American Journal of Pharmacology and Toxicology 1 (1): 5-10, 2006 ISSN 1557-4962 © 2006 Science Publications Corresponding Author: Kamal Mohmoud Saleh Mansi, Department of Biological Sciences, Al al-Bayt University, Al- Mafraq, Jordan, Telfax: 0096265151261, Mob.: 00962777357681 5 Effects of Administration of Alpha-Melanocyte Stimulating Hormone (-MSH) on Some Hematological Values of Alloxan-induced Diabetic Rats Kamal Mohmoud Saleh Mansi Department of Biological Sciences, Al al-Bayt University, Al-Mafraq, Jordan Abstract: This study was designed to evaluate the role of alpha- melanocyte stimulating hormone (- MSH) on heart rate and some hematological values in alloxan induced diabetic rats. 40 male white rats were divided into four experimental groups: control, diabetic, -MSH-treated and -MSH-treated diabetic. At the end of the experimental period (3weeks), animals in all four groups were fasted for 12 hrs and blood samples were taken for the determination of plasma insulin, Glucagon, glucose levels, RBC and WBC (red and white blood cell) counts, packed cell volume (PCV), erythrocyte sedimentation rate (ESR) and hemoglobin (Hb) concentration. It was found that (-MSH) increased the lowered RBC and WBC counts, PCV and neutrophil percentage in diabetic rats. However the WBC counts of the (-MSH) treated diabetic group was still lower than the control and (-MSH) group. (- MSH) also decreased the elevated heart rate, ESR and glucose concentration of diabetic rats. The hormone was investigated for hypoglycemic effect in diabetic rats and induced not significant reduction in serum glucose from (19.83±1.25 MmolL) in diabetic group to (15.7±1.10 MmolL) in (- MSH)-treated diabetic group. However the blood glucose still higher than the control and (-MSH) group, serum insulin increased from (0.55±0.08 ng mL 1 ) in control group to (0.65±0.06 ng mL 1 ) in - MSH-treated group and still higher than control in -MSH-treated diabetic (0.59±042 ng mL 1 ) and serum Glucagon increased in diabetic, -MSH-treated and -MSH-treated diabetic groups. It is concluded that treatment (-MSH) might decrease the diabetes-induced disturbances of heart rate and some hematological parameters of alloxan-induced diabetic rats. Key words: Alpha-MSH, alloxan, hypoglycemic agents, insulin, heart rate, hematological values INTRODUCTION Diabetes Mellitus (DM) represents a heterogeneous group of disorders that have hyperglycemia as a common feature [1,2] . Al though Diabetes has long been considered a disease of minor significance, it is considered now as one of the main threats to human health in 21st century. Great changes in the human environment, behavior and lifestyle resulted in the raising rates of Diabetes [3] . (DM) is consequence of defects in secretion, insulin action or both, which is translated into abnormalities of carbohydrate, fat and protein metabolism resulting in hyperglycemia [4,5] . Symptoms of chronic hyperglycemia include polyuria, polydipsia and polyphagia as well as weight loss. Although varying among patients, long term complications of Diabetes can also include changes in arteries (arteriosclerosis), basement membranes of small vessels (microangiopathy), (kidneys (nephropathy), retina (retinopathy) and nerves (neuropathy) [6-8] . DM leads to many complications, such as increasing the risk of developing arterial disease by two to six folds [9] . It has been suggested that the heart rate is higher, red and white blood cells counts lower in type diabetes than in non-diabetic [10,11] . There is some evidence that diabetics present a deficiency in mounting an inflammatory response, probably associated with severe reduction in insulin secretion rather than increased blood glucose levels [1,2,13] . This is still a controversial point as other investigators have suggested a direct correlation between hyperglycemia and the incidence of infection in diabetic patients [14] . Alpha-melanocyte-stimulating hormone (Alpha - MSH) is a tridecapiptide that was originally characterized a neuropeptide derived from a pituitary - MSH is hormone derived by post-translational processing from POMC and involved in stress and background adaptation. Alpha-MSH is synthesized from pro-opiomelanocortin (POMC) by the action of specific prohormone convertases that cleave into - MSH, ACTH and Beta-endorphin. Alpha-MSH seems to be modulated by the release of two hormones within the hypothalamus: melanoncyte stimulating hormone releasing factor (MSHRF) and melanocyte stimulating hormone release-inhibiting factor (MSH-RIF). Five G-protein-coupled melanocortin receptors (MC (1)-MC (5)) are expressed in mammalian tissues. The melanocortin receptors support diverse physiological functions, including the regulation of hair color, adrenal function, energy homeostasis, feed efficiency, sebaceous gland lipid production and immune and sexual function. The hormone is a