Neuroscience
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In spite of the initial and pivotal findings that the newly identified neuropeptide S (NPS) promotes arousal associated with locomotor and anxiolytic-like effects, the mechanisms through which NPS acts to modulate sleep-waking states remain unclear. The present study was undertaken to investigate in the rat the effects of i.c.v. injection of NPS on the EEG, sleep-wake cycle, and brain c-Fos expression. ⋯ Ex-vivo Fos immunohistochemistry in the posterior hypothalamus revealed that, as compared with saline-treated rats, NPS enhanced c-Fos expression in histaminergic neurons by 76.0% in the ventral tuberomammillary nucleus (TMN) and 57.8% in the dorsal TMN, and in orexinergic neurons by 28.2% in the perifornical nucleus (PeF), 24.3% in the dorsomedial hypothalamic nucleus (DMH), and 13.7% in the lateral hypothalamic area (LH) of the posterior hypothalamus. The NPS-induced c-Fos expression in histaminergic neurons and orexinergic neurons where NPS receptor (NPSR) mRNA is highly expressed, suggests that NPS activates histaminergic and orexinergic neurons to promote W.
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Interleukin-10 (IL-10) has important anti-inflammatory effects and can be protective in inflammatory conditions, such as chronic pain and infection. Exploring factors that modulate IL-10 levels may provide insight into pathomechanisms of inflammatory conditions and may provide a method of neuroprotection during these conditions. Lipopolysaccharide (LPS) stimulation of astrocytes is a source of IL-10; hence, it is of interest to investigate factors that modulate this process. ⋯ Glutamate (1 mM) significantly increased LPS (1 μg/ml)-stimulated IL-10 release from astrocytes by 166% and significantly upregulated IL-10 mRNA levels. Glutamate synergistically signaled through metabotropic glutamate receptor subgroups and the phospholipase C signaling pathway. Spinal cord astrocytes may, therefore, play a larger anti-inflammatory role than first thought in situations where glutamate and a high concentration of Toll-like receptor 4 (TLR4) agonists are present.
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Yokukansan (YKS), a traditional Japanese medicine, is composed of seven kinds of dried herbs. It is widely prescribed in clinical situation for treating psychiatric disorders such as aggressiveness in patients with dementia. We previously demonstrated that YKS and Uncaria hook (UH), which is a constituent herb of YKS, had a partial agonistic effect to 5-HT(1A) receptors in vitro. ⋯ This in vitro result on GM was further demonstrated in the socially isolated mice. As did YKS and UH, GM ameliorated the isolation-induced increased aggressiveness and decreased sociality, and the effect was counteracted by coadministration of WAY-100635. These lines of results suggest that GM in UH is potent 5-HT(1A) receptor agonist and a candidate for pharmacological effect of YKS on aggressiveness and sociality in socially isolated mice.
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In the present study, the effect of medroxyprogesterone (MPA) is evaluated for its effect on pentylenetetrazole (PTZ) kindling model of epileptogenesis in mice followed by evaluation on kindling-induced changes in cognitive and motor functions. To explore whether the effects are mediated via progesterone receptors, a selective antagonist of progesterone (mifepristone, MIF) was also taken. Kindling was induced by once every 2 days treatment with PTZ (25 mg/kg, i.p.) for 5 weeks. ⋯ On grip strength test (GST) and spontaneous alternation behavior (SAB), a significant decline in GST and % alternation was observed in kindled mice which was reversed by pre-treatment with MPA. MIF, however, could reverse only the reduced % alternation and not grip strength (GS) in PTZ-kindled animals. The study shows that MPA has antiepileptogenic effects against development of PTZ-induced kindling in mice that may not be mediated via progesterone receptors.
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Neonatal ventral hippocampal lesions (NVHL) in rats are considered a potent developmental model of schizophrenia. After NVHL, rats appear normal during their preadolescent time, whereas in early adulthood, they develop behavioral deficits paralleling symptomatic aspects of schizophrenia, including hyperactivity, hypersensitivity to amphetamine (AMPH), prepulse and latent inhibition deficits, reduced social interactions, and spatial working and reference memory alterations. Surprisingly, the question of the consequences of NVHL on postnatal neurobehavioral development has not been addressed. ⋯ Finally, our rseults show for the first time that NVHL disabled the development of behavioral routines, suggesting dramatic procedural memory deficits. The presence of procedural memory deficits in adult rats subjected to NHVL suggests that the lesions lead to a wider range of cognitive deficits than previously shown. Interestingly, procedural or implicit memory impairments have also been reported in schizophrenic patients.