ACCUMULATION OF VARIOUS N-ACYLETHANOLAMINES INCLUDING N-ARACHIDONOYLETHANOLAMINE (ANANDAMIDE) IN CADMIUM CHLORIDE-ADMINISTERED RAT TESTIS

Changes in the levels of various molecular species of N-acylethanolami ne in CdCl2-administered rat testis were examined. We found that the l evels of various N-acylethanolamines including anandamide (N-arachido- noylethanolamine), an endogenous cannabinoid receptor ligand, were dra matically increased in CdCl2-administered rat testis. Such changes wer e particularly prominent for saturated and monoenoic species such as N -palmitoyl species (39-fold at 9 h) and N-stearoyl species (al-fold at 9 h), compared with unsaturated fatty acid-containing species such as anandamide (5-fold at 9 h). Noticeably, increased levels were observe d of not only N-acylethanolamines but also several species of N-acylph osphatidylethanolamine, potential precursors for N-acylethanolamines. We confirmed that the rat testis microsomal fraction contains phosphod iesterase activity catalyzing the release of N-acylethanolamine from N -acylphosphatidylethanolamine and transacylase activity catalyzing the formation of N-acylphosphatidylethanolamine from phosphatidylethanola mine and phosphatidylcholine. These enzyme activities were not dramati cally different in the microsomal fraction obtained from CdCl2-adminis tered rat testis compared with that in the case of control rat testis, at least when estimated in cell-free assay systems, suggesting that t he accessibility of the substrates to the enzymes may be increased in CdCl2-administered rat testis to generate a large amount of N-acyletha nolamine. Possible pathophysiological implications of the augmented ge neration of N-acylethanolamine including anandamide in CdCl2-administe red rat testis were discussed. (C) 1998 Academic Press.