Pharmacokinetics and tissue distribution of N-3- methoxybenzyl-palmitamide in rat: A macamide derived from Lepidium meyenii

Purpose: To study the pharmacokinetics and tissue distribution of N-3-methoxybenzyl-palmitamide (MPM) derived from Lepidium meyenii (Maca)Methods: MPM and N-benzylpalmitamide (BPM, as the internal standard, IS) were prepared by one-pot synthesis method and characterized. For the analysis of MPM in rat plasma and tissue samples, a rapid ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) method was developed and validated by optimizing sample preparation conditions and UPLC conditions. Finally, the pharmacokinetics and biodistribution of MPM after oral administration in rats were studied.Results: The lower limit of quantification (LLOQ) and limit of detection (LOD) of the UPLC-MS/MS method were 1.2 and 5.0 ng/mL, respectively. Good linear relationship of calibration curve (r > 0.9951) was achieved over the range of 5 – 5000 ng/mL. In pharmacokinetics, plasma concentration-time curve of MPM showed double peaks. The highest distribution of MPM after absorption was in the stomach, followed by lung. The absorption and eliminate rate of MPM were slow in rats. In fact, MPM displayed a lung targeting property.Conclusion: The developed UPLC-MS/MS method is suitable for plasma and tissue distribution studies of MPM in rats. The present study can provide guidance for the further development and utilization of Maca tuber.Keywords: Macamide, Maca tuber, Lepidium meyenii, Pharmacokinetics, Tissue distribution, UPLCMS/M

Autocrine S100B in Astrocytes Promotes VEGF-dependent Inflammation and Oxidative Stress, and Causes Impairment of Neuroprotection

Abstract Background: Our previous study revealed that minimal hepatic encephalopathy (MHE) is strongly associated with neuroinflammation. Nevertheless, the underlying mechanism of the induction of inflammatory response in MHE astrocytes remains unclear. Methods: In this study, we further investigated the effect and mechanism of S100B, predominant isoform expressed and released from mature astrocytes, on MHE-like neuropathology in the MHE rat model. Results: We discovered that S100B expressions and autocrine were significantly increased in MHE rats and astrocytes isolated from MHE rats. Furthermore, we found that S100B stimulates VEGF expression via the interaction between TLR2 and RAGE in an autocrine manner. S100B-facilitated VEGF autocrine expression further led to a VEGFR2 and COX-2 interaction, which in turn induced the activation of NFƙB, eventually resulting in inflammation and oxidative stress caused by MHE astrocytes. Compared to WT astrocytes, impairment of MHE astrocytes supported neuronal growth in co-culture.Conclusions: To sum up, comprehensive-understanding of the impact of S100B-overexpressed MHE astrocyte on MHE pathology may provide insights into the etiology of MHE.</jats:p

Autocrine S100B in astrocytes promotes VEGF-dependent inflammation and oxidative stress, and causes impairment of neuroprotection

Abstract Minimal hepatic encephalopathy (MHE) is strongly associated with neuroinflammation. Nevertheless, the underlying mechanism of the induction of inflammatory response in MHE astrocytes remains unclear. In this study, we further investigated the effect and mechanism of S100B, predominant isoform expressed and released from mature astrocytes, on MHE-like neuropathology in the MHE rat model. We discovered that S100B expressions and autocrine were significantly increased in MHE rats and astrocytes isolated from MHE rats. Furthermore, we found that S100B stimulates VEGF expression via the interaction between TLR2 and RAGE in an autocrine manner. S100B-facilitated VEGF autocrine expression further led to a VEGFR2 and COX-2 interaction, which in turn induced the activation of NFƙB, eventually resulting in inflammation and oxidative stress caused by MHE astrocytes. Compared to WT astrocytes, impairment of MHE astrocytes supported neuronal growth in co-culture. To sum up, comprehensive-understanding of the impact of S100B-overexpressed MHE astrocyte on MHE pathology may provide insights into the etiology of MHE.</jats:p

Thrombospondin1 Enhanced Neuronal Wnt7a and CNTF Expressions by TNFα Signaling Pathway

Abstract Background: Thrombospondin (TSP) is an astrocyte-secreted protein, well-known for its function as a modulator of synaptogenesis and neurogenesis. The mechanism underlying the effects of TSP1 on synaptic activity and formation involved in MHE pathogenesis remains unclear. Methods: The present study explored the effect of TSP1 on neurodegeneration, inflammatory response and the activation of Wnt7a/CNTF signaling in the primary rat neurons and an MHE rat model. Results: When we treated neurons with TSP1, p38MAPK phosphorylation and TNFα expression was increased significantly. Also, the exposure of TSP1 increased the expression and release of Wnt7a and CNTF, upregulated spinophilin, enhanced the interaction of Wnt7a/CNTF with spinophilin, and triggered synaptic activity through p38/TNFα signaling in PC12 cells and primary neurons. The hippocampal injection of TSP1 siRNA in mice decreased the interaction of Wnt7a/CNTF with spinophilin, while injection of Wnt7a and CNTF improved learning and memory dysfunctions. MHE brains showed decreased TSP1 expression. The overexpression of TSP1 in the hippocampus of MHE rats ameliorated the disrupted synaptogenesis, learning, and memory. Conclusions: Taken together, these results indicated that TSP1 is a potential synaptic factor related to the inflammatory response and the activation of Wnt7a/CNTF signaling in MHE pathogenesis.</jats:p