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Spermatogenesis and sperm maturation in aged dogs

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Author(s):
Maíra Morales Brito
Total Authors: 1
Document type: Doctoral Thesis
Press: São Paulo.
Institution: Universidade de São Paulo (USP). Faculdade de Medicina Veterinária e Zootecnia (FMVZ/SBD)
Defense date:
Examining board members:
Camila Infantosi Vannucchi; Ricardo Pimenta Bertolla; Sidney Glina; Marcilio Nichi; Fabiana Ferreira de Souza
Advisor: Camila Infantosi Vannucchi
Abstract

The study on the spermatogenesis and epididymal maturation in the canine species during senescence is necessary to further elucidate the pathological sperm features of aged dogs. The present study aims to compare between young and senile dogs the vascular, hemodynamic, biometric and echogenic features of testicular and epididymal parenchyma; the tissue expression of LH, estrogen and androgen receptors in the testis and epididymal caput, corpus and cauda; the morpho- functionality of epididymal sperm and the histo-morphological differences of testis and epididymides parenchyma. Ten young dogs within reproductive age (1 to 4 years) and eight senile dogs (over 7 years), of different breeds, weighing between 10 and 40 kg, were selected and assigned to two experimental groups: Young Group and Senile Group. Dogs were evaluated through B-mode scrotal ultrasound, testicular artery spectral Doppler and color Doppler of the testis and epididymides. After orchiectomy, the expression of androgen, LH and estrogen receptors were evaluated in testis and epididymis parenchyma through RT-PCR and immunohistochemistry. Moreover, sperm were harvested from the caput, corpus and cauda epididymides and evaluated for motility, concentration, morphology, integrity of acrosomal and plasma membranes, mitochondrial functioning and chromatin condensation. For statistical analysis, Student’s T test or Wilcoxon was performed to compare between the groups and the RT-PCR data were analyzed using proc MIXED, considering P<0.05 as significant different. The Young group showed higher testicular artery blood flow speed and lower pulsatility index, as well as higher testicular vascularization compared to the Senile Group. Senile dogs had different testicular and epididymal expression pattern of androgen, LH and alpha estrogen receptors compared to young dogs. We were not able to detect the expression of beta estrogen receptor in canine testis and epididymis. Senile dogs had significant changes in epididymal sperm concentration, percentage of sperm defects, motility pattern, damage to plasma and acrosomal membranes, mitochondrial potential and activity and sperm chromatin condensation. In conclusion, senescence alters testicular artery blood flow and vascularization of the testis, without modifying testicular and epididymal biometry and echodensity. In addition, hormonal receptors (androgen, alpha estrogen and LH) were differentially expressed in aged dogs, influencing testicular and epididymal environment and, consequently, compromising spermatogenesis and sperm maturation throughout epididymides, leading to morpho- functional changes in canine sperm. (AU)

FAPESP's process: 17/06859-4 - Study of spermatogenesis and sperm maturation in senile dogs
Grantee:Maíra Morales Brito
Support Opportunities: Scholarships in Brazil - Doctorate