Pentoxifylline induces hyperactivation and acrosome reaction in spermatozoa of golden hamsters: changes in motility kinematics

Pentoxifylline (PF) is used to enhance motility of spermatozoa frominfertile human subjects. We have previously shown that 0.45 mM PF improvedcapacitation of spermatozoa and fertilization of oocytes in vitro inhamsters. The present study was carried out to assess PF- induced changesin motility kinematics of hamster spermatozoa by a computer-aided spermanalyser (CASA) and determine the timing of onset of hyperactivation (HA)and acrosome reaction (AR) in PF-treated spermatozoa. Motility kinematicswere analysed by CASA for 0-8 h in the absence or presence of 0.45 mM PF inTyrode's medium supplemented with lactate, pyruvate and polyvinyl alcohol(TLP-PVA) or in TLP-PVA with bovine serum albumin (TALP-PVA). Conventionalassessment was also made on the percentage of motility and quality ofmotility of spermatozoa; values were expressed as sperm motility index(SMI). Both in TALP-PVA and TLP-PVA, PF markedly increased SMI, especiallythe quality of motility (P < 0.02) by 2-3 h which was sustained up to 6h. The motility kinematic data of PF-treated spermatozoa in TALP-PVA showedthat average path velocity, curvilinear velocity and amplitude of lateralhead displacement significantly (P < 0.05) increased as early as 2 h,with the expected decrease in straightness (STR) and linearity (LIN).Similar changes were also observed with PF-treated spermatozoa in TLP-PVA.Moreover, the percentage of hyperactivated spermatozoa in PF-treatedsamples was significantly (P < 0.001) higher than the untreated controlat 2 h. To determine whether PF could induce AR, independent of bovineserum albumin, quantitative AR was assessed by observing the presence orabsence of acrosomal cap on viable spermatozoa. PF significantly (P <0.001) increased the percentage of AR as early as 2 h, reaching maximum at4 h both in TALP-PVA (P < 0.05) and in TLP-PVA (P < 0.001). Theseresults show that, in hamsters, PF induces early onset (by 2 h) of HA andAR and increases the proportion of spermatozoa undergoing physiologicalmaturation.