The endocannabinoid system in male reproductive organs: expression and localization of fatty acid amide hydrolase (FAAH) in the seminal vesicles and vas deferens
Ueckert, S1; Colciago, G2; Benigni, F2; Bannowsky, A3; Kuczyk, MA4; Hedlund, P5
1: Hannover Medical School, Dept. of Urology & Urological Oncology, Hannover, Germany; 2: University Vita Salute San Raffaele, Urological Research Institute, Milano, Italy; 3: Imland Klinik GmbH, Dept. of Urology, Rendsburg, Germany; 4: Hannover Medical School, Dept. of Urology & Urological Oncology, Hannover, Germany; 5: Lund University, Dept. of Clinical & Experimental Pharmacology, Lund,
Objectives: The endocannabinoid system (ECS), comprising the cannabinoid receptors (CBR), their ligands (anandamide = N-arachidonoyl ethanolamide/AEA, 2-arachidonoyl glycerol = 2-AG, tetrahydrocannabinol = THC), and enzymes controlling the turn-over of endocannabinoids, has been suggested to be involved in male reproductive function. As information is scares on the expression of the ECS in human male reproductive tissues, the present study aimed to investigate by means of molecular biology (RT-PCR) and immunohistochemistry (immunofluorescence) the expression and distribution of Fatty Acid Amide Hydrolase (FAAH, isoforms 1 and 2) in the human seminal vesicles (SV) and Vas deferens (VD).
Material & Methods: Tissue of the SV and VD were obtained from 5 male subjects who underwent pelvic surgery for urological malignancies (carcinoma of the prostate or urinary bladder). Specimens were processed for molecular biology (Polymerase Chain = RT-PCR), Western blot experiments or conventional (laser fluorescence) immunohistochemistry (IHC).
Results: All specimens expressed PCR products corresponding to FAAH1 (260 bp) and FAAH2 (387 bp). Western blot analysis revealed lanes within the expected molecular weight range of FAAH1 (63 kDa) and FAAH2 (58 KD), signals for FAAH1 were more pronounced in preparations of the VD than the SV, while no differences were seen with regard to the expression of FAAH2 protein. IHC using sections of SV and VD displayed cytosolic staining for FAAH1 and FAAH2 in cuboidal cells of all layers of the epithelium, nerve fibers transversing the sections presented only faint staining, while no immunoreactivity was detected in the smooth musculature. In tissue bath studies, the FAAH inhibitor oleoyl ethylamide (OEtA, 0.1 µM - 100 µM) did not exert relevant effects on the tonic contraction of isolated human SV smooth musculature induced by means of alpha-adrenergic stimulation.
Conclusion: Two genes encoding for FAAH (FAAH1 and 2) are present and highly expressed in the human SV and VD. Considering its localization, the enzyme might be involved in the control of epithelial homeostasis and secretory function rather than in the mechanism of mechano-efferent signaling.
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