Nandrolone-induced aggressive behavior is associated with alterations in extracellular glutamate homeostasis in mice.

Nandrolone decanoate (ND), an anabolic androgenic steroid (AAS), induces an aggressive phenotype by mechanisms involving glutamate-induced N-methyl-d-aspartate receptor (NMDAr) hyperexcitability. The astrocytic glutamate transporters remove excessive glutamate surrounding the synapse. However, the impact of supraphysiological doses of ND on glutamate transporters activity remains elusive. We investigated whether ND-induced aggressive behavior is interconnected with GLT-1 activity, glutamate levels and abnormal NMDAr responses. Two-month-old untreated male mice (CF1, n=20) were tested for baseline aggressive behavior in the resident-intruder test. Another group of mice (n=188) was injected with ND (15mg/kg) or vehicle for 4, 11 and 19days (short-, mid- and long-term endpoints, respectively) and was evaluated in the resident-intruder test. Each endpoint was assessed for GLT-1 expression and glutamate uptake activity in the frontoparietal cortex and hippocampal tissues. Only the long-term ND endpoint significantly decreased the latency to first attack and increased the number of attacks, which was associated with decreased GLT-1 expression and glutamate uptake activity in both brain areas. These alterations may affect extracellular glutamate levels and receptor excitability. Resident males were assessed for hippocampal glutamate levels via microdialysis both prior to, and following, the introduction of intruders. Long-term ND mice displayed significant increases in the microdialysate glutamate levels only after exposure to intruders. A single intraperitoneal dose of the NMDAr antagonists, memantine or MK-801, shortly before the intruder test decreased aggressive behavior. In summary, long-term ND-induced aggressive behavior is associated with decreased extracellular glutamate clearance and NMDAr hyperexcitability, emphasizing the role of this receptor in mediating aggression mechanisms.

Aclimatação em altitude simulada: efeitos sobre a frequência cardíaca e saturação de oxigênio da hemoglobina em jogadores de futebol / Acclimatization at simulated altitude: effects on the heart rate and hemoglobin oxygen saturation in soccer players

A exposição aguda à altitude sem aclimatação prévia pode provocar mal-estar e diminuir o desempenho físico e esportivo. O objetivo deste estudo foi verificar o efeito de sessões de hipoxia normobárica, em repouso, na Frequência Cardíaca (FC) e Saturação de Oxigênio da Hemoglobina (SpO2) em atletas de futebol profissional. Participaram do estudo 13 atletas, os quais foram submetidos a 15 sessões de hipoxia, 5-6 vezes por semana. A duração das sessões foi de 60 min, com fração inspirada de oxigênio entre 14% e 12 %. A SpO2 e FC foram registrados segundo a segundo durante a primeira e última sessão. Para comparar, a SpO2 e FC da primeira sessão, última sessão e normoxia foi utilizado Anova para medidas repetidas. Houve aumento da SpO2 (p<0,05) e redução da FC (p<0,05) na última sessão, quando comparado à primeira. Concluímos que o protocolo de treinamento utilizado no estudo melhora a resposta do organismo em hipoxia.

The acute exposure at altitude without previous acclimatization may cause sickness and decrease the sport and physical performance. This research aimed at verifying the effect of normobaric hypoxia sessions, at rest, on the Hemoglobin Oxygen Saturation (SpO2) and the Heart Rate (HR) of professional soccer athletes. Thirteen athletes performed 15 sessions of hypoxia, 5-6 times a week, with 60 min of duration and with the fraction of inspired oxygen between 14 and 12%. The SpO2 and HR were recorded every second during the first and the last session. In order to compare the SpO2 and HR from the first session, last session and normoxia it was used the ANOVA with repeated measures. There was an increase in the SpO2 (p<0.05) and a decreased HR (p<0.05) for the last session when compared to the first session. We conclude that the training protocol used in the acclimatization study improves the organism response to hypoxia.