Activation of A1 and A2 noradrenergic neurons in response to running in the rat.
ABSTRACT Since running accompanied with blood lactate accumulation stimulates the release of adrenocorticotropic hormone (ACTH), running above the lactate threshold (LT) acts as stress (running stress). To examine whether A1/A2 noradrenergic neurons that project to the hypothalamus activate under running stress, c-Fos immunohistochemistry was used to compare the effects of running with or without stress response on A1/A2 noradrenergic neurons. Blood lactate and plasma ACTH concentrations significantly increased in the running stress group, but not in the running without stress response and control groups, confirming different physiological impacts between different intensity of running with or without stress. Running stress markedly increased c-Fos accumulation in the A1/A2 noradrenergic neurons. Running without stress response also induced a significant increase in c-Fos expression in the A1/A2 noradrenergic neurons, and the percentage of the increase was smaller than that of running stress. The extent of c-Fos expression in the A1/A2 noradrenergic neurons correlates with exercise intensity, signifying that this neuronal activation is running speed-dependent. We thus suggest that A1/A2 noradrenergic neurons are activated in response to not only running stress, but also to other physiological running, enhanced by non-stressful running. These findings will be helpful in studies of specific neurocircuits and in identifying their functions in response to running at different intensities.
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ABSTRACT: The brain is considered to be an organ which can be affected by conditioning or exercise, just like muscles. Exercise activates the brain and enhances several neuronal functions and may lead to several neuronal plastic changes. Neuronal c-Fos accumulation in any hypothalamic nuclei increased only with supra-LT exercise, revealing a LT-like activation pattern. In the brain stem, both supra-LT and below-LT exercise activated the VLM and NTS. In case of hippocampus, its activation was induced by under-LT exercise, which increased regional blood flow through neurovascular coupling. Thus, we found that regions of brain activation were determined differently based on exercise intensity. In the further, more research on exercise intensive is indispensable. In this paper, we reviewed: (1) Hippocampal plasticity through exercise (2) Brain region-specific differential activation patterns with exercise below and above the lactate threshold (3) Hippocampal neuronal activity induced by mild exercise below the lactate threshold: regional blood flow monitoring in the hippocampus (4) Acute mild exercise induces BDNF and short-term training causes AHN (5) Why below-LT exercise is sufficient for hippocampal plasticity (6) Hippocampal activation mechanism during exercise. In particular, based on our recent findings, our focus was directed upon exercise-induced brain activation and neurogenesis.Journal of Exercise Nutrition & Biochemistry. 03/2011; 15(1):1-10.
Article: Threshold-like pattern of neuronal activation in the hypothalamus during treadmill running: establishment of a minimum running stress (MRS) rat model.[show abstract] [hide abstract]
ABSTRACT: Despite the indication that the hypothalamo-pituitary-adrenal (HPA) axis is activated during treadmill running, there have not been any studies focusing on the relationship between exercise intensity and region-specific neural activities in hypothalamus. To address this, rats were subjected to 30 min of running, either at middle (supra-LT, 25 m min(-1)) or low speeds (sub-LT, 15 m min(-1)), and c-Fos-(+) cells were counted and compared with control rats. Significant increases in blood glucose and lactate levels, and plasma ACTH and osmolality levels were observed during supra-LT running. Only supra-LT running significantly increased c-Fos induction in various hypothalamic regions, namely, the medial preoptic area (MPO), periventricular nucleus (Pe), suprachiasmatic nucleus (SCN), supraoptic nucleus (SON), parvocellular division of the paraventricular nucleus (pPVN), anterior hypothalamic area (AH), arcuate nucleus (ARC) and posterior hypothalamic nucleus (PH). However, sub-LT caused no effect on c-Fos accumulation. This indicates that the hypothalamus responds uniquely to running in a threshold-like pattern distinct from the speed-dependent pattern previously reported for the medulla oblongata [Ohiwa et al., 2006a,b]. In addition, these results showed a physiologic basis for mild exercise useful for establishing our minimum running stress (MRS) rat model, or the running conditions that minimize the activation of the HPA axis.Neuroscience Research 09/2007; 58(4):341-8. · 2.25 Impact Factor