BACKGROUND: Previous studies suggest that systemic administration of agmatine, endogenous ligand for imidazoline receptors has anti-hypernociceptive effects in experimental animal. However the peripheral effects of agmatine on inflammatory pain have not yet been elucidated. Here we examined the effects of intra-articular injection of agmatine in the induction and maintenance phase of arthritic pain. In addition, we sought to determine the potential contribution of imidazoline and alpha(2)-adrenergic receptors to the antinociceptive effects using clonidine which is mixed alpha(2)-adrenoceptor and imidazoline receptor agonist. METHODS: To induce arthritis in rats, 2% lambda-carrageenan (50microliter, in saline) was injected into the joint of the right hind limb under enflurane anesthesia. Either agmatine (10, 50, 100microgram/40microliter) or clonidine (10, 50, 100microgram/40microliter) was injected into the knee joint cavity immediately before or 4 hr after carrageenan injection. Weight load tests were performed to measure pain-related behavior in freely walking rats. RESULTS: The intraarticular injection of agmatine into the knee joint had no effects in the both phase of induction and maintenance of arthritic pain at any dose tested. However, injection of clonidine reversed arthritic pain, when injected 4 h after carrageenan injection. CONCLUSIONS: In rats, agmatine has no peripheral effect on inflammatory pain and imidazoline receptors in the periphery may not contribute to the anti-inflammatory pain.
Agmatine ; Anesthesia ; Animals ; Arthritis ; Carrageenan ; Clonidine ; Enflurane ; Extremities ; Imidazoline Receptors ; Inflammation ; Injections, Intra-Articular ; Joints ; Knee ; Knee Joint ; Rats ; Walking

BACKGROUND: Increased abdominal obesity is clearly associated with metabolic diseases and associated with increased risk for atherosclerosis and cardiovascular diseases. But the mechanisms underlying these associations are not completely understood. The aim of this study was to correlate the regional body composition with pulse wave velocity in the overweight and obese women. METHODS: We investigated 104 overweight and obese participants. Regional body composition was distinguished by anthropometry, dual-energy X-ray absorptiometry, and computed tomography (CT). For estimates of arterial stiffness, we measured brachial ankle pulse wave velocity (baPWV). Fasting blood glucose, lipid parameters, CRP, and free fatty acid were measured. Pearson's correlation analysis and multiple regression analysis were conducted to identify the relationship between baPWV and regional body composition. RESULTS: Average age, fasting blood sugar, HDL-cholesterol, triglyceride, HOMA-IR, abdominal visceral fat area measured by CT, visceral fat area/ subcutaneous fat area (VSR), and visceral fat area/midthigh muscle area (VMR) were all significantly higher in the visceral obesity group than the subcutaneous obesity group. BaPWV was positively correlated with age, blood pressure, triglyceride, waist circumference, waist hip ratio, abdominal visceral fat area measured by CT, and VSR and inversely correlated with thigh subcutaneous fat area. In multiple regression models, after adjustment for confounding factors, baPWV was independently correlated with abdominal visceral fat area measured by CT (R2=0.560, P=0.006). CONCLUSION: Abdominal visceral fat area measured by CT was the only measurement positively associated with baPWV which explains the relationship of regional body composition and arterial stiffness.
Abdominal Fat* ; Absorptiometry, Photon ; Ankle ; Anthropometry ; Atherosclerosis ; Blood Glucose ; Blood Pressure ; Body Composition ; Cardiovascular Diseases ; Fasting ; Female ; Humans ; Intra-Abdominal Fat ; Metabolic Diseases ; Obesity ; Obesity, Abdominal ; Overweight* ; Pulse Wave Analysis ; Subcutaneous Fat ; Thigh ; Triglycerides ; Vascular Stiffness* ; Waist Circumference ; Waist-Hip Ratio