Sterilization of female rats by single-injection of estrogen: proof-of-concept for a nonsurgical alternative

ABSTRACT: Reproductive sterilization via surgical gonadectomy is strongly advocated to help manage animal populations, especially domesticated pets, and to prevent reproductive diseases. The present study explored the feasibility of using a single-injection method for inducing sterility in female animals as an alternative to surgical sterilization. The idea was based upon our recent finding that repetitive daily injection of estrogen into neonatal rats disrupted hypothalamic expression of Kisspeptin, the neuropeptide that triggers and regulates pulsatile secretion of GnRH in the hypothalamus. In this study, neonatal female rats were dosed with estradiol benzoate (EB) by daily injection for 11 days or subcutaneously implanted with an EB-containing Silastic capsule designed to release EB over a 2- to 3-week period. Rats treated by either method did not exhibit estrous cyclicity, were anovulatory, and became infertile. The EB-treated rats had fewer Kisspeptin neurons in their hypothalami, but their GnRH-LH axis retained responsiveness to Kisspeptin stimulation. To simplify usage, an injectable EB carrier was developed in the forms of biodegradable microspheres or pellets with pharmacokinetics comparable to the EB-containing Silastic capsule. A single injection of EB microspheres (300 µg EB) to neonatal rats made them sterile and female beagles implanted with an EB pellet at a neonatal age had lower KISS expression in their hypothalami. No concerning health impact other than infertility was observed in animals that received EB treatment at a neonatal age. Taken together, this study shows that neonatal EB administration could be developed as a non-surgical animal sterilization method.

ORGANISM(S): Rattus norvegicus

PROVIDER: GSE221002 | GEO | 2023/06/21

REPOSITORIES: GEO