The levels and possible involvement of leukotriene B₄ and prostaglandin F_2α in the control of interstitial fluid volume in the rat testis

The possible involvement of two arachidonic acid metabolites, prostaglandin F_2α (PGF_2α) and leukotriene B₄ (LTB₄), in the stimulatory effect of human chorioni gonadotrophin (hCG) on the volume of interstitial fluid (IF) in the rat testis ha been investigated. Administration of hCG caused a time‐ and dose‐dependen increase in the IF levels of PGF_2α while LTB₄ showed no clear dose‐dependence but did decrease significantly at 2–8 h after injection of 100 IU hCG. Administra tion of ethane dimethane sulphonate (EDS), which specifically destroys Leydi cells, decreased the volume of IF but the IF levels of LTB₄ and PGF_2α were unchanged. This indicates that although the absence of Leydig cells results i significant changes in IF volume, LTB₄ and PGF_2α are probably not involved in these changes. Furthermore, these findings suggest that Leydig cells are not th only contributors to LTB₄ and prostaglandins E₂ and F_2α in testicular IF. In rats injected peripherally with hCG, intratesticular administration of the cyclo oxygenase inhibitor, indomethacin, decreased PGF_2α, levels in IF after 2 and 4 ’ 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 o indomethacin + hCG there was a significant increase in IF volume in the indomethacin‐injected testis. It is concluded that, although prostaglandins am LTB₄ are secreted into IF in the rat testis, these arachidonic acid metabolites ar apparently not the primary mediators of the increase in IF volume that follows hCC treatment.