Orexin receptors: a journey through their discovery to the development of suvorexant, the new sleeping pill

Orexin (OX) neuropeptides acting through G-protein coupled OX1 and OX2 receptors are implicated in a variety of physiological roles including regulation of feeding, sleep-wake cycle, energy metabolism and reward pathways. Accumulating experimental evidence indicates that orexins are wake promoting neuropeptides and deficits in orexinergic neurotransmission leads to narcolepsy, a debilitating sleep disorder. This has led to a search for orexin receptor agonists for pharmacotherapy of narcolepsy. However, development of orexin receptor agonists are still in their infancy stage and it invokes further research to know whether it could turn into a reality. In addition, the role of orexin neuropeptides in promoting arousal and wakefulness has generated considerable interest in developing orexin receptor antagonists for treatment of insomnia. This quest was accomplished with the approval of suvorexant by United States food and drug administration in 2014. This remarkable discovery has opened a novel approach for treatment of insomnia through neuromodulation of orexin signaling. Hence this review focuses on the orexinergic system, their physiological action and potential role as pharmacological targets

Effect of insulin on small intestinal transit in normal mice is independent of blood glucose level

BACKGROUND: Insulin is the drug of choice in the management of diabetes mellitus (DM). About 76 % of diabetic patients suffer from gastrointestinal (GI) disorders. Therapy of DM with insulin primarily involves lowering of elevated blood glucose levels. Hence, on any organ in addition to insulin's effect, hypoglycaemic effect also prevails. A systematic study exploring the effect of insulin on small intestinal transit in normal laboratory animals is lacking. Hence, in the present study, the possible effect of insulin with or without associated hypoglycaemia on small intestinal transit in normal mice was examined. RESULTS: Insulin in all the doses tested (2 μ, 2 m and 2 U/kg) elicited a significant acceleration of SIT. The lower doses of insulin (2 μ and 2 m U/kg) produced significant acceleration of SIT and were associated with normal blood glucose levels. However, the highest dose of insulin (2 U/kg) produced an acceleration of SIT that was associated with significant fall in blood glucose levels. Further, the 2 m and 2 U doses of insulin significantly elevated serum insulin and C-peptide levels. CONCLUSION: Insulin at the lowest dose produced an acceleratory effect on SIT that was independent of blood glucose and serum insulin levels in normal mice

Drugs acting on mitochondrial pathways

Mitochondrion, “the power house” of the cell plays a vital role in generating energy for the intricate functions of the cells. Mitochondria also play important roles in various apoptotic pathways. Around 80-90% of the ATP generated in cells is contributed by these organelles through the process of oxidative phosphorylation. Though this process is essential for the functioning of cells it also generates various Reactive Oxygen Species (ROS), which are toxic to cells. Hence mitochondrial dysfunction is hypothesized to be an important factor in the occurrence of disorders related to aging such as neurodegeneration and malignancies. Several commonly used drugs in clinical practice exert their action by interacting with mitochondrial pathways. This review attempts to focus on the various groups of drugs which act on mitochondria and are utilized for therapy of conditions like cancer, diabetes mellitus, neurodegeneration and so on

Clinical trials in India: Where do we stand globally?

Aims: To evaluate the trend of clinical trials in India over the last 4 years compared to the well-established countries using clinical trial registries since the advent of clinical trial registry of India (CTRI). Materials and Methods: The data of clinical trials registered in India, United States (US), and European Union (EU) were obtained from websites of CTRI, clinicaltrial.gov and EU clinical trial registry, respectively from July 20, 2007 to August 29, 2011 for a period of 4 years. Trials registered in Australia, Canada, China, and Japan were obtained from WHO′s international clinical trial registry platform for the same period. We used search words for the common diseases such as diabetes, hypertension, etc., Results: The total number of clinical trials registered during the study period was 67,448 across seven study nations. Clinical trials from India constituted only 2.7% of the total number of trials carried out, compared to US constituting 47% of the total number of trials registered, followed by 18% from EU and 11% from Japan. However, India, China, and Japan have been found to show an increase of 3.7%, 5.1%, and 13.1% increase in the number of trials registered in 2011 compared to 2007. In contrast, US and EU showed a decline of 11.3% and 11.95% respectively in the total number of trials registered in 2011 compared to 2007. Conclusions: Although India shows gradual increase in trials registered since the advent of CTRI, still it continues to lag behind established countries in clinical research

Role of ion channel modifiers in reversal of morphine–induced gastrointestinal inertia by prokinetic agents in mice

60-65Prokinetic drugs like mosapride, domperidone etc, are used to treat gastrointestinal delay. Though the receptor-mediated actions of these agents have been studied, involvement of ion channels in reversing morphine-induced gastrointestinal inertia by prokinetic agents has not been explored. Charcoal meal test was used to measure small intestinal transit (SIT) in adult male Swiss albino mice. Animals were given ion channel modifiers and prokinetic drugs intragastrically. Reversal of morphine-induced gastrointestinal delay by mosapride was decreased significantly by CaCl2, minoxidil and glibenclamide. Similarly, domperidone’s effect on morphine was decreased by CaCl2, nifedipine, minoxidil and glibenclamide significantly. The results reveal that ion channel modifiers counteract the prokinetic effects of mosapride or domperidone.</b

Polymorphisms of T- cell leukemia 1A gene loci are not related to the development of adjuvant letrozole-induced adverse events in breast cancer.

Letrozole, an aromatase inhibitor (AI), is the first-line adjuvant drug for treating hormone receptor-positive (HR+) breast cancer in postmenopausal women. However, harmful adverse events (AEs) and significant differences in drug response among individuals remain a significant problem in clinical application. Current evidence suggests that the observed individual variation in the treatment outcomes of AI is conferred by genetic variants. Hence, in this study, we examined the association of TCL1A gene polymorphisms with letrozole-induced AEs. The study subjects were postmenopausal HR+ breast cancer patients who were receiving adjuvant letrozole. Genomic DNA was isolated by a routine standard phenol-chloroform method. In total, 198 South Indian patients were genotyped for four single nucleotide polymorphisms (SNPs) in the TCL1A gene loci by the TaqMan allelic discrimination assay using the RT-PCR system. We used the odds ratio and 95% confidence interval to assess the genetic association. Musculoskeletal (MS) AEs and vasomotor symptoms (VMSs) are the most common side effects observed in the study cohort. Among 198 patients, 81 experienced musculoskeletal toxicity, reporting MS-AEs, 57 had VMSs, and 33 of them had both. The most frequently identified polymorphic variants in the patient series were rs11849538 (G), with an allele frequency of about 27.3%, followed by rs7158782-G (27.3%), rs7159713-G (25.8%), and rs2369049-G (22.5%). The genetic association analysis indicated no significant difference in the proportion of TCL1A gene variants between patients with and without AEs on either MS-AEs or VMSs. Though we observed high LD in all patient groups, the inferred haplotypes displayed a non-significant association with letrozole-induced specific AEs. However, the SNP functionality analysis by RegulomeDB provided a 2b rank score for rs7158782, suggesting a potential biological function. Our findings suggest that TCL1A gene polymorphisms may not play any role in the prediction of letrozole-induced AEs in South Indian HR+ breast cancer patients