Neuroscience
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Scratching inhibits pruritogen-evoked responses of neurons in the superficial dorsal horn, implicating a spinal site for scratch inhibition of itch. We investigated if scratching differentially affects neurons depending on whether they are activated by itchy vs. painful stimuli, and if the degree of inhibition depends on the relative location of scratching. We recorded from rat lumbar dorsal horn neurons responsive to intradermal (id) microinjection of serotonin (5-hydroxytryptamine, 5-HT). ⋯ These results indicate that scratching exerts a state-dependent inhibitory effect on responses of spinal neurons to pruritic but not algesic stimuli. Moreover, on-site scratching first excited neurons followed by inhibition, while off-site scratching immediately evoked the inhibition of pruritogen-evoked activity. This accounts for the suppression of itch by scratching at a distance from the site of the itchy stimulus.
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We explored the attenuating effects of NP-9 on β-amyloid (Aβ) aggregation and amyloid-induced toxicity. NP-9 is a recently reported monoamine oxidase B (MAO-B), and acetylcholinesterase (AChE) inhibitor. In the present study, we found that NP-9 inhibited AChE activity in a dose-dependent manner with a maximal inhibition dose of 8 mg/kg, i.p. ⋯ NP-9 has shown marked protection against scopolamine and Aβ1-42-induced memory impairments. It also minimized neuronal loss and amyloid plaque deposition in the brains of Aβ1-42-induced mice model. Therefore, NP-9 could be a promising lead molecule for AD, with effects against MAO-B, AChE, Aβ aggregation, and Aβ1-42 induced toxicity.
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Increases in plasma osmolality enhance nitric oxide (NO) levels in magnocellular neurosecretory cells (MNCs) of the supraoptic nucleus (SON) and modulate the secretion of both vasopressin (VP) and oxytocin (OT). In this paper, we describe the effects of hypertonicity on the electrical properties of MNCs by focusing on the nitrergic modulation of their activity in this condition. Membrane potentials were measured using the patch clamp technique, in the presence of both glutamatergic and GABAergic neurotransmission blockers, in coronal brain slices of male Wistar rats. ⋯ L-Arginine prevented the increase in fire frequency induced by hypertonic stimulus, and L-NAME (inhibitor of nitric oxide synthase) induced an additional increase in frequency when applied together with the hypertonic solution. Moreover, L-Arginine hyperpolarizes the resting potential and decreases the peak value of the after-hyperpolarization; both effects were blocked by L-NAME and hypertonicity and/or L-NAME reduced the time constant of the rising phase of the after-depolarization. These results demonstrate that an intrinsic nitrergic system is part of the mechanisms controlling the excitability of MNCs of the SON when the internal fluid homeostasis is disturbed.
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Recombinant tissue-type plasminogen activator (rt-PA) is the mainstay of acute stroke treatment and the only approved medical therapy so far. Because of its fibrinolytic action, it is presumed to aggravate intracerebral hemorrhage (ICH). Since clinical features do not discriminate between ischemic stroke and ICH, brain imaging is strictly required before the initiation of thrombolysis. ⋯ In the 72 h observation, there was also no difference in functional outcome and hematoma volume. In our experimental study, we were not able to demonstrate that peracute rt-PA treatment in (primary) ICH has detrimental effects on hematoma expansion, hematoma volume or functional outcome. This finding needs careful consideration in future translational studies.
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Electromagnetic field (EMF) radiations emitted from mobile phones may cause structural damage to neurons. With the increased usage of mobile phones worldwide, concerns about their possible effects on the nervous system are rising. In the present study, we aimed to elucidate the possible effects of prenatal EMF exposure on the cerebellum of offspring Wistar rats. ⋯ The most prominent changes included afterhyperpolarization amplitude, spike frequency, half width and first spike latency. In conclusion, the results of the present study show that prenatal EMF exposure results in altered electrophysiological properties of Purkinje neurons. However, these changes may not be severe enough to alter the cerebellum-dependent functional tasks.