RESUMO
Chemical communication of predation risk has evolved multiple times in fish species, with conspecific alarm substance (CAS) being the most well understood mechanism. CAS is released after epithelial damage, usually when prey fish are captured by a predator and elicits neurobehavioural adjustments in conspecifics which increase the probability of avoiding predation. As such, CAS is a partial predator stimulus, eliciting risk assessment-like and avoidance behaviours and disrupting the predation sequence. The present paper reviews the distribution and putative composition of CAS in fish and presents a model for the neural processing of these structures by the olfactory and the brain aversive systems. Applications of CAS in the behavioural neurosciences and neuropharmacology are also presented, exploiting the potential of model fish [e.g., zebrafish Danio rerio, guppies Poecilia reticulata, minnows Phoxinus phoxinus) in neurobehavioural research.
Assuntos
Comunicação Animal , Aprendizagem da Esquiva , Cyprinidae/fisiologia , Poecilia/fisiologia , Comportamento Predatório , Peixe-Zebra/fisiologia , Animais , Filogenia , OlfatoRESUMO
OBJECTIVE: To evaluate varicocele effects on conventional semen parameters: sperm DNA fragmentation, chromatin packaging, mitochondrial membrane potential (MMP) and sperm apoptosis. METHODS: A cross-sectional study was carried out with semen samples from 2,399 men of couples who attended an infertility clinic. A total of 16.3% (391/2399) of the men were diagnosed with varicocele by a urologist. RESULTS: A regression analysis revealed that the percentages of sperm with DNA fragmentation, abnormal chromatin packaging, and abnormal MMP were significantly increased in individuals with varicocele, when compared to men without varicocele. Apoptosis was not influenced by varicocele. Conventional semen parameters were significantly worse in individuals with the disease. On the other hand, in men with varicocele, Spearman's correlation demonstrated that early apoptosis and abnormal MMP showed a positive and significant correlation with sperm DNA fragmentation. CONCLUSION: Men with varicocele had worse semen parameters, including increased levels of sperm DNA fragmentation, inactive mitochondria, and abnormal chromatin packaging. These changes are possible causes of infertility in individuals with varicocele.