Active immunization against GnRH in ovine (Ovis aries): testicular morphometry, histopathology and endocrine responses in prepubertal ram lambs

Abstract:

The main objective of the present research was to assess the effects of an active immunization against GnRH on male reproductive function as an alternative to surgical sterilization evaluating testicular morphometry, histopathological alterations and plasma gonadotropin levels in prepubertal ram lambs. Dorper ram lambs (age= 2 months; control group, n= 5; treatment group, n=15) were immunised by using an anti-GnRH vaccine (two administrations spaced 15d) developed by linking a GnRH homologous molecule to tetanus toxoid (clostridial toxoid) with aluminum hydroxide as coadjuvant. To determine the effectiveness of the vaccination protocol, testicular morphometry was evaluated (length, width, mean volume and total volume) together with histopathological alterations in testicular tissue samples (seminiferous tubule diameters, spermatogonia per testis and sperm presence) and endocrine responses (ELISA) from blood samples (FSH, LH, testosterone and cortisol plasma levels). Morphometric parameters (testicular length, width and volume) were significantly reduced in vaccinated animals with respect to the control group (p< 0.05). The anti-GnRH vaccine generated a reduction in testicular volume of 11- fold. Tubule diameters decreased in the vaccinated group with respect to the control by a factor of ~3.5. Both tubule and intertubular volumes significantly decreased in vaccinated ram lambs (p<0.05). There was also a significant reduction of the lumen in the vaccinated animal group (p<0.05). Vaccinated animals showed significant reductions in spermatogonial numbers by a factor of ~40-fold (p<0.05). Sperm was absent in all seminiferous …

Año de publicación:

2017

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