Design, Synthesis, and Biological Evaluation of Phenol Bioisosteric Analogues of 3-Hydroxymorphinan.

The neuroprotective agent 3-hydroxymorphinan (3-HM) is a well-documented and highly safe therapeutic intervention for the inflammatory-related effects of Parkinson's disease (PD). However, the bioavailability of 3-HM is very low due to the rapid first-pass metabolism of the phenolic moiety. In the present study, we sought to improve the metabolic stability and overall pharmacokinetic profile of 3-HM. Based on an iterative design process that a suitably arranged heterocycle with an NH group would serve as the metabolically stable isostere of the phenolic group, we designed and synthesized two analogues of 3-HM. Benzimidazolone compound 8 (imidazolone-morphinan) was comparable in activity to 3-HM against lipopolysaccharide (LPS)-induced inflammatory responses in microglial BV2 cells and in vivo animal experiments (MPTP-induced PD mouse model). Moreover, the in vitro study showed that imidazolone-morphinan was non-toxic to microglia, indicating its high safety. Considering the favourable and unique preclinical profiles, compound 8 was nominated as a candidate for further clinical development.

Intracerebroventricular injection of human prostatic acid phosphatase has potent neuroprotective effects against transient focal cerebral ischemia in rats.

Though the potential use of adenosine as a neuroprotective agent has long been realized, there are currently no adenosine-based therapies for the prevention or treatment of cerebral ischemia and reperfusion injury. Prostatic acid phosphatase (PAP), an enzyme that has long served as a diagnostic marker for prostate cancer, has been recently demonstrated to exhibit ecto-5'-nucleotidase activity, and dephosphorylate endogenous extracellular AMP to adenosine. We therefore tested the hypothesis that PAP has sustained and potent neuroprotective effects against cerebral ischemia in the rat model of middle cerebral artery occlusion. We found that hPAP produced significant neuroprotection against focal cerebral ischemia, as evident from significant reduction in cerebral infarction and neurological deficits. The therapeutic time window for hPAP in rat focal cerebral ischemia model was limited from 6 h before ischemia to 1.5 h after reperfusion. The present study suggested that PAP is a potential candidate for the prevention and treatment of cerebral ischemic injury, especially during perioperative period.

Autophagy activation is involved in neuroprotection induced by hyperbaric oxygen preconditioning against focal cerebral ischemia in rats.

Our previous studies have demonstrated that hyperbaric oxygen (HBO) preconditioning induces tolerance to focal cerebral ischemia. The present study aimed to investigate whether autophagy is involved in the neuroprotection elicited by HBO preconditioning in a rat model of transient focal cerebral ischemia. Twenty-four hours after the completion of HBO preconditioning (2.5 atm absolute in 100% oxygen for 60 min per day for 5 consecutive days), male Sprague-Dawley rats were subjected to focal cerebral ischemia by middle cerebral artery occlusion (MCAO) for 120 min. The neurobehavioral score and infarct volume were used to evaluate cerebral ischemic injury. An intracerebroventricular injection of the autophagy inhibitor 3-methyladenine (3-MA) or the autophagy inducer rapamycin was administered before HBO preconditioning or MCAO. We found that after reperfusion the protein expression of LC3-II and Beclin 1 and the formation of autophagosomes were increased by HBO preconditioning or ischemia, but the increase following HBO preconditioning was higher than the increase following ischemia. 3-MA suppressed the increases in LC3-II and Beclin 1 induced by HBO preconditioning and attenuated the neuroprotection of HBO preconditioning against cerebral ischemia. Furthermore, 3-MA treatment before MCAO aggravated subsequent cerebral ischemic injury. In contrast, pretreatment with rapamycin up-regulated LC3-II and Beclin 1 after reperfusion and mimicked the neuroprotective effect of HBO preconditioning. These results indicate that HBO preconditioning elevates autophagic activity, which elicits a neuroprotective effect against ischemic injury in the brain, and suggest a novel mechanism of HBO preconditioning-induced tolerance against transient focal cerebral ischemia.

Effect of electroacupuncture preconditioning on serum S100beta and NSE in patients undergoing craniocerebral tumor resection.

OBJECTIVE: To investigate the effect of electroacupuncture preconditioning on the serum level of S100 calcium-binding protein beta (S100beta) and neuron-specific enolase (NSE) in patients undergoing craniocerebral tumor operation. METHODS: A total of 32 patients, who would go through craniocerebral tumor resection under general anesthesia, were randomly assigned to two groups, 16 in each group. Patients in the electroacupuncture (EA) group received electroacupuncture on Fengfu acupoint (Du16) and Fengchi acupoint (GB20) for 30 min, 2 h before operation. The stimulus is 1-4 mA with a density wave frequency of 2/15 Hz. Patients in the control group received no pretreatment. Anesthesia was maintained with remifentanil at the dose of 4-8 mg/kg per hour, pumped intravenous drip of vecuronium at 1.0-2.0 microg/kg each hour, and discontinuous intravenous dripped with vecuronium bromide at 0.5-1 mg. The serum levels of S100beta and NSE were measured with ELISA before operation, before skin incision, after tumor removal, at the end of operation, and at 24 h after operation. RESULTS: The serum level of S100beta and NSE did not change before skin incision. The serum level of NSE increased significantly and the level of S100beta increased insignificantly after the tumor resection. The serum levels of S100beta and NSE in the EA group and the control group were 1.16+/-0.28 microg/L vs 1.47+/- 0.33 microg/L, 24.7+/-13.3 microg/L vs 31.4+/-14.1 microg/L at the end of the operation, respectively. Twenty-four h after operation, the correspondence indices were 1.18+/-0.31 microg/L vs 1.55+/-0.26 microg/L, and 25.5+/-12.4 microg/L vs 32.4+/- 11.7 microg/L. The two indices at these two time points were significantly increased than those before operation, respectively (P<0.05). At the end of the operation and 24 h post-operation, the serum levels of S100beta and NSE in the EA group were significantly lower than those in the control group (P<0.05). CONCLUSION: Electroacupuncture Fengchi and Fengfu for 30 min before craniocerbral tumor operation could decrease the serum level of S100beta and NSE, thus may have potential protective effect on brain damage, which needs to be further studied.