Glutamate N-methyl-D-aspartate (NMDA) receptor activation within the dorsal column of the periaqueductal gray (dPAG) leads to antinociceptive, autonomic, and behavioral responses characterized as the fear reaction. Activation of NMDA receptors in the brain increases nitric oxide (NO) synthesis, and NO has been proposed to be a mediator of the aversive action of glutamate. This paper reviews a series of studies investigating the effects of neuronal NO synthase (nNOS) inhibition in the dPAG of mice in different aversive conditions. nNOS inhibition by infusion of Nω-propyl-L-arginine (NPLA) prevents fear-like reactions (e.g., jumping, running, freezing) induced by NMDA receptor stimulation within the dPAG and produces anti-aversive effects when injected into the same midbrain site in mice confronted with a predator. Interestingly, nNOS inhibition within the dPAG does not change anxiety-like behavior in mice exposed to the elevated plus maze (EPM), but it reverses the effect of an anxiogenic dose of NMDA injected into the same site in animals subjected to the EPM. Altogether, the results support a role for glutamate NMDA receptors and NO in the dPAG in the regulation of defensive behaviors in mice. However, dPAG nitrergic modulation of anxiety-like behavior appears to depend on the magnitude of the aversive stimulus.
O cetoconazol e o fluconazol são dois antifúngicos azólicos, de amplo espectro, utilizados no tratamento de micoses superficiais e sistêmicas. Alguns estudos relatam a embriotoxicidade e teratogenicidade induzidas por estes fármacos quando os mesmos são administrados em altas doses a ratas prenhes. O objetivo deste trabalho foi apresentar um estudo comparativo dos efeitos embriotóxicos e das anomalias esqueléticas em fetos de ratas Wistar que receberam cetoconazol e fluconazol em doses teratogênicas do 6º ao 15º dia gestacional (GD) (período da organogênese). No 21º GD as ratas foram eutanaziadas e examinadas quanto aos parâmetros padrões de performance reprodutiva. Os fetos foram corados com vermelho de alizarina e os ossos da cabeça, do tronco e dos membros anteriores e posteriores foram examinados para a verificação de anomalias esqueléticas. A freqüência de anomalias esqueléticas no grupo tratado com cetoconazol foi significante quando comparada à dos grupos fluconazol e controle.
Ketoconazole and fluconazole are two broad-spectrum azole antifungals used for the treatment of superficial and systemic mycoses. Embryotoxicity and teratogenicity have been reported in some studies when those drugs are administered at high doses to pregnant rats. The aim of this study was to present a comparative study of embryotoxic effects as well as the skeletal anomalies in fetuses of Wistar rats which received ketoconazole and fluconazole at teratogenic doses on gestational days (GD) 6 through 15 (organogenesis period). On gestational day (GD) 21, the dams were euthanized and examined for standard parameters of reproductive outcome. Fetuses were stained with alizarin red and the bones of the head, trunk, forelimb and hindlimb were examined for detection of skeletal anomalies. The frequency of skeletal anomalies in the ketoconazole-treated group was significant when compared to the fluconazole and the control group.