Metabolic Syndrome Enhances Prostate Contractility and In Vitro Phenylephrine-induced α1 -Adrenoceptor Protein Expression in the Fructose-fed Rat.

Objectives: To study the effects of metabolic syndrome on prostate α-adrenergic contractile function using fructose-fed rats (FR).

Methods: Age-matched male Wistar rats were divided into two groups: group I, normal control rats; and group II, 9-week FR. Animal body weight, blood pressure and serum metabolic parameters were monitored. The prostate was removed 9 weeks after induction of metabolic syndrome in the FR. The contractile responses of prostatic strips to phenylephrine (10(-7) to 10(-6) M) and KCl (50 mM) were tested. Prostate α1 -adrenoceptor (α1 -AR) protein expression was studied by Western blotting analysis with a polyclonal antiserum.

Results: At week 9, the FR showed significant increases in body weight, blood pressure, plasma glucose, insulin and triglyceride levels. The FR prostate weight was significantly higher than that of the controls (610.5 ± 13.2 vs 422.3 ± 7.7 mg, P < 0.05 for n = 8). FR prostate contractile responses to phenylephrine and KCl were both significantly increased. Interestingly, prostate α1 -AR protein expression level was lower in the FR. However, after in vitro 10(-6) M phenylephrine stimulation, FR prostate α1 -AR protein expression was significantly increased.

Conclusion: Metabolic syndrome in FR significantly increases prostate contractile responses to KCl and α-adrenergic stimulation. Paradoxically, FR prostate α1 -AR protein expression is decreased, but significantly enhanced after in vitro phenylephrine stimulation.