Effects of obesity in rats on prostate histology and expression of leptin receptor, prolactin receptor, IL-6, and NF-κB.

Background: Hypercaloric intake can lead to obesity, which is a major risk factor associated with chronic subclinical inflammation and many types of cancer. It can increase the serum levels of leptin, prolactin, nuclear factor kappa B (NF-кB) and interleukin (IL)-6, implicated in cell proliferation, differentiation and survival.

Aim: To explore the effects of obesity induced by chronic hypercaloric diet in rats on the long-term expression of leptin receptor (OB-R), prolactin receptor, NF-кB, and IL-6, and the changes of histology in rat prostate.

Materials and methods: From postnatal day 21, experimental males were fed with normal chow or chow plus enriched hypercaloric liquid diet. On the postnatal day 90 (13 week old), the animals were euthanized for prostate histology (hematoxylin and eosin staining) and hormone receptors analysis by Western blot.

Results: Hypercaloric diet resulted in obesity (32% higher body weight). The prostates of the obese males showed epithelium anisocytosis and compressed interstice. There was also greater volume of lipidic content, anisokaryosis, alterations of the nucleus-cytoplasm ratio, and apparent proplasia. Measures in the ventral prostate (VP) showed that alveoli area increased, but epithelium height and nucleus area were reduced. In the dorsolateral prostate, there was only reduction of nucleus area and presence of mononuclear cells in the lumen. Hypercaloric males also expressed a trend for more OB-R 130 kD in the VP, but no changes were observed with regard to prolactin receptor, NF-кB and IL-6.

Conclusion: The obesity due to chronic consumption of hypercaloric diet affects both prostatic regions, but VP is possibly more sensitive via OB-R. We suggest that longer periods of obesity are needed to alter other receptors or the molecular markers of inflammation.