_____________________________________________________________________________________________________ *Corresponding author: E-mail: si.egba@mouau.edu.ng, simeonegba@yahoo.com; Annual Research & Review in Biology 18(3): 1-8, 2017; Article no.ARRB.36598 ISSN: 2347-565X, NLM ID: 101632869 Down-regulatory Influence of Methanol and Aqueous Root Extracts of Sphenocentrum jollyanum on Some Fertility Hormones and the Effect on Testicular Size of Wistar Albino Rats S. I. Egba 1* , H. C. Omeoga 1 , C. E. Oriaku 1 , E. C. Jacob 1 , F. C. Nnabugwu 1 , J. C. Lazarus 1 and E. N. Echem 1 1 Department of Biochemistry, College of Natural and Applied Sciences, Michael Okpara University of Agriculture, Umudike, Abia State, Nigeria. Authors’ contributions This work was carried out in collaboration between all authors. Author SIE designed the study, carried out laboratory analysis and wrote the manuscript. Authors HCO and CEO took care of the animals, carried out statistical analysis and wrote first draft of the manuscript while authors ECJ, FCN, JCL and ENE also catered for the animals, administered extracts and managed the literature searches. All authors read and approved the final manuscript. Article Information DOI: 10.9734/ARRB/2017/36598 Editor(s): (1) Yalemtsehay Mekonnen, College of Natural Sciences, Addis Ababa University, Ethiopia. (2) George Perry, Dean and Professor of Biology, University of Texas at San Antonio, USA. Reviewers: (1) Dinithi Peiris, University of Sri Jayewardenepura, Sri Lanka. (2) Divya S. Rajan, Kerala University, India. Complete Peer review History: http://www.sciencedomain.org/review-history/21380 Received 1 st September 2017 Accepted 27 th September 2017 Published 13 th October 2017 ABSTRACT Objective: The study is aimed at investigating the effects of oral administration of aqueous and methanol extract of the root of Sphenocentrum jollyanum on testicular size, testosterone, follicle- stimulating hormone, luteinizing hormone and prolactin levels in male Wistar albino rats. Methods: A total of 24 Wistar albino rats of equal sexes were randomly distributed into three groups having 4-rats each of both sexes. Group 1 served as the control and was administered distilled water ad libitum while groups 2 and 3 were administered 400 mg/kg body weight methanol and aqueous extracts respectively. Oral administration lasted for 14 days at the end of which animals were sacrificed and blood samples were collected from all the groups through ocular Original Research Article