Effect of pentoxifylline in the testicular function and sperm production of equine submitted to scrotal heat stress

Author(s)

Yamê Fabres Robaina Sancler da Silva

• Document type: Doctoral Thesis
• Institution: Universidade Estadual Paulista (Unesp)
• Defense date: 2017-09-01
• Advisor: Frederico Ozanam Papa

Abstract

The objectives of this study are to evaluate the effect of oral treatment with pentoxifylline on seminal quality, morphometry, histology, and gene expression in the testicle of stallions thermal-induced. In addition, it aims to investigate the efficiency of a new method of scrotal heating. For this, 14 stallions were divided into three groups: Control (CT, n = 4), Degenerate (DG, n = 5) and Degenerate Treated (PTX, n = 5). The scrotal heating was induced by a thermal bag attached to an air source at 50 ° C, for an hour in the early morning and an hour in the late afternoon, on D-1 and D0. One day after the insult (D1), treatment with oral pentoxifylline (17mg/Kg) every 12 hours was initiated and carried out for 30 days. Twice-a-week semen collections were performed from D24 to D60 and semen was evaluated for kinetics, morphology, plama membrane integrity, generation of intracellular and mitochondrial superoxide ânion, lipid peroxidation index and activated caspase 3 and 7 index. In D30 and D60 testicular biopsies were carried out and the samples destined to histopathology and to RT-qPCR, regarding the response to apoptosis, heat-shock and oxidative stress. Testicular length, height and width were measured, using a caliper, and the relative testicular volume were calculated once a week from D5 to D60. Among the results obtained, the scrotal thermal stress method used was efficient in inducing testicular degeneration in stallions. Treatment with pentoxifylline showed a beneficial effect on semen in terms of total motility and percentage of rapid sperm. In addition, it minimized the lipid peroxidation, the activation of apoptosis mechanisms in sperm and caused decreased number of sperm defects (the number of sperm defects (total, major and head defects, the presence of germ cells and teratological forms). In the histological evaluation, the drug led to a reduction of heat damage in D60, as a lower presence of basal membrane undulation - reflecting less atrophy of the seminiferous tubules - however, the drug was not effective in preventing the onset of lesions such as interstitial edema, germ cell vacuolation, absence of sperm, and increased lumen of the seminiferous tubules. These effects can be related to the inhibition of apoptosis in germ cells at 30 and 60 days after thermal insult and the activation of the cellular protection mechanism in response to heat shock. However, more studies about the dose and time of the use of pentoxifylline are needed to achieve better responses in the treatment of testicular degeneration in horses. (AU)

• FAPESP's process: 14/00535-4 - Effect of treatment with pentoxifylline on testicular and sperm parameters in stallions with testicular degeneration
• Grantee: Yamê Fabres Robaina Sancler da Silva
• Support Opportunities: Scholarships in Brazil - Doctorate