Original Article Pharmacological evaluation of novel 5‑HT3 receptor antagonist, QCM‑13 (N‑cyclohexyl‑3‑ methoxyquinoxalin‑2‑carboxamide) as anti‑anxiety agent in behavioral test battery Deepali Gupta, Mahesh Radhakrishnan, Devadoss Thangaraj, Yeshwant Kurhe Department of Pharmacy, ABSTRACT Birla Institute of Objective: In the last few decades, serotonin type‑3 (5‑HT ) receptor antagonists have been identified as potential Technology and Science, 3 targets for anxiety disorders. In preclinical studies, 5‑HT antagonists have shown promising antianxiety effects. Pilani, Rajasthan, India 3 In this study, a novel 5‑HT3 receptor antagonist, QCM‑13(N‑cyclohexyl‑3‑methoxyquinoxalin‑2‑carboxamide) Address for correspondence: was evaluated for anxiolytic‑like activity in rodent behavioral test battery. Materials and Methods: Mice were Ms. Deepali Gupta, given QCM‑13 (2 and 4 mg/kg, intraperitoneally [i.p.]) or diazepam (2 mg/kg, i.p.) or vehicle and after 30 min, E‑mail: deepaligupta2010@ mice were subjected to four validated behavioral test batteries viz. elevated plus maze, hole board, light‑dark gmail.com and open field tests. Interaction study of QCM‑13 with m‑chlorophenyl piperazine (mCPP) (mCPP, a 5‑HT2A/2C receptor agonist, 1 mg/kg, i.p.) and buspirone (BUS, a partial 5‑HT1A agonist, 10 mg/kg, i.p.) were performed to assess the pharmacological mechanism of the drug. Results: QCM‑13 expressed potential anxiolytic effect with significant (P < 0.05) increase in behavioral parameters measured in aforementioned preliminary models. Besides, QCM‑13 was unable to reverse the anxiogenic effect of mCPP, but potentiated anxiolytic affect of BUS. Conclusion: The results suggest that QCM‑13 can be a potential therapeutic candidate for the management of anxiety‑like disorders and combination doses of novel 5‑HT3 receptor antagonist with standard anxiolytics may improve therapeutic efficacy. Received : 04‑09‑13 Review completed : 14‑12‑13 Accepted : 17‑05‑14 KEY WORDS: 5‑HT3 receptor antagonist, antianxiety activity, QCM‑13 erotonin is a biogenic amine biochemically derived such as anxiety, depression and other comorbid disorders causing S from the tryptophan, plays an important role as a significant personal distress, reduced “quality of life,” increased neurotransmitter in the monoaminergic pathways. Originating morbidity and mortality as well as a significant economic burden from raphe nuclei, it provides an intense and widespread on an individual.[4] innervation of corticolimbic structures such as frontal cortex, septum, amygdala and hippocampus, the central areas for Apart from serotonin reuptake inhibitors, serotonin transporters controlling mood and emotional behavior.[1‑3] Thus, disturbances and neurotransmission modulators, extensive research have proven in the activity of serotonergic system may lead to mood disorders the involvement of serotonin receptors agonists/antagonists (at the molecular level, including more or less all types of 5‑HT Access this article online receptors and their sub‑types) acting on both pre (5‑HT1B) as Quick Response Code: well as postsynaptic (5‑HT1, 5‑HT2, 5‑HT4, 5‑HT5‑7) receptors in Website: one or another form of anxiety disorder. Thus, the contribution www.jpbsonline.org of serotonin type‑3 receptor and sub‑types in the management of psychological disorders is quite significant.[3] DOI: 10.4103/0975-7406.154429 The pharmacological activity of various drugs with 5‑HT3 receptor antagonistic activity has also been evaluated for How to cite this article: Gupta D, Radhakrishnan M, Thangaraj D, Kurhe Y. Pharmacological evaluation of novel 5‑HT 3 receptor antagonist, QCM‑13 (N‑cyclohexyl‑3‑methoxyquinoxalin‑2‑carboxamide) as anti‑anxiety agent in behavioral test battery. J Pharm Bioall Sci 2015;7:103‑8. Journal of Pharmacy and Bioallied Sciences April-June 2015 Vol 7 Issue 2 103 Gupta, et al.: QCM-13 as antianxiety agent generalized anxiety disorders or comorbid anxieties, which Drugs are being commercially available for nonpsychological disorders such as antiemetics, prokinetics.[3] In example, QCM‑13 (N‑cyclohexyl‑3‑methoxyquinoxalin‑2‑carboxamide) ondansetron, a 5‑HT3 receptor antagonist, is studied for the [Figure 1] was synthesized by Medicinal Chemistry Group, management of depression and anxiety.[5,6] Though some BITSPilani, Rajasthan. The chemistry and analytical parameters contradictory results are observed for its anxiolytic activity it are given in Table 1. m‑chlorophenyl piperazine (mCPP) was has been found effective both in humans as well as in rodents. purchased from Lancaster Chemicals, (USA). Buspirone (BUS) [7‑9] was obtained from Astron Research Ltd., India as a generic gift Other 5‑HT3 antagonists such as tropisetron, granisetron, ricasetron, and zacopride have also been reported as potent sample. Diazepam (DIA) was purchased from the Medical Centre anxiolytic agents.[9‑12] Zhang et al. have reported that BITS‑Pilani. The drugs were freshly prepared in distilled water and administered intraperitoneally (i.p.) in a constant volume of DAIZAC, a selective high‑affinity 5‑HT3 receptor antagonist produces dose‑dependent anxiolytic‑like behavioral changes 10 mL/kg for mice and 1 mL/kg for rat. All the dose administrations in mouse elevated plus‑maze model.[13] In addition, several and experimentation were carried out between 10:00 and 13:00 h. high‑affinity 5‑HT3 antagonists are significantly found to exhibit antianxiety activities in preclinical models and Elevated plus maze test may be used as novel candidates for the management of anxiety disorders.[14] Furthermore, clinical studies have The elevated plus maze (EPM) model was first devised by Lister [18] revealed the anxiolytic‑like effects of various 5‑HT receptor and has been further suggested since then. It consisted of 3 a plus‑shaped apparatus with two open (16 cm × 5 cm) and antagonists. A previous study has shown that ondansetron two enclosed arms (16 cm × 5 cm × 12 cm) each with an effectively reversed the fear potentiated startle in humans. open roof, joined together with a central square platform and [15] Tropisetron, another 5‑HT antagonist revealed 3 elevated 25 cm from the floor. The apparatus was indirectly dose‑dependent efficacy in generalized anxiety disorder [16] illuminated with a ceiling‑suspended lamp (60 W) placed patients. Moreover, Freeman et al. have shown that at a height of 100 cm above the apparatus. Mice were given ondansetron treatment decreased anxiety in patients as QCM‑13 (2 and 4 mg/kg, i.p.) or DIA (2 mg/kg, i.p.) or vehicle measured by Hamilton Anxiety Rating Scale and Clinical and after 30 min, mice were individually subjected to the test. [17] Global Impressions of Severity scale. This suggests that During the test, each mouse was placed at the central platform 5‑HT3 receptor antagonists may be helpful for treatment facing the open arm. The number of entries and the time spent of anxiety disorders in humans. However, the efficacy of in open arms were recorded for 5 min and reported as percentage the existing 5‑HT3 receptor antagonists is questionable as values. After each test, the apparatus was sprayed with alcohol few reports have demonstrated the effect of 5‑HT3 receptor and wiped thoroughly to remove residual odor. antagonists is no more than that of placebo.[14] Therefore, captivating the recent knowledge from the previous research Light‑dark model done and activities quoted for various substituted and nonsubstituted carboxamide moieties, the current study was The method of Crawley and Goodwin was adopted with slight undertaken to investigate the neuropsychological activity of modifications.[19] The light‑dark (LD) model consisted of a a novel molecule, QCM‑13 with 5‑HT3 receptor antagonistic activity for the management of anxiety‑like deficits in validated behavioral rodent models of anxiety. Materials and Methods Animals Experiments on animal were conducted in adherence to the approved protocol of the Institutional Animal Ethics Committee (IAEC) of Birla Institute of Technology and Science (BITS), Pilani, India (protocol no. IAEC/RES/04/01, dated 22.04.09). Swiss Albino mice (22–27 g) and Wistar Figure 1: The structure of QCM-13 rats (200‑250 g) of either sex were purchased from Hisar Agricultural University, Haryana, India. Male and female animals Table 1: Chemistry and analytical parameters of QCM‑13 were housed in separate cages and maintained of standard Parameters Values laboratory conditions with alternating light and dark cycle of IUAC name N‑cyclohexyl‑3‑methoxyquinoxalin‑2‑carboxamide 12 h each, temperature 23 ± 2° C and humidity conditions pA2 value 7.6 62% ±5% RH in the housing for at least 1‑week before the log P value 2.91 commencement of the experiments. The animals had free access Melting point 148‑150°C to food (standard pellet chow feed) and filtered water ad libitum. QCM‑13: N‑cyclohexyl‑3‑methoxyquinoxalin‑2‑carboxamide, The animals were used only once for each experiment. IUAC: International union of pure and applied chemistry 104 Journal of Pharmacy and Bioallied Sciences April-June 2015 Vol 7 Issue 2 Gupta, et al.: QCM-13 as antianxiety agent polypropylene chamber (44 cm × 21 cm × 21 cm) in which Statistical analysis two‑third of the light chamber was separated from one‑third dark chamber by a 13 cm long block having 5 cm high openings. All the results are expressed as mean ± standard error of the The light chamber of the apparatus was illuminated with a mean. The data from the single drug treatment studies were 60 W bulb. Mice were given QCM‑13 (2 and 4 mg/kg, i.p.) subjected to one‑way ANOVA followed by post‑hoc Dunnet’s or DIA (2 mg/kg, i.p.) or vehicle and after 30 min, mice were test. The behavioral scores from interaction studies were individually subjected to the test. During the test, each mouse analyzed using one‑way ANOVA followed by Bonferroni’s was placed in light chamber facing toward the bulb. The animal multiple comparison test. All the comparisons were made was keenly observed for latency of the first entry into dark against the control (vehicle treatment), or as otherwise chamber when kept initially in light chamber, number of entries specified.