Towards a high-affinity allosteric enhancer at muscarinic M1 receptors

Extract of Danggui-Shaoyao-San ameliorates cognition deficits by regulating DHA metabolism in APP/PS1 mice

ETHNOPHARMACOLOGICAL RELEVANCE

The traditional Chinese medicine formula Danggui-Shaoyao-San (DSS) has been reported to show therapeutic effect on alleviating the symptoms of Alzheimer's disease (AD).

AIM OF THE STUDY

The present study aims to investigate the relation between DSS treatment of AD and DHA metabolism and evaluates its neuroprotective effect on cognitive in APP/PS1 mice.

MATERIAL AND METHODS

DSS (1.6, 3.2, 6.4 g/kg/day) or Aricept (3 mg/kg/day) was orally administered (i.g.) to APP/PS1 mice, and saline was orally administered to Wild-type (WT) male mice as control group. Then, the Morris water maze (MWM) test, Y-maze spontaneous alternation test, open filed test and fear conditioning test were conducted for evaluation of learning and memory abilities. The DHA content was assessed by HPLC-MS/MS. Physiological indices were determined, including triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), ROS level, activity of superoxide dismutase (SOD), glutathione (GSH), malondialdehyde (MDA), PEG2, TXB2 and LTB4. The expressions of COX-1, COX-2, cPLA2, iPLA2, 15-LOX, and were assessed by Western blot.

RESULTS

APP/PS1 mice showed serious cognitive impairment in behavioral tests. However, treatment of DSS extract significantly ameliorated the cognitive deficits of APP/PS1 mice. Biochemical measurements showed the increases in TG, TC, LDL-c and the decrease in HDL-c in APP/PS1 mice compared with WT mice, and DSS extract significantly retarded these changes. Low content of DHA, low expression of iPLA2 and 15-LOX were observed both in hippocampus and cortex of APP/PS1 mice, while DSS extract significantly restored these changes. Additionally, the abnormal activity of SOD and ROS level, the decreased levels of MDA and GSH were observed in APP/PS1 mice, while DSS extract prominently lessened these changes. Moreover, DSS extract decreased the level of PEG2, TXB2 and LTB4 and also attenuated the expression of cPLA2, COX-1 and COX-2 in hippocampus as well as cortex of APP/PS1 mice.

CONCLUSIONS

Based on these results, we suggest that DSS play a positive effective role in increasing DHA content by up-regulating iPLA2 and 15-LOX, resulting in ameliorating oxidative stress and inflammation and finally ameliorating cognition deficits in APP/PS1 mice.

Bushen‑Yizhi formula ameliorates cognition deficits and attenuates oxidative stress‑related neuronal apoptosis in scopolamine‑induced senescence in mice

Bushen‑Yizhi formula (BSYZ), a traditional Chinese medicine formula consisting of six herbs has been reported to possess a neuroprotective effect. The present study aimed to investigate the effects of BSYZ on learning and memory abilities, as well as oxidative stress and neuronal apoptosis in the hippocampus of scopolamine (SCOP)‑induced senescence in mice, in order to reveal whether BSYZ is a potential therapeutic agent for Alzheimer's disease (AD). A high‑performance liquid chromatography (HPLC) fingerprint was applied to provide a chemical profile of BSYZ. Extracts of BSYZ were orally administered to mice with SCOP‑induced memory impairment for two weeks. The learning and memory abilities were determined by the Morris water maze test. The oxidant stress‑related indices, such as activity of superoxide dismutase (SOD) and levels of glutathione (GSH) and malondialdehyde (MDA) were examined in hippocampus of SCOP‑treated mice. The cell death ratio was assessed by TUNEL staining, while apoptotic‑related proteins including Bcl‑2 and Bax were determined by immuno-fluorescent staining and western blot analysis. Caspase‑3 was determined by western blot analysis. Consequently, a chromatographic condition, which was conducted at 35˚C with a flow rate of 0.8 ml/min on the Gemini C18 column with mobile phase of acetonitrile and water‑phosphoric acid (100:0.1, v/v), was established to yield common fingerprint chromatography under 203 nm with a similarity index of 0.986 within 10 batches of BSYZ samples. BSYZ at a dose of 2.92 g/kg significantly improved the cognitive ability, restored the abnormal activity of SOD and increased the levels of MDA and GSH induced by SCOP. Moreover, the neural apoptosis in the hippocampus of SCOP‑treated mice was reversed by BSYZ by regulating the expression of Bcl‑2, Bax and caspase‑3. The results demonstrated that BSYZ had neuroprotective effects in SCOP‑induced senescence in mice by ameliorating oxidative stress and neuronal apoptosis in the brain, supporting its potential in AD treatment.

Identification of indole derivatives exclusively interfering with a G protein-independent signaling pathway of the prostaglandin D2 receptor CRTH2

The anti-inflammatory drugs indomethacin and ramatroban, the latter showing clinical efficacy in treating allergic asthma, have been shown to act as a classic agonist and antagonist, respectively, of the G protein-coupled chemoattractant receptor-homologous molecule expressed on Th2 cells (CRTH2 receptor). Here, we report the identification of two indole derivatives 1-(4-ethoxyphenyl)-5-methoxy-2-methylindole-3-carboxylic acid and N(alpha)-tosyltryptophan (hereafter referred to as 1 and 2, respectively), which are structurally related to indomethacin and ramatroban but which selectively interfere with a specific G protein-independent signaling pathway of CRTH2. In whole-cell saturation-binding assays, 1 and 2 both increase the number of [(3)H]prostaglandin D2 (PGD2)-recognizing CRTH2 sites and the affinity of PGD2 for CRTH2. Enzyme-linked immunosorbent assays show that they do not alter the total number of CRTH2 receptors on the cell surface. Analysis of their binding mode indicates that unlike indomethacin or ramatroban, 1 and 2 can occupy CRTH2 simultaneously with PGD2. On a functional level, however, 1 and 2 do not interfere with PGD2-mediated activation of heterotrimeric G proteins by CRTH2. In contrast, both compounds inhibit PGD2-mediated arrestin translocation via a G protein-independent mechanism. In human eosinophils endogenously expressing CRTH2, 1 selectively decreases the efficacy but not the potency of PGD2-induced shape change, unlike ramatroban, which displays competitive antagonistic behavior. These data show for the first time that "antagonists" can cause markedly dissimilar degrees of inhibition for different effector pathways and suggest that it may be possible to develop novel classes of specific signal-inhibiting drugs distinct from conventional antagonists.