed in response to 10(-7)M testosterone at both 48 and 96 hours. Kinetic experiments utilizing 10(-8)M testosterone demonstrated a peak effect on alpha-1 receptor expression at 96 hours, and maintenance of the effect for at least 168 hours (7 days). The testosterone effect was completely prevented at both 48 and 96 hours by inhibition of transcription with actinomycin-D, or inhibition of translation with cycloheximide. Consistent with the receptor binding studies, RNA blotting studies have demonstrated maximal alpha-1 receptor mRNA levels at 48-96 hours of testosterone stimulation. In conclusion, these in vitro experiments have confirmed the physiologic concentrations of testosterone stimulate the increased expression of alpha-1 receptors in the DDT1 MF-2 myocyte after a delay of 48-96 hours; and that this effect appears to be mediated by transcription, translation, and synthesis of new proteins in these genital tract myocytes.

Testosterone Effects on Renal Norepinephrine Content and Release in Rats With Different Y Chromosomes

“…27 Testosterone has been shown to stimulate the increased expression of ␣ 1 -receptors in myocytes grown in tissue culture after 48 to 96 hours because of synthesis of new proteins. 28 In the central nervous system, peripheral testosterone also modulates NE metabolism. For instance, testosterone implants similar to those used in our study reduced NE turnover in the basal hypothalamus.…”

Testosterone-augmented contractile responses to α1- and β1-adrenoceptor stimulation are associated with increased activities of RyR, SERCA, and NCX in the heart

“…1) as well as the activity of Ca 2ϩ -regulatory proteins, we used perfused hearts isolated from control, ORX, and ORX ϩ T (200 g/100 g body wt) rats. In the series of experiments that examined the underlying [Ca 2ϩ ]i homeostasis and the role of the androgen receptor, testosterone at physiological relevant concentrations (10 Ϫ8 M) (46,60) was administered to the same batch of myocytes isolated from ORX rats for 24 h (ORX ϩ T; 10 Ϫ8 M). To confirm the effects of testosterone and ␣1-or ␤1-adrenoceptor stimulation on [Ca 2ϩ ]i transients were indeed ␣1-or ␤1-adrenoceptor mediated, we administered the ␣1-or ␤1-adrenoceptor antagonist to the ORX ϩ T group, respectively (see Fig.…”

Review of the Y chromosome and hypertension

“…Testosterone also increases s-adenosylmethionine, a major cellular methylator, and may influence the catecholamine pathway (54). The rate-limiting enzyme for the catecholamine pathway, tyrosine hydroxylase, and NE concentration in the abdominal aorta and mesenteric artery were decreased by castration and restored by testosterone in SHR but not in WKY (50). The mechanism for this effect could either be directly on the neurons or through tissue trophic factors.…”