Abstract
BackgroundThe hypothalamus is an essential part of the brain that responds to a variety of signaling including stressful stimulations and acupuncture signals. It is also the key element of the hypothalamic-pituitary-adrenal cortex axis(HPAA). The effect of acupuncture is transmitted into the brain from the distance sensory receptor around the acupoints via peripheral nerves and body fluid. In vivo recording the activities of stress reaction neurons (SRNs, CRH-like neurons) in hypothalamic paraventricular nucleus (PVN) in response to the stimulations from different acupoints could therefore objectively reflect the acupuncture afferent effect.MethodsIn this study, the electrophysiological method was adopted to record synchronously the activities of 43 CRH-like neurons after acupuncture stimulations at 33 acupoints located at the different regions. The acupoints that specifically activate certain CRH-like neurons (specificity acupoints) were selected. Furthermore, we investigated in a rat model of unpredictable chronic mild stress (UCMS) whether these specificity acupoints regulate HPAA function. The endpoints of measurement include corticosterone (CORT) level in peripheral blood, the expressions of corticotrophin releasing hormone (CRH) and glucocorticoid receptor (GR) protein in PVN and the animal behavioral performance.ResultsOur results reveal that Shenshu (BL23), Ganshu (BL18), Qimen (LR14), Jingmen (GB25), Riyue (GB24), Zangmen (LR13), Dazui (DU14) and auricular concha region (ACR) are the specificity acupoints; and Gallbladder, Liver and Du Channels were the specificity Channels. The acupoints on Gallbladder Channel and the acupoints innervated by the same spinal cord segments as the adrenal gland demonstrated dramatic effects.ConclusionsThis study provides a new platform to further explore acupoints specificity in the regulation of HPAA activities.
Highlights
The hypothalamus is an essential part of the brain that responds to a variety of signaling including stressful stimulations and acupuncture signals
General features of paraventricular nucleus (PVN) neurons In this study, the spikes of 653 neurons in PVN were recorded in 172 male SD rats. 163 neurons responded to hot water stimulus at 48°C, (24.96% of the total neurons recorded); of which, 121 neurons exhibited the intensive reaction (Figure 1A, the neuron firing was in the range from 34.13 ± 4.27 to 89.08 ± 14.65 spikes/second, and the excitatory rate was 161%) and 42 neurons presented the inhibitory reaction
The results showed that the difference was significant in comparison of Shenshu (BL23), Qimen (LR14) and Ganshu (BL18) with auricular concha region (ACR), Shuigou (DU26), Fengchi (GB20), Wuyi (ST15), Dashu (BL11) and Shanzhong (RN17) (p < 0.05), and the differences were significant in comparison of Dashu (BL11) and ACR with Fengchi (GB20), Wuyi (ST15), Dashu (BL11) and Shanzhong (RN17)
Summary
The hypothalamus is an essential part of the brain that responds to a variety of signaling including stressful stimulations and acupuncture signals It is the key element of the hypothalamic-pituitary-adrenal cortex axis(HPAA). In vivo recording the activities of stress reaction neurons (SRNs, CRH-like neurons) in hypothalamic paraventricular nucleus (PVN) in response to the stimulations from different acupoints could objectively reflect the acupuncture afferent effect. The paravicellular subnucleus of PVN contains numerous neurons roducing corticotripin releasing hormone (CRH), enkephalin, or thyrotropin releasing hormone (TRH). These hormones are the principal components of stress responses through hypothalamus-hypophysis axis [1]. The estrogen increases the expression of CRH, while the androgen inhibits the activity of CRH [7,8]
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