Short duration testosterone infusions maintain male sex behavior in Syrian hamsters.
In most mammalian species, reduced androgen availability is associated with marked reductions in male sexuality; conversely, androgen replacement in castrated males restores sex behavior within a few weeks. Testosterone (T) pulse duration, amplitude, frequency, and inter-pulse interval may be as important as total amount of hormone in determining target tissue responsiveness. We remain ignorant of the number and duration of daily T pulses necessary and sufficient to sustain male mating behavior. An in-dwelling infusion system was employed to vary T-pulse frequencies and durations. Daily 4 h infusions of aqueous T (100 microg/0.064 ml) and twice daily 4 h pulses of T (each 50 microg/0.064 ml) were sufficient to maintain ejaculatory behavior of sexually experienced castrated hamsters for 11 weeks post-castration; castrated hamsters infused with vehicle ceased to display the ejaculatory pattern 3 weeks after gonadectomy. Circulating T concentrations of hormone-infused hamsters declined markedly 7 h after the termination of each infusion. These results establish that male sex behavior can be sustained with infusions of relatively low T concentrations for 4 h/day and suggests that the basal concentrations of T sustained by the gonad during inter-pulse intervals may not be necessary for maintenance of sex behavior. 4 h T infusions were sufficient to maintain penile and seminal vesicles weights, but not ventral prostate weights or flank gland dimensions; the threshold for maintaining male sex behavior is lower than that for some androgen-dependent peripheral structures. Development of effective androgen replacement regimens that sustain sex behavior in castrated animals may be useful in the design of androgen replacement therapy for hypogonadal men.
Park
Jin Ho
JH
Department of Biochemistry and Molecular Genetics, School of Medicine, University of Virginia, 1300 Jefferson Park Ave., Charlottesville, VA 22908, USA. jinhopark@virginia.edu
Paul
Matthew J
MJ
Butler
Matthew P
MP
Villa
Philip
P
Burke
Morgan
M
Kim
Dennis P
DP
Routman
David M
DM
Schoomer
Elanor E
EE
Zucker
Irving
I
D000818:Animals; D006224:Cricetinae; D004334:Drug Administration Schedule; D020249:Hormone Replacement Therapy; D007260:Infusion Pumps; D008297:Male; D008647:Mesocricetus; D009919:Orchiectomy; D009929:Organ Size / Q000187:drug effects; D010413:Penis / Q000033:anatomy & histology / Q000187:drug effects; D011467:Prostate / Q000033:anatomy & histology / Q000187:drug effects; D012669:Seminal Vesicles / Q000033:anatomy & histology / Q000187:drug effects; D012726:Sexual Behavior, Animal / Q000187:drug effects*; D013739:Testosterone / Q000008:administration & dosage / Q000494:pharmacology*; D013997:Time Factors
D013739:Testosterone