Conspecific and heterospecific alarm substances induce behavioral responses in juvenile catfish Rhamdia quelen

The recognition of chemical information indicating the presence of a predator is very important for prey survival. In this study we tested antipredator behavioral response of juvenile silver catfish (Rhamdia quelen) against predator odor released by two different potential predators, Hoplias malabaricus and the snake Helicops infrataeniatus, and alarm cues and disturbance cues released by conspecifics and by non-predator species, Megaleporinus obtusidens and Astyanax lacustris. We used juvenile catfish that were naive to predators. The trials consisted of a 10-min prestimulus and a 10-min post-stimulus observation period. The behavioral response displayed by silver catfish exposed to alarm cues comprised a decrease in shelter use and an increase in locomotion, and also a longer latency period before feeding. Our results showed that juvenile silver catfish can perceive chemical cues released by predators, heterospecifics and conspecifics.(AU)

O reconhecimento das informações químicas indicando a presença de predadores é muito importante para a sobrevivência da presa. Neste estudo foi testada a resposta comportamental anti-predação de juvenis de jundiás (Rhamdia quelen) a substâncias liberadas por dois predadores potenciais, Hoplias malabaricus e a cobra Helicops infrataeniatus, e substâncias de alarme liberadas por conspecíficos e pelas espécies não predadoras Megaleporinus obtusidens e Astyanax lacustris. Foram usados juvenis de jundiá que não possuíam nenhum contato prévio com predadores. Os testes consistiram em observações de períodos de 10 minutos pré estímulo e 10 minutos pós estímulo. As respostas comportamentais apresentadas pelos jundiás expostos às substâncias de alarme consistiram em diminuição no uso do abrigo, aumento na locomoção e também um longo período de latência antes de ingerir o alimento. Os resultados demonstram que juvenis de jundiá percebem substâncias químicas liberadas por predadores, heterospecíficos e conspecíficos.(AU)

Differential behavioral outcomes of 3,4-methylenedioxymethamphetamine (MDMA-ecstasy) in anxiety-like responses in mice

Anxiolytic and anxiogenic-like behavioral outcomes have been reported for methylenedioxymethamphetamine (MDMA or ecstasy) in rodents. In the present experiment, we attempted to identify behavioral, hormonal and neurochemical outcomes of MDMA treatment to clarify its effects on anxiety-related responses in 2-month-old Balb/c male mice (25-35 g; N = 7-10 mice/group). The behavioral tests used were open field, elevated plus maze, hole board, and defensive behavior against predator odor. Moreover, we also determined striatal dopamine and dopamine turnover, and serum corticosterone levels. MDMA was injected ip at 0.2, 1.0, 5.0, 8.0, 10, or 20 mg/kg. MDMA at 10 mg/kg induced the following significant (P < 0.05) effects: a) a dose-dependent increase in the distance traveled and in the time spent moving in the open field; b) decreased exploratory activity in the hole board as measured by number of head dips and time spent in head dipping; c) increased number of open arm entries and increased time spent in open arm exploration in the elevated plus maze; d) increased time spent away from an aversive stimulus and decreased number of risk assessments in an aversive odor chamber; e) increased serum corticosterone levels, and f) increased striatal dopamine level and turnover. Taken together, these data suggest an anxiogenic-like effect of acute MDMA treatment, despite the fact that behavioral anxiety expression was impaired in some of the behavioral tests used as a consequence of the motor stimulating effects of MDMA.