Activation of cGMP-PKG signaling pathway contributes to neuronal hyperexcitability and hyperalgesia after in vivo prolonged compression or in vitro acute dissociation of dorsal root ganglion in rats / 生理学报

Injury or inflammation affecting sensory neurons in the dorsal root ganglia (DRG) causes hyperexcitability of DRG neurons that can lead to spinal central sensitization and neuropathic pain. Recent studies have indicated that, following chronic compression of DRG (CCD) or acute dissociation of DRG (ADD) treatment, both hyperexcitability of neurons in intact DRG and behaviorally expressed hyperalgesia are maintained by activity in cGMP-PKG signaling pathway. Here, we provide evidence supporting the idea that CCD or ADD treatment activates cGMP-PKA signaling pathway in the DRG neurons. The results showed that CCD or ADD results in increase of levels of cGMP concentration and expression of PKG-I mRNA, as well as PKG-I protein in DRG. CCD or ADD treated-DRG neurons become hyperexcitable and exhibit increased responsiveness to the activators of cGMP-PKG pathway, 8-Br-cGMP and Sp-cGMP. Hyperexcitability of the injured neurons is inhibited by cGMP-PKG pathway inhibitors, ODQ and Rp-8-pCPT-cGMPS. In vivo delivery of Rp-8-pCPT-cGMPS into the compressed ganglion within the intervertebral foramen suppresses CCD-induced thermal hyperalgesia. These findings indicate that the in vivo CCD or in vitro ADD treatment can activate the cGMP-PKG signaling pathway, and that continuing activation of cGMP-PKG pathway is required to maintain DRG neuronal hyperexcitability and/or hyperalgesia after these two dissimilar forms of injury-related stress.

Inhibitory action of berberine on glucose absorption / 药学学报

<p><b>AIM</b>To study the absorption characteristics of berberine and its influence on glucose absorption.</p><p><b>METHODS</b>Rat recirculating perfusion model was used to study berberine absorption characteristics and Caco-2 cell model was used to explore the influence of berberine on disaccharidase, using HPLC to assay the appearance of glucose to indicate enzyme activities.</p><p><b>RESULTS</b>Berberine was found to be hardly absorbed in the intestine (less than 5% in 2.5 h). However, sucrase and maltase activities were found to be inhibited by berberine, its ID50 to sucrase is 1.830 mg.L-1, and showed no dose dependent influence on maltase activity. Berberine also showed influence on glucose absorption. However, this effect is not significant.</p><p><b>CONCLUSION</b>Berberine may act as an alpha-glucosidase inhibitor, which is its main mechanism in diabetes treatment.</p>