Anisodamine affects the pigmentation, mineral density, craniofacial area, and eye development in zebrafish embryos.

Anisodamine is one of the major components of the tropine alkaloid family and is widely used in the treatment of pain, motion sickness, pupil dilatation, and detoxification of organophosphorus poisoning. As a muscarinic receptor antagonist, the low toxicity and moderate drug effect of anisodamine often result in high doses for clinical use, making it important to fully investigate its toxicity. In this study, zebrafish embryos were exposed to 1.3-, 2.6-, and 5.2-mM anisodamine for 7 days to study the toxic effects of drug exposure on pigmentation, mineral density, craniofacial area, and eye development. The results showed that exposure to anisodamine at 1.3 mM resulted in cranial malformations and abnormal pigmentation in zebrafish embryos; 2.6- and 5.2-mM anisodamine resulted in significant eye development defects and reduced bone density in zebrafish embryos. The associated toxicities were correlated with functional development of neural crest cells through gene expression (col1a2, ddb1, dicer1, mab21l1, mab21l2, sox10, tyrp1b, and mitfa) in the dose of 5.2-mM exposed group. In conclusion, this study provides new evidence of the developmental toxicity of high doses of anisodamine in aqueous solutions to organisms and provides a warning for the safe use of this drug.

Small dose of L-dopa/Benserazide hydrochloride improved sepsis-induced neuroinflammation and long-term cognitive dysfunction in sepsis mice.

The prevention and treatment of sepsis associated encephalopathy (SAE) remains challenging in clinic. Besides the anti-infection treatments and goal-directed supportive treatments, no specific method is reported for the prevention and treatment of SAE. This study tried to investigate the effects and underlying mechanisms of small dose of L-dopa/Benserazide hydrochloride (L-DA) on SAE. We found that L-DA administration (i.p.) at early stage of sepsis, but not at late stage, improved learning and memory of sepsis surviving mice in Cecal ligation and perforation (CLP) model. Corresponding to the improvement of learning and memory in CLP model, L-DA administration limited neuroinflammation, improved neuroplasticity, reversed sepsis-induced decrease of hippocampal dopamine level, but had no obvious effects on the survival and body weight recovery. Further studies showed that specific inhibitors of dopamine D1 or D2 receptors both partly reduced the protective effect of L-DA on the learning and memory of lipopolysaccharides (LPS) treated mice. D1 receptor specific inhibitor significantly blocked the anti-neuroinflammation effects of L-DA in LPS treated mice, but D2 receptor inhibitor did not. All these suggest that L-DA administration could prevent and treat SAE via dopamine D1 and D2 receptors. Dopamine D1 receptor is a potential target of anti-neuroinflammation.

Activation of AMP-activated protein kinase (AMPK) aggravated postoperative cognitive dysfunction and pathogenesis in aged rats.

The upstream signal molecule modulating neuro-inflammation and synaptic changes during the pathogenesis of postoperative cognitive dysfunction (POCD) is still elusive. Here, we examined the effects and mechanisms of energy sensor AMP-activated protein kinase (AMPK) in the pathogenesis of POCD. Our data showed that surgery significantly increased the expression of p-AMPK in aged rats (p < 0.05), but not in adult rats (p > 0.05). Moreover, inhibiting AMPK activation via compound C during operation significantly improved surgery-induced impairment of the learning and memory of aged rats in water maze (p < 0.05). Further mechanism studies showed that corresponding to the impairment of learning and memory after surgery, surgery significantly increased the activation of microglia, decreased the expressions of NR2B and p-NR2B, and increased the expressions of Tau and p-Tau, which also were obviously restored by inhibiting AMPK during operation. In contrast, Inhibiting AMPK activation during operation didn't change ATP level in the hippocampus of aged rats after surgery. These data suggest that surgery induced activation of AMPK in hippocampus in an age-dependent manner. AMPK plays important roles in POCD of aged rats via multiple mechanisms, and is a possible molecular target for the prevention and treatment of POCD.

Systemic HMGB1 Neutralization Prevents Postoperative Neurocognitive Dysfunction in Aged Rats.

Postoperative neurocognitive disorders are common complications in elderly patients following surgery or critical illness. High mobility group box 1 protein (HMGB1) is rapidly released after tissue trauma and critically involved in response to sterile injury. Herein, we assessed the role of HMGB1 after liver surgery in aged rats and explored the therapeutic potential of a neutralizing anti-HMGB1 monoclonal antibody in a clinically relevant model of postoperative neurocognitive disorders. Nineteen to twenty-two months Sprague-Dawley rats were randomly assigned as: (1) control with saline; (2) surgery, a partial hepatolobectomy under sevoflurane anesthesia and analgesia, + immunoglobulin G as control antibody; (3) surgery + anti-HMGB1. A separate cohort of animals was used to detect His-tagged HMGB1 in the brain. Systemic anti-HMGB1 antibody treatment exerted neuroprotective effects preventing postoperative memory deficits and anxiety in aged rats by preventing surgery-induced reduction of phosphorylated cyclic AMP response element-binding protein in the hippocampus. Although no evident changes in the intracellular distribution of HMGB1 in hippocampal cells were noted after surgery, HMGB1 levels were elevated on day 3 in rat plasma samples. Experiments with tagged HMGB1 further revealed a critical role of systemic HMGB1 to enable an access to the brain and causing microglial activation. Overall, these data demonstrate a pivotal role for systemic HMGB1 in mediating postoperative neuroinflammation. This may have direct implications for common postoperative complications like delirium and postoperative cognitive dysfunction.