Efeitos de diferentes crioprotetores intracelulares no sêmen criopreservado de Prochidolus brevis (Characiformes: Prochilodontidae)

Abstract

The common curimatã (Prochidolus brevis) is a migratory fish of significant importance for commercial and subsistence fishing, which is threatened in its survival due to environmental and anthropogenic factors. Thus, seminal cryopreservation emerges as a fundamental tool for the conservation of fish gametes, utilizing them during reproductive techniques in aquaculture. This biotechnology involves the use of cryoprotective agents, which prevent the formation of intracellular ice crystals, reducing the sperm damage caused by freezing. Therefore, this research aims to evaluate the effects of different types and concentrations of intracellular cryoprotectants on the seminal cryopreservation of P. brevis, in order to enhance the existing protocols for the species. For this purpose, twentyfive sexually mature male curimatãs were hormonally induced to produce sperm using a single dosage of carp pituitary extract (CPE; 0.4 mg/kg-1 ) via intracoelomic injection. After 14 hours of induction, the animals were sedated, and semen was collected through gentle abdominal massage. The samples were initially analyzed, and those exhibiting motility higher than 80% were selected to form six pools. The treatments consisted of pools diluted in 5% glucose at a ratio of 1:9 (semen:diluent), with the addition of different concentrations of intracellular cryoprotectants: ethylene glycol (EG – 5%, 10%, and 15%), methanol (ME – 5%, 10%, and 15%), and dimethylformamide (DMF – 5%, 10%, and 15%), in addition to dimethylsulphoxide (DMSO – 10%), which was used as a control group. The samples were bottled, frozen, and subsequently stored in cryogenic containers at -196 °C. After 30 days, the samples were thawed and analyzed for the following sperm parameters: motility, morphology, DNA integrity, and plasma membrane integrity. The results showed that higher total motility rates were observed for methanol (P<0.05), regardless of the concentration used. A similar behavior was observed in morphology and membrane integrity for the methanol and DMSO treatments (P>0.05), while dimethylformamide at 5% and 15% showed the lowest sperm quality indices (P<0.05). It is concluded that, among the cryoprotectants tested, the medium with 10% methanol associated with 5% glucose is a promising alternative to the use of DMSO during the seminal cryopreservation of P. brevis.