Neuroscience letters
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Neuroscience letters · Sep 2016
Inhibition of HCN channel activity in the thalamus attenuates chronic pain in rats.
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels regulate neuronal excitability in both peripheral and central nerve systems. Emerging evidence indicates that HCN channels are involved in the development and maintenance of chronic pain. However, the impact of HCN channel activity in the thalamus on chronic pain has not been examined. ⋯ We show that ZD7288 dose-dependently attenuated mechanical allodynia and thermal hyperalgesia in rats with chronic pain. In the thalamus, immunoreactivity of both HCN1 and HCN2 subunits was increased in both rat models. These results suggest that the increased HCN channel activity in the thalamus of the ascending nociceptive pathway contributes to both chronic neuropathic and inflammatory pain conditions.
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Neuroscience letters · Sep 2016
Blockade of Cannabinoid CB1 receptor attenuates the acquisition of morphine-induced conditioned place preference along with a downregulation of ERK, CREB phosphorylation, and BDNF expression in the nucleus accumbens and hippocampus.
Cannabinoid CB1 receptor (CB1R) is highly expressed in the mesocorticolimbic system and associated with drug craving and relapse. Clinical trials suggest that CB1R antagonists may represent new therapies for drug addiction. However, the downstream signaling of CB1R is not fully elucidated. ⋯ Both morphine CPP and NO-CPP induced an upregulation of ERK, CREB phosphorylation and BDNF expression. Furthermore, pretreatment with AM251 before morphine attenuated the CPP acquisition and CB1R expression as well as the activation of ERK-CREB-BDNF cascade. Collectively, these findings demonstrate that (1) Repeated morphine with context exposures but not merely the pharmacological effects of morphine increased CB1R expression both in the NAc and hippocampus. (2) CB1R antagonist mediated blockade of ERK-CREB-BDNF signaling activation in the NAc and hippocampus may be an important mechanism underlying the attenuation of morphine CPP.