Background: Diabetic retinopathy (DR) has become a worldwide concern in recent years because of the high prevalence and vision-threat. The limited therapies have been in stark contrast to its high prevalence. On top of that, almost all the treatments, like laser, are applied only at the end stage of this disease. However, with the development of network pharmacology, a traditional Chinese medicine (TCM), Compound Danshen Dripping Pill (CDDP), may bring some new insights into the early intervention of DR. Methods: The active compounds and potential targets of CDDP and DR-related targets were collected from the TCMSP, UniProt, GeneCards and OMIM databases. And protein-protein interactions (PPI) information was achieved from the STRING database. The gene enrichment analysis of GO and KEGG was carried out by "clusterPro ler" in R software. The collected data was then used to form network maps of compound-target and PPI, or visualized by the software of Cytoscape. Results: 54 compounds and 50 targets were identi ed for CDDP against DR. Among the predicted effective compounds, 29 tanshinones from Radix Salviae (Danshen) were identi ed. And the core targets might be estrogen receptor (ESR1), androgen receptor (AR), caspase-3 (CASP3), Interleukin-6 (IL6) and vascular endothelial growth factor A (VEGFA) in 50 targets. There were 266 signi cantly correlated biological processes such as steroid hormone response, oxidative stress and apoptosis enriched out. Besides, The 50 targets signi cantly participate in 97 pathways and mainly enriched in advanced glycation end products (AGE)-receptor for advanced glycation end products (RAGE), uid shear stress and atherosclerosis, apoptosis and VEGF signal pathway et al. Conclusions: The mechanisms of CDDP for treating DR may involve multi-compound, multi-target and multi-pathway synergistic effects. It may participate in the regulation of steroid hormone response, oxidative stress, apoptosis and hemodynamics in diabetic retina. Tanshinones and luteolin from Radix Salviae were probably responsible for the effectiveness of CDDP on DR.

The authors show by illustration that procedures used to validate the reliability of single-concentration high-throughput screens such as the signal window and Z′ factor do not ensure sufficient reliability in potency estimates from concentration response assays. They develop the minimum significant ratio as a statistical parameter to characterize the fold change between 2 compounds run in the same experiment that can be considered a real difference and use this parameter to characterize the reliability of the assay. They adapt methods described by Bland and Altman to develop a simple set of 2 experiments to estimate the minimum significant ratio and show that this protocol can identify assays that lack reproducibility. The methods are then extended to validate the equivalency of the same assay run by multiple laboratories. (Journal of Biomolecular Screening 2006:253-261)

Xanomeline is a novel muscarinic receptor agonist relatively devoid of parasympathomimetic side effects. Xanomeline had high affinity for muscarinic receptors and much lower affinity for a variety of other neuronal receptors in radioligand binding assays. Functional studies in cell lines transfected with the muscarinic receptor subtypes demonstrated that xanomeline had higher potency and efficacy for m1 and m4 receptors than m2, m3, and m5 receptor subtypes. Similarly, in isolated tissue studies, xanomeline had higher potency and efficacy for M1 receptors in rabbit vas deferens than at M2 receptors in guinea pig atria or M3 receptors in guinea pig bladder. Secretion of soluble amyloid precursor protein from m1 cell lines was potently stimulated by xanomeline. In vivo, xanomeline robustly stimulated phosphoinositide hydrolysis in brain, consistent with m1 agonism. Xanomeline produced modest increases in brain acetylcholine levels and did not produce bradycardia, suggesting little, if any, m2 agonist activity in vivo. Additionally, xanomeline did not induce nonselective cholinergic agonist side effects such as tremor, hypothermia and salivation. In animal behavior studies, xanomeline reduced locomotion and blocked memory deficits that were induced by a muscarinic antagonist in a passive avoidance paradigm. Xanomeline was found to be safe and reasonably well tolerated in safety studies in humans. In a placebo controlled double blind clinical trial of 6 months duration, xanomeline halted cognitive decline in patients with Alzheimer's disease. Furthermore, behavioral symptoms associated with Alzheimer's disease such as hallucinations, delusions and vocal outbursts were significantly decreased by xanomeline treatment. Additional clinical trials are under way to assess the novel therapeutic effects of xanomeline. Drug Dev. Res. 40:158–170, 1997. © 1997 Wiley‐Liss, Inc.

Allosteric potentiators amplify the sensitivity of physiologic control circuits, a mode of action that could provide therapeutic advantages. This hypothesis was tested with the dopamine D1 receptor potentiator DETQ [2-(2,6-dichlorophenyl)-1-((1S,3R)-3-(hydroxymethyl)-5-(2-hydroxypropan-2-yl)-1-methyl-3,4-dihydroisoquinolin-2(1H)-yl)ethan-1-one]. In human embryonic kidney 293 (HEK293) cells expressing the human D1 receptor, DETQ induced a 21-fold leftward shift in the cAMP response to dopamine, with a Kb of 26 nM. The maximum response to DETQ alone was ∼12% of the maximum response to dopamine, suggesting weak allosteric agonist activity. DETQ was ∼30-fold less potent at rat and mouse D1 receptors and was inactive at the human D5 receptor. To enable studies in rodents, an hD1 knock-in mouse was generated. DETQ (3–20 mg/kg orally) caused a robust (∼10-fold) increase in locomotor activity (LMA) in habituated hD1 mice but was inactive in wild-type mice. The LMA response to DETQ was blocked by the D1 antagonist SCH39166 and was dependent on endogenous dopamine. LMA reached a plateau at higher doses (30–240 mg/kg) even though free brain levels of DETQ continued to increase over the entire dose range. In contrast, the D1 agonists SKF 82958, A-77636, and dihydrexidine showed bell-shaped dose-response curves with a profound reduction in LMA at higher doses; video-tracking confirmed that the reduction in LMA caused by SKF 82958 was due to competing stereotyped behaviors. When dosed daily for 4 days, DETQ continued to elicit an increase in LMA, whereas the D1 agonist A-77636 showed complete tachyphylaxis by day 2. These results confirm that allosteric potentiators may have advantages compared with direct-acting agonists.

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