APHRODISIAC AND REPRODUCTIVE STUDIES ON METHANOL ROOT BARK EXTRACT OF SECURINEGA VIROSA (ROXB. EX. WILLD.) BAILL IN MALE WISTAR RATS

ABSTRACT

Securinega virosa (SV) is a widely used plant in traditional medicine. The root is used as an aphrodisiac in north western Nigeria. The aim of the study was to provide pharmacological rationale for the ethnomedical use of the root of Securinega virosa as aphrodisiac as well as to establish its general male reproductive effects. A total of twenty four male wistar rats were randomly divided into four groups of six animals each (n=6), and used to assess the aphrodisiac potential of the extract which includes; mounting, intromission, ejaculation frequencies and latencies. Female Wistar rats used for pairing were brought to estrus phase of their reproductive cycle using oral suspension of ethinyl oestradiol (100 μ/ml/ animal), 48 hours prior to the pairing plus progesterone at a dose of I mg/animal injected subcutaneously, 6 hour prior to the experiment. For the assessment of male reproductive functions, a total of sixty (60) male Wistar rats were randomly divided into four groups (A, B, C, D) each consisting of fifteen (n=15) rats. Groups B, C and D were administered with the extract of Securinega virosa once daily at 24 hours interval at different graded doses of (31.25 mg/kg, 62.5mg/kg, and 125 mg/kg) respectively for 21 days. The rats in group A served as control and received 1ml/kg of distilled water for the same number of days. The extract significantly (P< 0.05) improved mating behavior, increased intromission frequency (IF) at 125 mg/kg, and significantly decreased (P< 0.05) ejaculatory latency (EL) at 31.20 mg/kg. Serum testosterone (ng/ml) level was significantly increased (P< 0.05) following first week of administration at doses of SV 62.50 mg/kg and 125 mg/kg; and also at third week of administration at dosage of SV 62.50 mg/kg. Serum LH (ng/ml) also increased at dose of 62.50 mg/kg following both first and the third week, while serum FSH (ng/ml) increased at 62.50mg/kg after the third week of administration. The extract caused a significant increase (p<0.05) in sperm motility, sperm count, sperm morphology and viability. There was a significant (p< 0.05) decrease in body weight at all the doses tested. The extract caused a significant increase (p< 0.05) in the weight of testes, epididymis and vas deferens weight (g). Histology of the rats treated with the highest dose showed normal seminiferous tubules with a markedly increased concentration of mature spermatozoa relative to the control. It is concluded that the methanol root bark extract of Securinega virosa possesses aphrodisiac activity with concurrent beneficial effects on sperm parameters.

CHAPTER ONE

1.1 Introduction

The main aim of marriage is the procreation (reproduction) of the organism and for the sexual fulfillment of both partners. In order to prevent extinction of an organism, the organism must be able to reproduce itself before it dies. In human beings, reproduction is initiated when a male and female are involved in a sexual intercourse, which allows the fusion between the sperm from the male and egg from the female to form a zygote, which develops into a fetus (Fullick, 1994).

Normal sexual intercourse and fulfillment can only occur in males when the male sexual organs (the copulatory organ, the penis) and factors relating to erection are functioning normally. Inability to perform this function effectively is known as sexual dysfunction, and it is a problem of the reproductive process (Guay et al., 2003). The increasing incidence of male sexual dysfunction has necessitated an increase in the patronage of aphrodisiacs; this has invariably resulted in an increase research into the beneficial effects of these medicinal plants, as well as their general effects on male reproductive function. Some of the medicinal plants that have been proven to have aphrodisiac potentials in male rats includes: Terminalia catappa seeds (almond fruit), Syzygium aromaticum flower bud (clove), Fadogia agrestis stem (Black aphrodisiac) (Ratnasooriya et al., 2000; Yakubu et al., 2005).

Erectile dysfunction is best defined as persistent failure to generate sufficient penile body pressure to achieve vaginal penetration and/or the inability to maintain penile rigidity until ejaculation. Many commonly prescribed pharmacological agents can adversely influence sexual function of the male. Mechanisms by which some medications can induce erectile dysfunction may include central and/or peripheral neurological blockade or stimulation of prolactin (PRL) secretion. Hyperprolactinemia may reduce testosterone concentration and action through a variety of mechanisms including disruption of the anatomic integrity of the hypothalamic-pituitary axis, decreased GnRH expression, interference with GnRH action on the pituitary, inhibition of gonadotropin secretion, and reduction of testosterone conversion to the more active metabolite dihydrotestosterone. Hypogonadism has recently been shown to be associated with decreased nitrogen oxide (NO) formation and action in the penis, thus reducing erectile capacity (Lugg et al., 1995; Fouad et al., 2001).

1.2 Statement of Research Problem

Male sexual dysfunction is one of the most common health problems affecting men and is more common with increasing age. It can be caused by physical or psychological problems. Sexual dysfunction can lead to infertility, which is the inability of a sexually active non-contracepting couple to achieve pregnancy in one year of unprotected, regular intercourse(WHO, 2000). This has led to the end of several marriages. About 15% of couples do not achieve pregnancy within 1year; almost 50% of them do so spontaneously in the second year of unprotected intercourse, and another 14% in the third year. Ultimately, less than 5% remain childless (Te Velde and Pearson, 2002). Throughout all ages, men and women have incessantly pursued every means to increase, preserve and recapture their sexual capacity, or to stimulate the sexual desire of selected members of the opposite or same sex. One of the most recurrent methods has been the use of aphrodisiacs. Herbal medicines are a major source of aphrodisiacs and have been used worldwide for thousands of years by different cultures and civilizations. However, a deeper understanding of phytochemistry, pharmacognosy and ethnopharmacology is fairly available to support the production of new and safe pharmacologically active compounds with minimal undesired toxic effects. In infertile couple, there is often a coincidence of male and female factors. With routine medical investigations for infertility, no cause can be found in about 10-15% of infertile couple. In the cases of infertility recorded, the male factor contributes 45-50% of cases (WHO, 2000).

1.3 Justification of Study

Sexual dysfunction is a major medical and social issue that affects the general populace. It has led to the end of several homes and increasing challenges to the nation at large. Several orthodox medications such as Sildenafil citrate (Viagra), Vardenafil (Levitra), Tadalafil (Cialis), Apomorphine (Uprima) have been used in the treatment of sexual dysfunctions. However, with increasing side effects, high cost of obtaining synthetic drugs and failure of treatment, there has been renewed vigorous interest in the medicinal herbs with folkloric use for sexual dysfunction.

Medicinal plants are extensively used as aphrodisiac to manage sexual dysfunction (Yakubu et al., 2007). One of such plants claimed to have aphrodisiac potentials is Securinega virosa; however, there is paucity of data on its effectiveness in sexual dysfunction as well as it reproductive safety. This study is therefore directed at the investigation of the methanol root bark extract of Securinega virosa for aphrodisiac properties and its effects on male reproductive functions.

1.4 Aim and Objectives

1.4.1 Aim of study

The aim of the study was to provide pharmacological rationale for the ethnomedical use of the root of Securinega virosa as aphrodisiac as well as its general effects on male reproductive function.

1.4.2 Specific objectives.

The objectives of the study were to:

i. To establish the acute toxicity profile of the methanol root bark extract of Securinega virosa.

ii. To establish the preliminary phytochemical profile of the methanol root bark extract of Securinega virosa.

iii. Establish the effect of the methanol root bark extract of Securinega virosa on male reproductive functions viz; serum Testosterone, Luteinizing hormone, Follicle stimulating hormone, sperm motility, count, viability, morphology and testicular histology.

iv. Establish the aphrodisiac potential of the methanol root bark extract of Securinega virosa on male Wistar rats

1.5 Research Hypothesis

Methanol root bark extract of Securinega virosa possesses significant aphrodisiac activity and significantly enhances serum testosterone, FSH, LH and sperm parameters