Brain research
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Opioid abuse and dependence remains prevalent despite having multiple FDA-approved medications to help maintain abstinence. Mirtazapine is an atypical antidepressant receiving attention for substance abuse pharmacotherapy, and its action includes alterations in monoaminergic transmission. As monoamines are indirectly altered by opioids, the current investigation assessed the ability of mirtazapine to ameliorate morphine-induced behaviors. ⋯ Pretreatment with mirtazapine 24h prior to the CPP test had no effect on CPP expression. In contrast, a 30min pretreatment of mirtazapine attenuated the expression of both CPP and MSn. Collectively, these results indicate that mirtazapine may help to maintain abstinence in opioid dependent patients.
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Cyclosporin A (CsA) has been demonstrated to be neuroprotective in ischemic and traumatic brain injuries by inhibiting mitochondrial permeability transition pore (mPTP) opening, thereby maintaining mitochondrial homeostasis and inhibiting pro-apoptotic protein release. The effects of CsA on early brain injury (EBI) after subarachnoid hemorrhage (SAH), however, have not been investigated. This study was designed to explore the effects of CsA on apoptotic signaling pathways and EBI after experimental SAH using four equal groups (n=36) of adult male SD rats, including the sham group, SAH+vehicle group, SAH+CsA2 group, and SAH+CsA10 group. ⋯ Treatment with high dose (10mg/kg) CsA markedly decreased expressions of Cytochrome C, AIF, and cleaved caspase-3, and inhibited apoptosis pathways. Administration of CsA following SAH significantly ameliorated EBI, including cortical apoptosis, brain edema, blood-brain barrier (BBB) impairment, and neurobehavioral deficits. These findings suggest that early administration of CsA may ameliorate EBI and provide neuroprotection in the SAH model through potential mechanisms that include blockage of mPTP opening and inhibition of apoptotic cell death pathways.
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To assess developmental characteristics of nociceptive responses induced by bee venom (BV) injection in neonatal rats, we exposed pups to intra-plantar injection of various BV concentrations given at different time points between postnatal day 1 and day 28 (P1-P28). Persistent spontaneous nociception (PSN) as well as thermal and mechanical nociceptive response was compared before and after a BV injection. There were distinct age-related changes in the baseline paw withdrawal thermal latency (PWTL) and paw withdrawal mechanical threshold (PWMT) when examined on P1, P4, P7, P14, P21, and P28. ⋯ Neonatal rats receiving intra-plantar BV injection showed a time-dependent change in nociceptive responses, including (1) a dose-related increase in PSN from P1 to P28; (2) a non-specific decrease (indistinguishable between saline and BV injection) in PWTL and PWMT up to P14 and P21, respectively; and (3) a specific decrease (in response to BV injection only) in PWTL and PWMT after P14 and P21, respectively. These findings indicate that characteristic changes in the baseline and BV-induced nociceptive response are both time-dependent and modality-specific in neonatal rats. The data reveal a critical postnatal period during which nociceptive stimulation could have a significant influence on nociceptive behavior in adult rats and suggest that preclinical models of neonatal nociception should be evaluated according to different postnatal time points.