Basic FGF partially prevents degeneration of paraventricular vasopressin neurons after hypophysectomy

This experiment was designed to determine if basic fibroblast growth factor (bFGF) had neurotrophic effects on vasopressin neurons after hypophysectomy. Adult male Sprague-Dawley rats received 1 μg bFGF (bFGF group) or 0.1% bovine serum albumin (BSA group) to the sellar cavity immediately after hypophysectomy via parapharyngeal approach. Seven sham-operated non-hypophysectomized rats were used as control. Later (7 weeks) the number of arginine vasopressin (AVP) neurons was quantitatively examined in the paraventricular nucleus (PVN) and the supraoptic nucleus (SON) by immunohistochemistry. AVP neurons in both the PVN and SON of the hypophysectomy groups exhibited a significant reduction in number, compared with the control group. In the PVN, the number of AVP neurons was significantly greater in the FGF group than in the BSA group. Particularly, the difference was confirmed in the posterior magnocellular division, that consists of AVP neurons mainly projecting their axons to the posterior pituitary. In the SON, however, there was no difference in the number of AVP neurons between the bFGF group and BSA group. These results suggest that bFGF has a preserving effect on AVP neurons in the PVN following hypophysectomy.