A study of the effect of B-EP and naloxone on the function of the hypothalamo-pituitary-testicular axis of the rat.
To investigate whether endogenous opioid peptides (EOP) play an important role in intragonadal regulation of testicular function and regulation of the hypothalamic-pituitary-gonadal axis of the male rat, the authors employed two principal methods: culture of testicular Leydig cells and Sertoli cells, and in vitro perifusion of hypothalamo-pituitary Leydig cells of the adult rat. The results demonstrated that incubation of Leydig cells with B-endorphin (B-EP 10(-9) = 10(-6) mol/L) or naloxone (NAL 10(-5) = 10(-8) mol/L) manifested no significant changes of non-stimulated or hCG-stimulated testosterone secretion both in 20 and 60 day-old rats. Similar results were obtained when the cells were treated with B-EP (10(-10) = 10(-7) mol/L) for 48 h during culture. Pretreatment of incubated Leydig cells with B-EP in similar concentrations for 48 h showed no effect on the response to hCG stimulation. In addition, treatment with B-EP in vitro for 24 or 72 h manifested no effects on estradiol production by aromatization of cultured Sertoli cells. Neither NAL 10(-5) given in vitro nor NAL (5 mg/body weight) injected subcutaneously 1 h before decapitation affected LH and testosterone release from the perifused hypothalamo-pituitary Leydig cells system. These results could not support the hypothesis that B-EP is a local regulator of testicular function. The physiological significance of EOP in regulating the function of gonadal axis of adult male rat remains to be investigated further.
Zhou
Z F
ZF
Department of Endocrinology, National Research Institute for Family Planning, Beijing, China.
Xiao
B L
BL
Zhang
G Y
GY
Zhuang
L Z
LZ
D000818:Animals; D001141:Aromatase / Q000378:metabolism; D002478:Cells, Cultured; D007031:Hypothalamus / Q000502:physiology; D007985:Leydig Cells / Q000187:drug effects / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000378:metabolism; D008297:Male; D009270:Naloxone / Q000494:pharmacology*; D010477:Perfusion; D010902:Pituitary Gland / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D012708:Sertoli Cells / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D013739:Testosterone / Q000378:metabolism*; D001615:beta-Endorphin / Q000502:physiology*
D009270:Naloxone; D013739:Testosterone; D001615:beta-Endorphin; D007986:Luteinizing Hormone; D001141:Aromatase