Expression of nerve growth factor in the prostate of male rats in response to chronic stress and sympathetic denervation

Abstract

Nerve growth factor (NGF) has been found in the normal prostate of the Wistar rat and is regarded as an important prostatic mitogen. We have previously shown that chronic stress induced epithelial hyperplasia while sympathetic denervation caused atrophy in the male Wistar rat prostate. NGF may have been a contributing mechanism to the hyperplasia and atrophy response that was observed. The aim of the present study was to investigate the expression of NGF in the prostate of the male rat in response to chronic stress and denervation. Two weeks of restraint water-immersion stress were used to induce a chronic stress model in Wistar rats. Denervation of the peripheral sympathetic nerve was induced by 6-hydroxydopamine. The expression levels of NGF in the dissected prostate lobes were examined by immunohistochemistry. After 14 days of stress, proliferation of the epithelium in the ventral lobes was observed, whereas the dorsolateral lobes were almost unaffected. NGF immunoreactive protein was localized to the columnar secretory epithelium lines of the prostate tissue. Stress and denervation led to an increase in NGF expression in the ventral lobes. In conclusion, NGF was involved in the hyperplasia and atrophy in the prostate of the male rat in response to chronic stress and sympathetic denervation, and thus may be a contributing factor in the pathophysiology of the prostate.

Keywords: Wistar rat; chronic stress; nerve growth factor; prostatic disease; sympathetic denervation.

Figure 1

Expression of NGF in the prostatic lobes of male Wistar rats. (A) Ventral prostate of an untreated control rat. (B) Proliferation of the epithelium in the ventral prostate of a WIRS-treated rat, characterized by intraluminal villous enfolding, as well as the appearance of epithelial nodules, piling up of epithelial cells and a loss of cell polarity. NGF expression is increased. (C) Ventral prostate of a 6-OHDA-treated rat showing dilated acini and a significant increase in NGF level. (D) Ventral prostate of a WIRS plus 6-OHDA-treated rat without proliferation. (E) Negative control. All images were captured using the same magnification (original magnification, ×200; bar, 100 μm) and stained using Hematoxylin-Eosin. NGF, nerve growth factor; WIRS, restraint water-immersion stress; 6-OHDA, 6-hydroxydopamine.