title: Reversible suppression of pituitary-testicular function by a sustained-release formulation of a GnRH agonist (leuprolide acetate) in dogs.
abstract: Pituitary-testicular function was studied in 15 dogs following treatment with a sustained-release formulation of a GnRH agonist, leuprolide acetate (LA). Adult male dogs were treated with a single subcutaneous injection of microencapsulated LA (0.1 or 1 mg/kg). Treatment with LA at a dose of 1 mg/kg resulted in decreased (P<0.001) ejaculatory volume and disappearance of morphologically normal spermatozoa within 8 wk and the effect persisted for 6 wk, while the 0.1 mg/kg dose was not adequate to effect suppression of spermatogenesis. The larger dose treatment (1 mg/kg) caused a transient rise in plasma levels of LH and testosterone followed by a marked decline to below the normal level by 2 wk, the low levels being maintained for at least 5 wk, indicating a prolonged effect of LA treatment on pituitary-gonadal axis. Twenty weeks after treatment with LA, a complete return to normal spermatogenesis was observed. The full reversibility of spermatogenesis in the dog after LA treatment suggests that this peptide could be used as a reversible method of male contraception.
authors.affiliation: Department of Animal Reproduction, College of Agriculture, Osaka Prefecture University, Sakai, Osaka 593, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Inaba
authors.forename: T
authors.initials: T
authors.lastname: Umehara
authors.forename: J
authors.initials: J
authors.lastname: Mori
authors.forename: R
authors.initials: R
authors.lastname: Torii
authors.forename: H
authors.initials: H
authors.lastname: Tamada
authors.forename: T
authors.initials: T
authors.lastname: Sawada