Abstract
BACKGROUND AND PURPOSE: Increased incidence of benign prostatic hyperplasia among insulin-resistant individuals suggests a role for hyperinsulinaemia in prostatic enlargement. We have already reported increased cell proliferation and enlargement of prostate gland in insulin-resistant rats. The present study aimed to elucidate the molecular mechanisms underlying the reversal of prostatic enlargement in insulin-resistant rats by the peroxisome proliferator-activated receptor γ agonist pioglitazone. EXPERIMENTAL APPROACH: Sprague-Dawley rats were fed a normal pellet or a high-fat diet for 12 weeks with or without pioglitazone (20 mg·kg(-1)). Subgroups of animals fed different diets were castrated. Effects of dietary manipulation and pioglitazone were measured on insulin sensitivity, lipid distribution, cell proliferation and apoptosis. KEY RESULTS: A high-fat diet led to the accumulation of fat in non-adipose tissues, insulin resistance, compensatory hyperinsulinaemia and prostatic enlargement in rats. Pioglitazone treatment altered fat distribution, improved insulin sensitivity and normalized lipid and insulin level in rats on the high-fat diet. The improved metabolic parameters led to decreased cellular proliferation and increased apoptosis in the prostate gland. High-fat diet feeding and pioglitazone treatment did not change plasma testosterone levels. However, significant prostatic atrophy was observed in castrated rats irrespective of dietary intervention. CONCLUSIONS AND IMPLICATIONS: Our results show a previously unexplored therapeutic potential of pioglitazone for prostatic enlargement under insulin-resistant condition and further suggest that targeting distribution of lipid from non-adipose tissue to adipose tissue and insulin signalling could be new strategies for the treatment of benign prostatic hyperplasia.