TMEM16 proteins: Ca2+­activated chloride channels and phospholipid scramblases as potential drug targets (Review).

TMEM16 proteins, which function as Ca2+­activated Cl­ channels are involved in regulating a wide variety of cellular pathways and functions. The modulators of Cl­ channels can be used for the molecule­based treatment of respiratory diseases, cystic fibrosis, tumors, cancer, osteoporosis and coronavirus disease 2019. The TMEM16 proteins link Ca2+ signaling, cellular electrical activity and lipid transport. Thus, deciphering these complex regulatory mechanisms may enable a more comprehensive understanding of the physiological functions of the TMEM16 proteins and assist in ascertaining the applicability of these proteins as potential pharmacological targets for the treatment of a range of diseases. The present review examined the structures, functions and characteristics of the different types of TMEM16 proteins, their association with the pathogenesis of various diseases and the applicability of TMEM16 modulator­based treatment methods.

Evaluation of HPV infection and presence of licensed HPV vaccine genotypes among genital warts in Foshan, China.

Objective: This study aimed to evaluate the prevalence of human papillomavirus (HPV) infection and presence of licensed HPV vaccine genotypes among patients with genital warts in Foshan, China from 2015 to 2022, to provide useful references for the detection, prevention and control of genital warts in Foshan. Methods: The present study retrospectively analyzed the HPV detection rates in patients with genital warts. A total of 1,625 patients were seen at the Second People's Hospital of Foshan, Guangdong Province, China, from 2015 to 2022. Samples were collected from various lesions and genotyped for 21 genotypes of HPV by infusion hybridization. The classification principle of HPV genotypes in this study: (1) Based on the relationship between HPV and carcinogenicity; (2) Based on the number of HPV genotypes infected; (3) Based on the HPV genotypes of licensed HPV vaccines. Results: The detection rate of any HPV in patients with genital warts was 80.37% (1,306/1,625). The detection rates of HPV for low-risk infection, co-infection and high-risk infection were 49.48% (804/1,625), 24.92% (405/1,625) and 5.97% (97/1,625), respectively. Single infection was the predominant type (51.94%, 844/1625). HPV-6 and HPV-11 were the predominant types of single infection; HPV-6 and HPV-52 were the predominant types of paired combinations of multiple infection. 82.22% (1,336/1,625) of the cases had an age distribution of ≤ 24, 25-34, and 35-44. The distribution of some HPV genotypes had age specificity, annual specificity and gender specificity. The genotype detection rates of 2v, 4v and 9v showed a decreasing trend with ages (all P < 0.05). The genotype detection rates of 4v and 9v showed a decreasing trend over the 8-year period (both P < 0.05). The genotype detection rates of 4v and 9v in the male group were higher than those in the female group (both P < 0.05). The genotype detection rate of 9v was significantly higher than that of 2v and 4v in the female group (both P < 0.05). Conclusion: Our study demonstrated that low-risk infection and single infection were the main types of HPV infection in patients with genital warts, mainly among young patients. Our study provides epidemiological data for the detection, prevention and control of genital warts in China.

[Advances in the Treatment of Osteochondral Lesions of the Talus]. / è·éª¨éª¨è½¯éª¨æŸä¼¤æ²»ç–—çš„ç ”ç©¶è¿›å±•.

Osteochondral lesion of the talus (OLT) is a localized cartilage and subchondral bone injury of the talus trochlea. OLT is caused by trauma and other reasons, including osteochondritis dissecans of the talus (OCD) and talus osteochondral tangential fracture. OLT can develop from being asymptomatic to subchondral bone cysts accompanied by deep ankle pain. OLT tends to occur on the medial and lateral sides of the talar vault. OLT seriously affects the patients' life and work and may even lead to disability. Herein, we reviewed advances in the treatment of OLT and the strengths and weaknesses of various treatments. Different treatment methods, including conservative treatments and surgical treatments, can be adopted according to the different subtypes or clinical symptoms of OLT. Conservative treatments mostly relieve symptoms in the short term and only slow down the disease. In recent years, it has been discovered that platelet-rich plasma injection, microfracture, periosteal bone grafting, talar cartilage transplantation, allograft bone transplantation, reverse drilling under robotic navigation, and other methods can achieve considerable benefits when each of these treatment methods is applied. Furthermore, microfracture combined with platelet-rich plasma injections, microfracture combined with cartilage transplantation, and various other treatment methods combined with anterior talofibular ligament repair have all led to good treatment outcomes.

Sevoflurane suppresses colorectal cancer malignancy by modulating ß-catenin ubiquitination degradation via circSKA3.

BACKGROUND: Sevoflurane (SEV), a commonly used inhalational anesthetic, reportedly inhibits colorectal cancer (CRC) malignancy, but whether SEV can inhibit the malignancy of CRC by regulating circular RNAs (circRNAs) remains unclear. Therefore, we aimed to identify specific circRNAs that may be affected by SEV and to investigate their functional roles in CRC. METHODS: RT-qPCR was employed to detect the expression of circRNAs and mRNAs in CRC cells and tissues. Fluorescence in situ hybridization (FISH) was used to determine the location of circSKA3. Protein expression was assessed by western blot analysis. Function-based in vitro and in vivo experiments, including CCK-8, colony formation, transwell, and apoptosis assays and mouse xenograft tumor models, were conducted using circSKA3-knockdown and circSKA3-overexpression cell lines. RNA immunoprecipitation, RNA pull-down and mass spectrometry analyses were performed to explore the related mechanism. RESULTS: Our findings revealed that SEV could inhibit CRC cell activity, proliferation and migration and promote apoptosis in CRC cells. We found that circSKA3 was upregulated in CRC and associated with poorer survival and that its expression could be reduced by SEV. The overexpression of circSKA3 reversed the effects of SEV on inhibiting cell activity, proliferation and migration and promoting apoptosis. The mechanistic analysis revealed that circSKA3 could bind to the ARM structural domain of ß-catenin and thereby disrupt its interaction with the CK1/GSK3ß/ß-TrCP1 destruction complex, resulting in the ubiquitinated degradation of ß-catenin and the activation of Wnt/ß-catenin signaling. In addition, SEV downregulated circSKA3 in vivo to inhibit tumor growth. CONCLUSIONS: All the results showed that SEV could inhibit CRC progression via circSKA3 by increasing ß-catenin ubiquitination degradation.

Long Non-coding RNA EBLN3P Regulates UHMK1 Expression by Sponging miR-323a-3p and Promotes Colorectal Cancer Progression.

Background: Growing studies have demonstrated that long non-coding RNA (lncRNA) can act as crucial roles during the progression of various tumors, including colorectal carcinoma (CRC). We aimed to determine lncRNA endogenous bornavirus-like nucleoprotein (EBLN3P) expression in CRC and examine its influence on tumor behaviors of CRC cells. Materials and Methods: Quantitative real-time polymerase chain reaction was used to determine the expression levels of EBLN3P and miR-323a-3p in CRC tissues and cell lines. Cell viability, migration, invasion, and apoptosis were assessed by Cell Counting Kit 8, colony formation, Transwell assay, wound healing assays, and flow cytometry. Bioinformatics and dual-luciferase assays were used to investigate the interaction between EBLN3P and miR-323a-3p, as well as between miR-323a-3p and U2AF homology motif kinase 1 (UHMK1). Western blot was applied for detecting the expressions of the related proteins. Results: EBLN3P was highly expressed in CRC, and its high expression was distinctly associated with increased tumor size, histology/differentiation and advanced TNM stage, and poor clinical outcome of CRC patients. EBLN3P silencing significantly inhibited the proliferation and metastasis and induced the apoptosis of CRC cells. Mechanistically, overexpression of EBLN3P exhibited tumorigenic effects through downregulating the inhibitory effects of miR-323a-3p on UHMK1 expression. The correlation analysis confirmed the positive or negative association among EBLN3P, miR-323a-3p, and UHMK1. Conclusion: EBLN3P promoted the development of CRC via targeting miR-323a-3p/UHMK1, which provided a new idea for treating CRC.

Regulation of CRMP2 by Cdk5 and GSK-3ß participates in sevoflurane-induced dendritic development abnormalities and cognitive dysfunction in developing rats.

BACKGROUND: General anesthetics such as sevoflurane interfere with dendritic development and synaptogenesis, resulting in cognitive impairment. The collapsin response mediator protein2 (CRMP2) plays important roles in dendritic development and synaptic plasticity and its phosphorylation is regulated by cycline dependent kinase-5 (Cdk5) and glycogen synthase kinase-3ß (GSK-3ß). Here we investigated whether Cdk5/CRMP2 or GSK-3ß/CRMP2 pathway is involved in sevoflurane-induced developmental neurotoxicity. METHODS: Rats at postnatal day 7 (PND7) were i.p. injected with Cdk5 inhibitor roscovitine, GSK-3ß inhibitor SB415286 or saline 20 min. before exposure to 2.8% sevoflurane for 4 h. Western-blotting was applied to measure the expression of Cdk5/CRMP2 and GSK-3ß/CRMP2 pathway proteins in the hippocampus 6 h after the sevoflurane exposure. When rats grew to adolescence (from PND25), they were tested for open-field and contextual fear conditioning, and then long term potentiation (LTP) from hippocampal slices was recorded, and morphology of pyramidal neuron was examined by Golgi staining and synaptic plasticity-related proteins expression in hippocampus were measured by western-blotting. In another batch of experiment, siRNA-CRMP2 or vehicle control was injected into hippocampus on PND5. RESULTS: Sevoflurane activated Cdk5/CRMP2 and GSK-3ß/CRMP2 pathways in the hippocampus of neonatal rats, reduced dendritic length, branches and the density of dendritic spine in pyramidal neurons. It also reduced the expressions of PSD-95, drebrin and synaptophysin in hippocampus, impaired memory ability of rats and inhibited LTP in hippocampal slices. All the impairment effects by sevoflurane were attenuated by pretreatment with inhibitor of Cdk5 or GSK-3ß. Furthermore, rat transfected with siRNA-CRMP2 eliminated the neuroprotective effects of Cdk5 or GSK-3ß blocker in neurobehavioral and LTP tests. CONCLUSION: Cdk5/CRMP2 and GSK-3ß/CRMP2 pathways participate in sevoflurane-induced dendritic development abnormalities and cognitive dysfunction in developing rats.

Inhibition of RhoA Activity Does Not Rescue Synaptic Development Abnormalities and Long-Term Cognitive Impairment After Sevoflurane Exposure.

General anesthetics interfere with dendritic development and synaptogenesis, resulting in cognitive impairment in the developing animals. RhoA signal pathway plays important roles in dendritic development by regulating cytoskeleton protein such as tubulin and actin. However, it's not clear whether RhoA pathway is involved in inhaled general anesthetics sevoflurane-induced synaptic development abnormalities and long-term cognitive dysfunction. Rats at postnatal day 7 (PND7) were injected intraperitoneally with RhoA pathway inhibitor Y27632 or saline 20 min before exposed to 2.8% sevoflurane for 4 h. The apoptosis-related proteins and RhoA/CRMP2 pathway proteins in the hippocampus were measured 6 h after sevoflurane exposure. Cognitive functions were evaluated by the open field test on PND25 rats and contextual fear conditioning test on PND32-33 rats. The dendritic morphology and density of dendritic spines in the pyramidal neurons of hippocampus were determined by Golgi staining and the synaptic plasticity-related proteins were also measured on PND33 rats. Long term potentiation (LTP) from hippocampal slices was recorded on PND34-37 rats. Sevoflurane induced caspase-3 activation, decreased the ratio of Bcl-2/Bax and increased TUNEL-positive neurons in hippocampus of PND7 rats, which were attenuated by inhibition of RhoA. However, sevoflurane had no significant effects on activity of RhoA/CRMP2 pathway. Sevoflurane disturbed dendritic morphogenesis, reduced the number of dendritic spines, decreased proteins expression of PSD-95, drebrin and synaptophysin, inhibited LTP in hippocampal slices and impaired memory ability in the adolescent rats, while inhibition of RhoA activity did not rescue the changes above induced by sevoflurane. RhoA signal pathway did not participate in sevoflurane-induced dendritic and synaptic development abnormalities and cognitive dysfunction in developing rats.

Muscone reduced the hypnotic and analgesic effect of ketamine in mice.

BACKGROUND: The aim of this study was to determine the effects of different concentrations of muscone on the ketamine requirement for hypnosis and analgesia and possible mechanism in mice. METHODS: In the hypnotic response experiment, muscone (0.5, 1.0, 2.0, 4.0, and 8.0 mg/kg) was administered 15 minutes before ketamine by intraperitoneal injection. The hypnotic response was evaluated by loss of righting reflex (LORR). In the analgesia experiment, muscone (0.5, 1.0, 2.0, and 4.0 mg/kg) was administered 15 minutes before 50 mg/kg ketamine injection. Pain threshold was assessed by measuring the tail-flick latency induced by heat radiation. Twenty minutes after ketamine injection, the mRNA expression of N-methyl-D-aspartate receptors (NR) subunits, γ-aminobutyric acid (GABA) receptors subunits, opioid receptors subunits, and some Na and Ca channels were detected by qPCR in the hippocampus of mice. RESULTS: The 50% effective dose (ED50) with 95% confidence interval of ketamine-induced LORR was 49.2 (43.4-56.4) mg/kg. About 4.0 or 8.0 mg/kg muscone increased ED50 of ketamine-induced hypnosis, which was 82.7 (70.0-98.4) mg/kg or 72.0 (65.4-85.7) mg/kg, respectively. In the analgesic experiment, ketamine alone caused an obvious analgesic effect, whereas different dose of muscone decreased pain threshold in the presence of ketamine; 4.0 mg/kg muscone up-regulated the mRNA expression of NR1 and inhibited ketamine-induced increase of δ-opioid receptor mRNA level. Muscone also inhibited Cav2.1 mRNA expression in the presence of ketamine. CONCLUSION: Muscone reduced the hypnotic and analgesic effect of ketamine in dose-independent manner in mice, which may be related to the changes of NR1 and δ-opioid receptor.

Ligustrazine Enhances the Hypnotic and Analgesic Effect of Ketamine in Mice.

The purpose of this study was to determine the effects of different concentrations of ligustrazine, an extract from Chinese herb, on ketamine requirement for hypnosis and analgesia in mice. In the hypnotic response study, mice were randomly allocated to receive saline or ligustrazine at 10, 20, 40, 80 or 160 mg·kg-1 by intraperitoneal injection. Ketamine was administrated 15 min after ligustrazine injection. The hypnotic response was determined by assessing loss of the righting reflex (LORR) after ketamine injection. The dose of ketamine was determined by modified Dixon's up-and-down method in each group. In the analgesia study, different doses of ligustrazine were administrated 15 min before 50 mg·kg-1 ketamine injection. The analgesia effects (pain threshold) were determined by heat radiation-induced tail-flick latency and evaluated before ligustrazine administration or 5, 15, 30 and 60 min after ketamine administration. The ED50 [95% confidence interval (CI)] for hypnosis induced by ketamine was 54.1 (44.8, 65.3) mg·kg-1. Ligustrazine dose-dependently decreased the ED50 for ketamine to induce hypnosis, which was [31.6 (26.2, 38.1)] mg·kg-1 with the addition of 80 mg·kg-1 ligustrazine and [27.7 (22.6, 33.7)] mg·kg-1 with the addition of 160 mg·kg-1 ligustrazine, respectively (p<0.05). Ligustrazine at 160 mg·kg-1 also increased pain threshold in the presence of ketamine. Ligustrazine enhanced the hypnotic effect of ketamine in a dose-dependent manner. Ligustrazine at a large dose also increased the analgesic effect of ketamine.

Quantification of Sulfotransferases 1A1 and 1A3/4 in Tissue Fractions and Cell Lines by Multiple Reaction Monitoring Mass Spectrometry.

BACKGROUND: Within the sulfotransferase (SULT) superfamily of metabolic enzymes, SULT1A1 and 1A3/4 isoforms are of particular interest, due to their abilities to catalyze the sulfation of phenolic endobiotics and xenobiotics. Although the difference in their substrate specificity is well documented, an isoform-specific quantification method is still not available. OBJECTIVE: To detect and quantify SULT1A1 and 1A3/4 in S9 fractions and cell lines using targeted mass spectrometry-based proteomics. METHOD: Samples were tryptically digested, and signature peptides were quantified using liquid chromatography- multiple reaction monitoring mass spectrometry (LC-MRM/MS). Stable isotopelabeled (SIL) peptides were used as internal and calibration standards. SULT1A1 and SULT1A3/4 were quantified in various S9 fractions and cell line samples. RESULTS: Intraday and interday variabilities were low for relative quantification in S9 and cell line matrices (<8%). Expression profiles were validated using Western blot analysis of S9 fractions and lentiviral transduced SULT1A-overexpressing cell lines. CONCLUSION: A reproducible method for simultaneous quantification of SULT1A1 and SULT1A3/4 in S9 fractions and cell line samples was established and validated.

Discovery of Clinical Candidate CEP-37440, a Selective Inhibitor of Focal Adhesion Kinase (FAK) and Anaplastic Lymphoma Kinase (ALK).

Analogues structurally related to anaplastic lymphoma kinase (ALK) inhibitor 1 were optimized for metabolic stability. The results from this endeavor not only led to improved metabolic stability, pharmacokinetic parameters, and in vitro activity against clinically derived resistance mutations but also led to the incorporation of activity for focal adhesion kinase (FAK). FAK activation, via amplification and/or overexpression, is characteristic of multiple invasive solid tumors and metastasis. The discovery of the clinical stage, dual FAK/ALK inhibitor 27b, including details surrounding SAR, in vitro/in vivo pharmacology, and pharmacokinetics, is reported herein.

Piperidine-3,4-diol and piperidine-3-ol derivatives of pyrrolo[2,1-f][1,2,4]triazine as inhibitors of anaplastic lymphoma kinase.

The diastereoselective synthesis and biological activity of piperidine-3,4-diol and piperidine-3-ol-derived pyrrolotriazine inhibitors of anaplastic lymphoma kinase (ALK) are described. Although piperidine-3,4-diol and piperidine-3-ol derivatives showed comparable in vitro ALK activity, the latter subset of inhibitors demonstrated improved physiochemical and pharmacokinetic properties. Furthermore, the stereochemistry of the C3 and C4 centers had a marked impact on the in vivo inhibition of ALK autophosphorylation. Thus, trans-4-aryl-piperidine-3-ols (22) were more potent than the cis diastereomers (20).

Effect of alpha-1-acid glycoprotein binding on pharmacokinetics and pharmacodynamics.

Alpha-1-acid glycoprotein (AGP, also known as AAG or orosomucoid) is an important plasma protein involved in the binding and transport of many drugs, especially basic compounds. AGP has some unique drug-binding properties that differ from those of albumin. For example, the plasma concentration of AGP is relatively low and there is only one drug-binding site in each AGP molecule. Thus, binding to AGP is saturable and displaceable. This could have potential implications for drug-drug interactions or toxicological consequences. Furthermore, AGP is an acute phase protein and the concentration of AGP in plasma can significantly increase in various diseases (such as cancer and inflammatory diseases) or following trauma (burns, surgery). Changes in AGP concentration could potentially alter the free fraction of drugs in plasma or at their target sites and eventually affect their pharmacokinetic disposition and pharmacological action. Given that an increasing number of drugs have been shown to bind preferrentially to AGP, a better understanding of this unique interaction may provide great benefit for drug discovery and development. In this review, we will focus on the effect of altered AGP binding on the pharmacokinetics and pharmacodynamics (PK/PD) of drugs, as well as the species differences in AGP binding.

Synthesis and evaluation of 4- and 5-pyridazin-3-one phenoxypropylamine analogues as histamine-3 receptor antagonists.

A novel series of 4-pyridazin-3-one and 5-pyridazin-3-one analogues were designed and synthesized as H(3)R antagonists. Structure-activity relationship revealed the 5-pyridazin-3-ones 8a and S-methyl 8b had excellent human and rat H(3)R affinities, and acceptable pharmacokinetic properties. In vivo evaluation of 8a showed potent activity in the rat dipsogenia model and robust wake-promoting activity in the rat EEG/EMG model.

A selective, orally bioavailable 1,2,4-triazolo[1,5-a]pyridine-based inhibitor of Janus kinase 2 for use in anticancer therapy: discovery of CEP-33779.

Members of the JAK family of nonreceptor tyrosine kinases play a critical role in the growth and progression of many cancers and in inflammatory diseases. JAK2 has emerged as a leading therapeutic target for oncology, providing a rationale for the development of a selective JAK2 inhibitor. A program to optimize selective JAK2 inhibitors to combat cancer while reducing the risk of immune suppression associated with JAK3 inhibition was undertaken. The structure-activity relationships and biological evaluation of a novel series of compounds based on a 1,2,4-triazolo[1,5-a]pyridine scaffold are reported. Para substitution on the aryl at the C8 position of the core was optimum for JAK2 potency (17). Substitution at the C2 nitrogen position was required for cell potency (21). Interestingly, meta substitution of C2-NH-aryl moiety provided exceptional selectivity for JAK2 over JAK3 (23). These efforts led to the discovery of CEP-33779 (29), a novel, selective, and orally bioavailable inhibitor of JAK2.

Synthesis and evaluation of a new series of 1'-cyclobutyl-6-(4-piperidyloxy)spiro[benzopyran-2,4'-piperidine] derivatives as high affinity and selective histamine-3 receptor (H3R) antagonists.

A novel class of 1'-cyclobutyl-6-(4-piperidyloxy)spiro[benzopyran-2,4'-piperidine] derivatives with low nanomolar affinity for the human and rat histamine-3 receptors (H(3)Rs) are described. The spirobenzopyran piperidine ether analogs demonstrated excellent H(3)R affinity and selectivity against histamine receptor subtypes (H(1)R, H(2)R, and H(4)R), were stable in liver microsomes, and had selectivity against CYP P450 enzymes. Compounds 10, 13, 15, and 16 demonstrated high H(3)R affinity, in vitro liver microsomal stability, selectivity against CYP isoforms, moreover, these ether analogs exhibited acceptable iv pharmacokinetic (PK) properties but had poor oral exposure in rat.

4-phenoxypiperidine pyridazin-3-one histamine H(3) receptor inverse agonists demonstrating potent and robust wake promoting activity.

Structure-activity relationships for a series of phenoxypiperidine pyridazin-3-one H(3)R antagonists/inverse agonists are disclosed. The search for compounds with improved hERG and DAT selectivity without the formation of in vivo active metabolites identified 6-[4-(1-cyclobutyl-piperidin-4-yloxy)-phenyl]-4,4-dimethyl-4,5-dihydro-2H-pyridazin-3-one 17b. Compound 17b met discovery flow criteria, demonstrated potent H(3)R functional antagonism in vivo in the rat dipsogenia model and potent wake activity in the rat EEG/EMG model at doses as low as 0.1 mg/kg ip.

Strategies to mitigate the bioactivation of 2-anilino-7-aryl-pyrrolo[2,1-f][1,2,4]triazines: identification of orally bioavailable, efficacious ALK inhibitors.

Chemical strategies to mitigate cytochrome P450-mediated bioactivation of novel 2,7-disubstituted pyrrolo[2,1-f][1,2,4]triazine ALK inhibitors are described along with synthesis and biological activity. Piperidine-derived analogues showing minimal microsomal reactive metabolite formation were discovered. Potent, selective, and metabolically stable ALK inhibitors from this class were identified, and an orally bioavailable compound (32) with antitumor efficacy in ALK-driven xenografts in mouse models was extensively characterized.

Optimization of 5-pyridazin-3-one phenoxypropylamines as potent, selective histamine H3 receptor antagonists with potent cognition enhancing activity.

Previous studies have shown that (5-{4-[3-(R)-2-methylpyrrolin-1-yl-propoxy]phenyl}-2H-pyridazin-3-one) 2 had high affinity for both the human (hH(3)R K(i) = 2.8 nM) and rat H(3)Rs (rH(3)R K(i) = 8.5 nM) but displayed low oral bioavailability in the rat. Optimization of the 5-pyridazin-3-one R(2) and R(6) positions to improve the pharmacokinetic properties over 2 led to the identification of 5-{4-[3-(R)-2-methylpyrrolidin-1-yl)propoxy]phenyl}-2-pyridin-2-yl-2H-pyridazin-3-one 29. Compound 29 displayed high affinity for both human and rat H(3)Rs (hH(3)R K(i) = 1.7 nM, rH(3)R K(i) = 3.7 nM) with a greater than 1000-fold selectivity over the other histamine receptor subtypes and favorable pharmacokinetic properties across species (F = 78% rat, 92% dog, 96% monkey). It showed low binding to human plasma proteins, weakly inhibited cytochrome P450 isoforms, and displayed an excellent safety profile for a CNS-active compound. 29 displayed potent H(3)R antagonist activity in the brain in a rat dipsogenia model and demonstrated enhancement of cognitive function in a rat social recognition model at low doses. However, the development of compound 29 was discontinued because of genotoxicity.

4,5-dihydropyridazin-3-one derivatives as histamine H3 receptor inverse agonists.

H(3)R structure-activity relationships for a new class of 4,5-dihydropyridazin-3-one H(3)R antagonists/inverse agonists are disclosed. Modification of the 4,5-dihydropyridazinone moiety to block in vivo metabolism identified 4,4-dimethyl-6-{4-[3-((R)-2-methyl-pyrrolidin-1-yl)-propoxy]-phenyl}-4,5-dihydro-2H-pyridazin-3-one 22 as a lead candidate demonstrating potent in vivo functional H(3)R antagonism in the rat dipsogenia model and robust wake promoting activity in the rat EEG/EMG model.