The levels and possible involvement of leukotriene B4 and prostaglandin F2α in the control of interstitial fluid volume in the rat testis

Abstract

The possible involvement of two arachidonic acid metabolites, prostaglandin F2 alpha (PGF2 alpha) and leukotriene B4 (LTB4), in the stimulatory effect of human chorionic gonadotrophin (hCG) on the volume of interstitial fluid (IF) in the rat testis has been investigated. Administration of hCG caused a time- and dose-dependent increase in the IF levels of PGF2 alpha while LTB4 showed no clear dose-dependence, but did decrease significantly at 2-8 h after injection of 100 IU hCG. Administration of ethane dimethane sulphonate (EDS), which specifically destroys Leydig cells, decreased the volume of IF but the IF levels of LTB4 and PGF2 alpha were unchanged. This indicates that although the absence of Leydig cells results in significant changes in IF volume, LTB4 and PGF2 alpha are probably not involved in these changes. Furthermore, these findings suggest that Leydig cells are not the only contributors to LTB4 and prostaglandins E2 and F2 alpha in testicular IF. In rats injected peripherally with hCG, intratesticular administration of the cycloxygenase inhibitor, indomethacin, decreased PGF2 alpha levels in IF after 2 and 4 h but not at later times. However, no inhibitory effect of indomethacin on the hCG-stimulated increase in IF volume was detected; indeed, at 2 h after injection of indomethacin + hCG there was a significant increase in IF volume in the indomethacin-injected testis. It is concluded that, although prostaglandins and LTB4 are secreted into IF in the rat testis, these arachidonic acid metabolites are apparently not the primary mediators of the increase in IF volume that follows hCG treatment.