| AimDiabetes mellitus ( DM) is a metabolic disease characterized by disorder of glucose metabolism induced by absolute or relative deficiency of insulin. Kinds of complications will be induced if DM cannot be controlled effectively on time, such as pain peripheral neuropathy and inflammatory reaction. The change in vascular permeability induced by DM results in cardiovascular complications, which increase morbidity of hypertension and stroke.Dorsal root ganglion ( DRG) is very vulnerable in DM, and particularly susceptible to microangiopathy. DRG is a direct target of diabetes damage. In long - term diabetes, degeneration of peptidergic primary afferent nerve system accounts for the early sensory abnormalities in diabetes and the development of neuropathy complication.Calcitonin gene - related peptide ( CGRP) distributes in neurons of brain tissue and spinal cord. In peripheral system, CGRP mainly exists in sensory ganglions, such as trigeminal ganglion ( TG) and DRG, and usually concomitant with other neural transmitters, such as substance P (SP). Cyclooxygenase - 2 ( COX - 2) also coexists with it. In long - term DM, blockade of direct transportation of CGRP and SP results in the decrease of CGRP in blood and sensory neuron and attenuation of response to CGRP of vessels. All of these changes participate in increasing of nociceptive reaction and allodynia in diabetes.COX-2 gene is a small (8. 3kb) immediate early gene, an isoform of COX - 1, participates in synthesis of prostaglandins ( PG) that related to inflammatory process. In DM the induction of COX - 2 results in increased gene expression, which followed by increased PGs synthesis, especially PGE2. Increased activity of COX - 2 in smooth muscle cell induces over production ofPGs in blood. So the induction of COX - 2 is a risk factor of diabetes.ATP - sensitive potassium channel ( KATP) is a member of inward rectifying potassium channel, and is controlled by concentration intracellular of ATP. So far, it was found many tissues and cells containing KATP. KATP plays a key role in physiological and pathological functions. Many endogenous vasoactive agents come into effect partially by activating KATP on arterial smooth muscle cells. In normal condition, when the pressure of circulation decreases, sensory neurons on arterial adventitia release CGRP, in turn, CGRP activates adenosine cyclase and increases cAMP, activation of KATP that followed by cAMP increase dilates artery to maintain enough and steady blood flow. In diabetes, the reasons of decreased vasodilation comprises two: one is synthesis and release of vasodilators decrease; another is attenuation of dilating function, which opening function of KATP decrease. It was reported that diabetes usually affected relaxation capacity of vascular complication in diabetes, such as atherosclerosis, coronary heart disease , hypertension, etc .The objectives of the present study were (1) to determine the change in synthesis of CGRP mRNA in DRG, COX -2 mRNA in DRG and aorta, as well as corresponding products of them in different period of short - term diabetes ( <2 months) ; (2) to claim the mechanism of diabetes vascular complication further, and to provide theoretical basis of prevention and treatment of diabetes complications.MethodsMale Wistar rats were divided into control and experimental diabetes groups. Streptozotocin (STZ) was dissolved in 0.05M ice trisodium citrate buffer (pH 5.0). Experimental diabetes were induced by STZ (60mg/kg) by single intraperitoneal injection. The controls received STZ citrate buffer carrier a-lone. Rats were accepted as diabetic if the whole - blood glucose level was higher than 16mmol/L. Glucose was measured with a glucometer in whole blood taken from tail vein. Then diabetes rats were divided into four groups, i. e. 1-week - diabetes (1w) , 3 - week - diabetes ( 3w) , 4 - week - diabetes (4w) ,8 - week - diabete (8w) rats.Rats were anesthetized, and vein blood was drawn from right heart, then centrifuged at 3000 rpm, 4℃. Plasma was removed, and...
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