Bathgate R A, Sernia C
Department of Physiology and Pharmacology, University of Queensland, St Lucia, Australia.
J Endocrinol. 1994 May;141(2):343-52. doi: 10.1677/joe.0.1410343.
In this study oxytocin (OT) receptors have been characterized and localized in the testis of the rat using the radioiodinated OT receptor antagonist 125I-labelled d(CH2)5 [Tyr(Me)2,Thr4,Tyr9-NH2]-vasotocin (OTA). Receptor density and localization have been compared with the rat testis arginine vasopressin (AVP) receptor using the radioiodinated AVP V1a receptor antagonist 125I-labelled d(CH2)5Sar7-AVP and the radioiodinated linear AVP V1a antagonist 125I-labelled [(C6H5-CH2CO)-O-methyl-D-Tyr-Phe-Gln-Asn-Arg-Pro- Arg-Pro-Arg-Tyr-NH2]. 125I-labelled OTA bound with high affinity to membrane fractions of the rat testis (Ka = 13.8 +/- 1.25 litres/nmol), mammary tissue (Ka = 20.3 +/- 4.36 litres/nmol) and uterus (Ka = 27.8 +/- 0.74 litres/nmol). Competition studies with various OT and AVP receptor agonists and antagonists confirmed that the binding was to OT receptors. AVP receptors in the testis were found to be identical to AVP V1a receptors in the liver. The AVP receptor density in the testis was much higher than the OT receptor density (109 +/- 12.3 vs 5.2 +/- 0.79 (mean +/- S.E.M.) fmol/mg protein). Autoradiographical localization showed that both OT and AVP receptors were present in the interstitial spaces in the testis consistent with binding to Leydig cells. AVP receptors were also localized on the epithelial surfaces of the seminiferous tubules and on testicular blood vessels. This study has, for the first time, found OT receptors in the testis of the rat which have similar ligand-binding characteristics to mammary and uterine OT receptors. The receptor localizations are consistent with binding to Leydig cells.
在本研究中，使用放射性碘化催产素（OT）受体拮抗剂125I标记的d(CH2)5 [Tyr(Me)2,Thr4,Tyr9-NH2]-加压素（OTA）对大鼠睾丸中的OT受体进行了特性鉴定和定位。使用放射性碘化血管加压素（AVP）V1a受体拮抗剂125I标记的d(CH2)5Sar7-AVP和放射性碘化线性AVP V1a拮抗剂125I标记的[(C6H5-CH2CO)-O-甲基-D-酪氨酸-苯丙氨酸-谷氨酰胺-天冬酰胺-精氨酸-脯氨酸-精氨酸-脯氨酸-精氨酸-酪氨酸-NH2]，将受体密度和定位与大鼠睾丸精氨酸加压素（AVP）受体进行了比较。125I标记的OTA与大鼠睾丸膜部分（Ka = 13.8 +/- 1.25升/纳摩尔）、乳腺组织（Ka = 20.3 +/- 4.36升/纳摩尔）和子宫（Ka = 27.8 +/- 0.74升/纳摩尔）具有高亲和力结合。用各种OT和AVP受体激动剂及拮抗剂进行的竞争研究证实该结合是与OT受体的结合。发现睾丸中的AVP受体与肝脏中的AVP V1a受体相同。睾丸中的AVP受体密度远高于OT受体密度（109 +/- 12.3对5.2 +/- 0.79（平均值 +/- 标准误）飞摩尔/毫克蛋白质）。放射自显影定位显示，OT和AVP受体均存在于睾丸的间质间隙中，这与它们与睾丸间质细胞的结合一致。AVP受体也定位在生精小管的上皮表面和睾丸血管上。本研究首次在大鼠睾丸中发现了OT受体，其具有与乳腺和子宫OT受体相似的配体结合特性。受体定位与它们与睾丸间质细胞的结合一致。
