Int. J. Pharm. Sci. Rev. Res., 46(1), September - October 2017; Article No. 43, Pages: 247-250 ISSN 0976 – 044X International Journal of Pharmaceutical Sciences Review and Research Available online at www.globalresearchonline.net © Copyright protected. Unauthorised republication, reproduction, distribution, dissemination and copying of this document in whole or in part is strictly prohibited. 247 Theophine Chinwuba Akunne * , Blessing Onyinye Okonkwo, Martha Nneoma Oforkansi Department of Pharmacology and Toxicology, Faculty of Pharmaceutical Sciences, University of Nigeria, 410001 Nsukka, Enugu State, Nigeria. *Corresponding author’s E-mail: theophine.akunne@unn.edu.ng Received: 25-07-2017; Revised: 28-08-2017; Accepted: 18-09-2017. ABSTRACT In Nigerian ethnomedicine, the root bark of Voacanga africana Stapf. (Apocynaceae) is used in the treatment of depression associated with mental and psychiatric disorders. According to World Health Organization (WHO) recent global estimates, over 300 million people are estimated to be suffering from depression. Therefore, this study was designed to evaluate the antidepressant effect of the root bark extract of V. africana using murine models, in order to scientifically verify the folkloric use. Forced swim test (FST) and phenobarbitone induced sleeping time test were the neuropharmacological models employed in the study. Results showed that the root bark of Voacanga africana extract (VAE) showed abolition of depressive-like behavior in the FST in a dose dependent fashion, with VAE (400 mg/kg) and amitriptyline (15 mg/kg), showing highest reduction of the immobility time to 70.40 and 49.50 seconds from 133 second of the control, respectively. The extract also significantly (p < 0.05) and dose dependently, potentiated the onset of sleep and duration of sleep in phenobarbitone induced sleeping time in tested animals. At 400 mg/kg dose VAE almost doubled the duration of sleep while diazepam (3 mg/kg), a standard agent, tripled same parameter. However, the acute toxicity test showed that the extract gave an estimated LD 50 of 1250 mg/kg. In conclusion, the extract of Voacanga africana possesses antidepressant and sedative activities thus confirming its use in the treatment of psychiatric disorders in folk medicine. Keywords: Voacanga africana, antidepressant, forced swim test, rats. INTRODUCTION epression is a common life threatening psychiatric disorder that negatively affects the mood, feelings and thoughts of an individual. It usually interferes with the quality of life of the individual and at same time causing feelings of sadness, loss of interest in activities once enjoyed, withdrawing from social life, dejected or feeling of worthlessness . 1 However, according to World Health Organization (WHO) reports, depressive disorders and anxiety disorders are the two common mental disorders affecting the global population. 2 It has been estimated that over 300 million people suffer from depression globally which is about 4.4% of the world’s population. Depression is often associated with decreased quality of life, disability, increased cost of healthcare, poverty and risk factor to other health disorders. 3 Many a times depression may lead to suicide and estimates have it that about one million lives are lost to suicide annually representing a total of about 3000 suicides per day. 4 Standard agents employed in the management of depressive disorders often have limited efficacy with attendant serious side effects, hence the need to discover new therapeutic agents from natural sources is of paramount importance. One of the medicinal plants used in Nigerian ethnomedicine for the treatment of depressive disorders is the root bark preparation of Voacanga africana Stapf. (Apocynaceae). V. africana has been reported to possess antiulcer [5] , antiamoebic and antispasmolytic, 6 anti-addictive as well as psychedelic 7 activities. Therefore, this study was designed to evaluate the antidepressant activities of V. Africana root bark extract using neuro-pharmacological models. MATERIALS AND METHODS Animals Adult albino mice (18-30 g) of either sex were used for the phenobarbitone induced sleep time test and acute toxicity test, while adult Sprague-Dawley rats (150-250 g) of either sex were used for forced swim test. The animals were maintained with a 12 hour light/dark cycle, allowed free access to food and water prior to behavioural experiment and were transported in their cages to the laboratory 30 minutes before the experiment to get acclimated. All animal experiments were conducted in compliance with the National Institute of Health Guide for Care and Use of Laboratory Animals (Pub No. 85-23, revised 1985) and in accordance with the University of Nigeria Ethics Committee on the use of laboratory animals, registered by the National Health Research Ethics Committee (NHREC) of Nigeria, with the number; NHREC/05/01/2008B. Extraction of plant materials Fresh root barks were collected in the month of November, from Nsukka, Enugu State, Nigeria; and were botanically identified by Mr. A. Ozioko of International Center for Ethnomedicine and Drug Development (InterCEDD), Nsukka, Nigeria. The fresh root bark was rinsed, air dried under the shade and milled to a coarse Studies on the Antidepressant Effect of Root Bark Extract of Voacanga africana in Murine Models D Research Article