Neuroscience letters
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Neuroscience letters · Nov 2014
Comparative StudyDifferences in acid-induced currents between oxytocin-mRFP1 and vasopressin-eGFP neurons isolated from the supraoptic and paraventricular nuclei of transgenic rats.
The hypothalamic supraoptic nucleus (SON) and paraventricular nucleus (PVN) consists of two types of magnocellular neurosecretory cells, oxytocin (OXT) and arginine vasopressin (AVP). We generated and characterized rats that express an OXT-monomeric red fluorescent protein 1 (mRFP1) and an AVP-enhanced green fluorescent protein (eGFP) fusion transgene. These transgenic rats enable the visualization of OXT or AVP neurons. ⋯ The acid-induced currents of OXT-mRFP1 neurons were significantly smaller than those of AVP-eGFP neurons from the double transgenic rats. These currents were almost completely inhibited by amiloride. The difference of acid-sensitivity between OXT and AVP neurons might contribute to maintaining systematic order in hypothalamic function.
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Neuroscience letters · Nov 2014
Harmine mediated neuroprotection via evaluation of glutamate transporter 1 in a rat model of global cerebral ischemia.
Global cerebral ischemia (GCI) causes energy deficiency results in excessive release of glutamate from neurons. Astrocytic glutamate transporters play a predominant role in keeping extracellular glutamate concentrations below excitotoxic levels. Glutamate transporter 1 (GLT-1) may account for more than 90% of glutamate uptake in adult forebrain. ⋯ Our results showed that post-GCI administration of Harmine could attenuate cerebral infarct volume and decrease neurons death. It also caused significantly elevation of GLT-1 mRNA and protein and remarkably attenuation of astrocyte activation. We provide novel clues in understanding the mechanisms of which Harmine exerts its neuroprotective activity in neurological disorders.
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Neuroscience letters · Nov 2014
The antiallodynic effect of intrathecal tianeptine is exerted by increased serotonin and norepinephrine in the spinal dorsal horn.
The purpose of this study was to validate the effects of tianeptine on serotonergic and noradrenergic neurotransmission in a rat model of neuropathic pain. Neuropathic pain was induced by ligating the L5 and L6 spinal nerves in male Sprague-Dawley rats, and mechanical allodynia was assessed using von Frey filaments. The effects of intrathecally administered tianeptine on mechanical allodynia were assessed. ⋯ Intrathecal tianeptine significantly increased the paw withdrawal thresholds in a dose-dependent manner and the antiallodynic effect was antagonized by dihydroergocristine and yohimbine. Microdialysis studies revealed that tianeptine increased the levels of 5-HT and NE in the spinal dorsal horn. These findings suggest that tianeptine may be effective for the management of neuropathic pain and that its analgesic mechanism is exerted by increased levels of 5-HT and NE in the synaptic cleft at the spinal level.
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Neuroscience letters · Nov 2014
Piezo2 channel conductance and localization domains in Merkel cells of rat whisker hair follicles.
We have recently shown that Merkel cells transduce tactile stimuli via Piezo2 channels to initiate the sense of touch. Here we performed patch-clamp recordings to assess single channel activity on the membranes of Merkel cells in whisker hair follicles. Under the cell-attached configuration, most Merkel cell membrane patches showed large outward unitary currents with single channel conductance being ∼200pS. ⋯ While the MA current decayed rapidly, a small steady-state current component with significant channel noise could be observed. Applications of stationary and non-stationary fluctuation analyses to the MA currents yielded single channel conductance of 32.5±3.8 and 54.0±5.3pS, respectively. The lack of mechanical responses under the cell-attached configuration and the existence of Piezo2 MA currents under the whole-cell configuration raised a possibility that Piezo2 channels are preferentially located on Merkel cell processes, the membrane domains inaccessible by recording electrodes.
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Neuroscience letters · Nov 2014
Nociceptive sensitization and BDNF up-regulation in a rat model of traumatic brain injury.
Chronic pain after traumatic brain injury (TBI) is very common, but the mechanisms linking TBI to pain experienced in the periphery have not been described. In this set of studies we examined nociceptive sensitization and changes in spinal cord gene expression using the rat lateral fluid percussion model of mild TBI. ⋯ We also found that spinal cord levels of brain derived neurotrophic factor (BDNF) but not several other pain-related genes were up-regulated one week after injury. Our findings suggest that TBI-induced up-regulation of spinal BDNF levels might contribute to chronic TBI-related pain, and that the lateral fluid percussion model might be useful for exploring this relationship.