Physiology & behavior
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Physiology & behavior · May 2012
Opioidergic, GABAergic and serotonergic neurotransmission in the dorsal raphe nucleus modulates tonic immobility in guinea pigs.
Tonic immobility (TI) is an innate defensive behavior that can be elicited by physical restriction and postural inversion and is characterized by a profound and temporary state of akinesis. Our previous studies demonstrated that the stimulation of serotonin receptors in the dorsal raphe nucleus (DRN) appears to be biphasic during TI responses in guinea pigs (Cavia porcellus). Serotonin released by the DRN modulates behavioral responses and its release can occur through the action of different neurotransmitter systems, including the opioidergic and GABAergic systems. ⋯ Our results indicate that the opioidergic, GABAergic and serotonergic systems in the DRN are important for modulation of defensive behavioral responses of TI. Therefore, we suggest that opioid inhibition of GABAergic neurons results in disinhibition of serotonergic neurons and this is the mechanism by which opioids could enhance TI. Conversely, a decrease in TI could occur through the activation of GABAergic interneurons.
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Physiology & behavior · May 2012
Selective breeding for endurance running capacity affects cognitive but not motor learning in rats.
The ability to utilize oxygen has been shown to affect a wide variety of physiological factors often considered beneficial for survival. As the ability to learn can be seen as one of the core factors of survival in mammals, we studied whether selective breeding for endurance running, an indication of aerobic capacity, also has an effect on learning. ⋯ In the Rotarod (motor-learning) task, the HCR animals were overall more agile but learned at a similar rate with the LCR group as a function of training. We conclude that the intrinsic ability to utilize oxygen is associated especially with tasks requiring plasticity of the brain structures implicated in flexible cognition.
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Physiology & behavior · May 2012
Low-carbohydrate high-fat diets in combination with daily exercise in rats: effects on body weight regulation, body composition and exercise capacity.
The aim of the current investigation was to examine the effects of consuming a low-carbohydrate high-fat diet (LC-HFD) in combination with daily exercise on body weight, body composition, endocrine control of the energy balance system and exercise capacity in adolescent and mature rats. ⋯ Maintenance on the LC-HFD in combination with forced daily exercise did not impact exercise capacity (total distance and meters per minute). Additionally consumption of an extreme LC-HFD in combination with daily exercise resulted in significantly less body weight gain but increased fat mass. When combined with daily exercise this diet clearly had a negative impact on body composition, but did not affect exercise capacity.
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Physiology & behavior · May 2012
TRPM2 channel protective properties of N-acetylcysteine on cytosolic glutathione depletion dependent oxidative stress and Ca2+ influx in rat dorsal root ganglion.
N-acetylcysteine (NAC) is a thiol-containing (sulphydryl donor) antioxidant, which contributes to regeneration of glutathione (GSH) and also acts through a direct reaction with free radicals. Thiol depletion has been implicated in the neurobiology of sensory neurons and pain. We reported recently an activator role of intracellular GSH depletion on calcium influx through transient receptor potential melastatin-like 2 (TRPM2) channels in rat dorsal root ganglion (DRG). ⋯ In conclusion, we observed a modulator role of NAC on Ca(2+) influx through a TRPM2 channel in intracellular GSH depleted DRG neurons. NAC incubation before BSO exposure appears to be more protective than NAC incubation after BSO exposure. Since cytosolic thiol group depletion is a common feature of neuropathic pain, our findings are relevant to the etiology and treatment of pain neuropathology in DRG neurons.