Local regulation of testicular immunoreactive-arginine vasopressin and steroidogenesis by naloxone.
The effects of intratesticular injection of naloxone, a universal opioid antagonist, on testicular immunoreactive (IR)-arginine vasopressin (AVP) content and on in vitro testosterone production by Leydig cells were investigated in the mouse. Bilateral intratesticular injection of increasing doses of naloxone (0.1-10 micrograms/testis) resulted 24 h later in a dose-dependent increase in testosterone production by Leydig cells incubated for 3 h in the presence or absence of hCG (100 ng/ml). Unilateral intratesticular injection of naloxone (10 micrograms) similarly enhanced basal and hCG-stimulated testosterone production by Leydig cells, but production was not modified in Leydig cells from the contralateral vehicle-injected testis, nor was it changed when the same dose was injected subcutaneously. Unilateral intratesticular injection of 10 micrograms naloxone led to a dose-dependent increase in the hCG-responsiveness without altering the slope of the hCG dose-response curve. In vitro exposure of Leydig cells to increasing doses of naloxone (10(-9) to 10(-7) M) did not alter either basal or hCG-stimulated testosterone production. Testicular IR-AVP content declined in a dose-dependent manner in naloxone-injected testis, but remained unchanged in the contralateral vehicle-injected testis and in testis from animals that received similar doses of naloxone subcutaneously. Since AVP has been shown to locally exert a negative control on testosterone production within the testis, it might be hypothesized that the increased Leydig cell activity after local naloxone administration results from reduced intratesticular IR-AVP levels.(ABSTRACT TRUNCATED AT 250 WORDS)
Fillion
C
C
Laboratoire d'Endocrinologie et de Biologie de la Reproduction, UFR Santé Médecine Biologie Humaine, Bobigny, France.
Tahri-Joutei
A
A
Allevard
A M
AM
Bedin
M
M
Huges
J N
JN
Gharib
C
C
Pointis
G
G
D000818:Animals; D001127:Arginine Vasopressin / Q000378:metabolism*; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D007985:Leydig Cells / Q000187:drug effects / Q000378:metabolism; D008297:Male; D051379:Mice; D009270:Naloxone / Q000008:administration & dosage / Q000494:pharmacology*; D013737:Testis / Q000187:drug effects* / Q000378:metabolism; D013739:Testosterone / Q000096:biosynthesis*
D006063:Chorionic Gonadotropin; D001127:Arginine Vasopressin; D009270:Naloxone; D013739:Testosterone