Thesis Abstract

<p>               <b>     ABSTRACT&nbsp;</b></p><p>The bark of the West African Pausinystalia yohimbe tree is a traditional aphrodisiac and the source of yohimbine, a prescription drug for impotence. It appears to be modestly effective, but it also presents numerous safety risks. The possible side effect on the haematological parameters and histology of the hypothalamus has not been considered. This study investigated experimentally using adult male Wistar rats, the changes in haematological parameters and the histology of the hypothalamus due to oral administration of the crude extract Pausinystalia yohimbe bark. Thirty six (36) adult male Wistar rats of average weight of 200g, used for this experiment. The animals were grouped into four (4) groups of nine (9) animals per group. With group I serving as the control and administered distilled water. While group II, III and IV administered 30mg/kg, 50mg/kg and 100mg/kg body weight per day of the crude extract of Pausinystalia yohimbe bark orally respectively, for three (3) weeks. Blood samples were collected from all the animals for the haematological studies and the brain tissues were also collected and fixed in Bouin’s fluid and processed for histological studies using the method of Glee’s. The photomicrographs of the tissues were taken using&nbsp; an Optical Eye Piece connected to a computer system. The results showed that the Pausinystalia yohimbe bark extract produced significant increased in the erythrocytes count values, total protein and clothing time decrease in the leukocyte count, monocyte and eosinophils differential counts. The extract also has excitatory effect on the nuclei of the hypothalamus, indicating cellular hyperplasia. &nbsp;<br></p>

Thesis Overview

<p> Presently, there is a growing interest in the use of natural products. Various products of plant origin are being marketed in Nigeria. They range from herbal toothpastes to various drug supplements. Some of these herbal preparations may have some inherent properties, which have contributed to their persistent use over the years, underscoring the need for validation of some or most of them. It is said that only about 2% of all the plants on earth have been subjected to pharmacological investigation. The rationale for the utilization of medicinal plants has rested largely on long term clinical experience with little or no scientific data on their efficacy and safety (Zhu et al., 2002). With the upsurge in the use of herbal medicines, a thorough scientific investigation of these plants is imperative, based on the need to validate their folkloric usage (Sofowora, 1989). There is paucity of information in the scientific literature on the toxicity profile of Pausinystalia yohimbe. But since sub-acute or sub-chronic toxicity data will be required to predict the safety or otherwise of long-term low dose exposure to medicinal products (McNamara, 1976), it is necessary to provide this information in order to bridge the gap in knowledge about the effect of Pausinystalia yohimbe on the haematological parameters and the histology of the hypothalamus. Such data may play a critical role in the continued ethano-medicinal applications of the plant and assist future development of ethno-medicine from it. <br></p><p> In a typical traditional African setting, satisfactory sexual performance is most often equated to masculine prowess. A man who fails to have a satisfactory sexual performance is said to have lost his manhood. Again, the issues of sex and sexual relationship is not greatly discussed in the traditional African setting, with the result that when men are plagued with erectile dysfunction, they tend to recede to the privacy of their bedrooms, ruminating over their seeming loss of manhood and willing to clench to any form of affordable and available remedy that they come across in order to restore their lost manhood. And due to the high cost of modern drugs which are used to improve or enhances sexual performance or correct erectile dysfunction, such men go for the easily affordable local herbs available in the homes of traditional medicine practitioners or readily available herbal products being sold cheaply at local markets, motor parks or in luxurious buses. Such local herbs that are purchased from these mentioned places may present with unknown side effects and numerous complications. An assessment of the therapeutic or toxic effects becomes necessary because these medicinal plants are locally available and relatively cheap to purchase by most people. When these herbal remedies have been tested and proven to be non-toxic, safe and inexpensive and culturally acceptable, then their usage can be encourage. Many herbal combinations have been used to enhance sexual performance or to treat erectile dysfunctions. Better MAN TM is a clinically tested Chinese’s herbal supplement that improves sexual performance and prostate health. Others includes Ginkgo biloba, Cateaba (Erythroxylum catuaba), Marapuama (Ptychopetalum olacoides), Pygeum (Pygeum africana), Yohimbe (Pausinystalia yohimbe) (Sohn et al., 1991). <br></p><p> 1.2 Pausinystalia yohimbe&nbsp;</p><p>&nbsp;Pausinystalia yohimbe is also known as Corynanthe yohimbe. Another common name is Yocon.While in Hausa it is called Dankamaru <br></p><p> <b>1.2.1 Botanical information&nbsp;</b></p><p>It is an evergreen tree which grows to a height of 30m with a spread of 8m. The stem is erect and branching, the leaves are oval, acuminate and about 10cm long. The seeds are small winged silvers, almost paper thin. Pausinystalia yohimbe is a native of the rainforest of Nigeria, Cameroon and the Congo. It prefers rich soils in a protected part sun to shady position, and is drought and frost tender. The propagation of Pausinystalia yohimbe is by seed or cutting. Seeds are sown in a free draining seed mix or sphagnum moss and will need temperatures above 250C to germinate quickly. Seeds have a very short viability, which declines rapidly in dry and warm conditions. (Shaman Australis Botanicals, 1998).<br></p><p> <b>1.2.2 Traditional Uses&nbsp;</b></p><p>Yohimbe is the only natural medicinal aphrodisiac. Its use as an aphrodisiac in its native area has been well documented and its unique effects were soon valued in many parts of the world, especially in Europe. In modern times yohimbe products have found a wide market, ranging from medically treated impotency and self administered sexual enhancement to “smart products” like “cloud 9” ™ and other herbal ecstasy formulations. <br></p><p> <b>1.2.3. Pharmacology&nbsp;</b></p><p>There are several alkaloids in Pausinystalia yohimbe, but it is the yohimbine which is an indole alkaloid somewhat similar and related to ibogaine and mitragyine and is present in the bark of this species to between 2 and 15%. Yohimbine is found in nature from the bark of the Pausinystalia yohimbe tree and is used for treatment of impotence. Yohimbine is the active constituent and acts by blocking alpha-2 adenoreceptors centrally. As a result, there is an increase in release of norepinephrine and increases in cholinergic activity. Yohimbine also inhibits monoamine oxidase that is responsible for the breakdown of norepirephrine and serotonin without increasing testosterone level (Wepser, et al., 1999). Yohimbe has been used for centuries in African folk medicine to treat leprosy, coughs, treat fevers, as a local anesthetic, sexual aphrodisiac, etc. African tribal men would often chew on the bark prior to going to battle to increase strength. However, its most popular use has been as an aphrodisiac and to improve erections. Yohimbine also increases blood levels of the neurotransmitter norepirnephrine. Norepinephrine stimulates the brain’s sex center in the hypothalamus and is considered one of the body’s natural prosexual chemicals. <br></p><p> <b>1.3 STATEMENT OF THE PROBLEM</b></p><p>&nbsp;Although crude yohimbe bark preparations are available commercially, there are no commercial sources of yohimbe bark that are available to physicians or in health food stores which actually state the level of yohimbe per dosage. Without knowing the content of yohimbe, it is virtually impossible to prescribe an effective and consistent dosage. Because of the yohimbine content of yohimbe bark, the American Food and Drug Administration (FDA) classifies yohimbe as an unsafe herb. But in many developing countries, especially Nigeria, yohimbe is still being taken indiscriminately. <br></p><p> 1.4 AIMS AND OBJECTIVES&nbsp;</p><p>The aims and objectives of this study are to experimentally investigate:&nbsp;</p><p>1. The possible changes in hematological indices as a result of oral consumption of Pausinystalia yohimbe in adult male Wistar rats.</p><p>&nbsp;2. The possible histological changes in the hypothalamus of adult male Wistar rats <br></p>