HEALTH IMPLICATION OF STEROID FATTENED LIVESTOCK AND THE IMPLICATION OF THEIR LIPID PROFILE FOR HUMAN NUTRITION
CHAPTER ONE
1.0 INTRODUCTION
1.1 BACKGROUND OF STUDY
Hormones are chemicals produced by animals to co-ordinate their physiological activities. They acts as messengers, produced in and released from one kind of tissue to gradually stimulate or inhibit some process in a different tissue over a long period. The importance of individual hormones varies between sexes and age and a disruption of the endocrine equilibrium may result in multiple actions e.g the male hormone testosterone controls many processes from the development of foetus to libido in the adult. Alternatively, one function may be controlled by multiple hormones, e.g. the menstrual cycles involves estradiol, progesterone, follicle stimulating hormone and luteinizing hormone. Hormones are vital in normal development, maturation and physiological functioning of many vital organs and processes in the body (Annamaria, 2012).
However, like any other chemicals of natural or synthetic origin, hormones may be toxic to living organisms under certain circumstances. The toxicity may be due to an excess of its normal (physiological) action. Hormones, like other chemicals, may also exert direct toxic actions not related to their endocrine (physiological) actions (Annamaria, 2012). Besides the endogenous corticosteroids (cortisol, cortisone) and those suspected to be endogenous (prednisone, prednisolone), there are synthetic exogenous corticosteroids (dexamethasone, betamethasone), developed because of their anti-inflammatory properties. Estrogens, androgens, gestagens and corticosteroids are steroids which act as hormones. The parent compound from which all steroids are derived is cholesterol. The classification of steroid hormones can be done according to their biological activity and pharmacological effects which includes the sex steroids, a subset of hormones producing sex differences and reproduction such as estrogen, gestagens and androgens. The second group is the corticosteroids which are glucocorticosteroids, involves in metabolism and immune function and mineralocorticosteroids, involves in the regulation of the blood volume and electrolyte content. They can also be classified upon their endo or exogenous origin. Steroid hormones that are biosynthetically present in the body are the endogenous hormones and they are chemical messengers from one cell (or group of cells) to another e.g (estradiol). Exogenous steroids are also called xenobiotics are foreign compounds that are naturally or synthetically produced e.g methyltestosterone (Noppeet al., 2008).
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