(C) 2012 IBRO. Published by Elsevier Ltd. All rights reserved.”
“The midbrain periaqueductal gray (PAG) is part of the brain system involved in active defense reactions to threatening stimuli. Glutamate N-methyl-d-aspartate (NMDA) receptor activation within the dorsal column of the PAG (dPAG) leads to autonomic and behavioral responses characterized as the fear
reaction. Nitric oxide (NO) has been proposed to be a mediator of the aversive action of glutamate, since the activation of NMDA receptors in the brain increases NO synthesis.
We investigated the effects see more of intra-dPAG infusions of NMDA on defensive behaviors in mice pretreated with a neuronal nitric oxide synthase (nNOS) inhibitor [N omega-propyl-l-arginine (NPLA)], in the same midbrain site, during a confrontation with a predator in the rat exposure test (RET).
Male Swiss mice received intra-dPAG injections of NPLA (0.1 or 0.4 nmol/0.1 mu l), and 10 min later, they were infused with NMDA (0.04 nmol/0.1 mu l) into the dPAG. After 10 min, each mouse was placed in the RET.
NMDA treatment enhanced avoidance behavior from the predator and markedly increased freezing behavior. These proaversive effects of NMDA were prevented by prior injection of NPLA. Furthermore, defensive behaviors (e.g., avoidance, risk assessment, freezing) were consistently reduced
by the highest dose of NPLA alone, suggesting an intrinsic effect of nitric oxide on defensive behavior in mice exposed to the RET.
These findings suggest a potential role of glutamate NMDA receptors and NO in the dPAG AR-13324 order in the regulation of defensive behaviors in mice during a confrontation with a predator in the RET.”
of the brain-derived neurotrophic factor (BDNF) in the benefits of physical exercise on cognitive functions has been widely investigated. Flavopiridol manufacturer Different from voluntary exercise, the effects of treadmill running on memory and BDNF are still controversial. Importantly, the impact of the frequency of physical exercise on memory remains still unknown. In this study, young adult and middle-aged rats were submitted to 8 weeks of treadmill running at moderate intensity and divided into 4 groups of frequency: 0, 1, 3 and 7 days/week. Aversive and recognition memory were assessed as well as the immunocontent of proBDNF, BDNF and tyrosine kinase receptor type B (TrkB) in the hippocampus. Frequencies did not modify memory in young adult animals. The frequency of 1 day/week increased proBDNF and BDNF. All frequencies decreased TrkB immunocontent. Middle-aged animals presented memory impairment along with increased BDNF and downregulation of TrkB receptor. The frequency of 1 day/week reversed age-related recognition memory impairment, but worsened the performance in the inhibitory avoidance task. The other frequencies rescued aversive memory, but not recognition memory.