Microencapsulated rrBNGF as an alternative ovulation induction method in rabbits.

Area of Science:

• Reproductive biology and endocrinology
• Biomaterials and drug delivery systems

Background:

• Rabbits are induced ovulators requiring exogenous hormone administration for ovulation.
• Traditional methods involve intramuscular injections of gonadotropin-releasing hormone (GnRH) analogues.
• Alternative intravaginal delivery systems are being explored to simplify ovulation induction.

Purpose of the Study:

• To evaluate the efficacy of intravaginal nerve growth factor (NGF) microencapsulated with chitosan for inducing ovulation in rabbits.
• To compare the effects of NGF-chitosan administered at artificial insemination (AI) versus 30 minutes prior to AI.
• To assess pregnancy rates and prolificacy following different ovulation induction protocols.

Main Methods:

• Assessed biological activity of NGF-chitosan microcapsules in PC12 cell cultures and on semen parameters.
• Administered intravaginal NGF-chitosan (NGFch-0 and NGFch-30) or GnRH analogue (intramuscular) to nulliparous and multiparous does.
• Measured progesterone levels, ovulation rates, pregnancy rates, and prolificacy in treated groups.

Main Results:

• NGF-chitosan microcapsules were biologically active and did not negatively impact semen quality.
• In nulliparous rabbits, NGFch-30 induced ovulation and pregnancy rates comparable to GnRH.
• In multiparous rabbits, GnRH showed the highest ovulation and pregnancy rates, while NGF-chitosan treatments were less effective.

Conclusions:

• Intravaginal NGF-chitosan effectively induced ovulation in nulliparous rabbits, similar to GnRH, when administered 30 minutes before AI.
• The effectiveness of NGF-chitosan may be influenced by the female's reproductive receptivity, which appears higher in nulliparous does.
• Mechanical stimulation from catheter insertion may also contribute to or mask the ovulatory response.