The relationship between autophagy activation in spinal cord and type 2 diabetic neuropathic pain in rats / 中国应用生理学杂志

OBJECTIVE@#To investigate the relationship between autophagy function in spinal cord and type 2 diabetic neuropathic pain in rats.@*METHODS@#Forty-two male Sprague-Dawley rats were fed with a high-sugar, high-fat diet for 8 weeks to induce the insulin resistance, and then received a single intraperitoneal streptozocin (STZ) injection to establish type 2 diabetes rat model. Two weeks after STZ injection, mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) of rats were detected, the rats with MWT and TWL decreasing to below 80% compared to baseline were chosen as type 2 diabetic neuropathic pain rats (group DNP, =24), the rest of the rats were chosen as type 2 diabetic non-neuropathic pain rats (group DA, =18). And another 18 normal rats randomly selected from the total were classified as control group (group C) and fed with common forage for 8 weeks. The MWT and TWL were measured again on the 3rd, 7th and 14th day after determining the grouping of DA and DNP, and then, the lumbar segments 4~6 of the spinal cord were removed from the executed rats for determination of the expressions of microtubule-associated protein light chain 3 (LC3)、Beclin-1and P62 by Western blot. The co-expressions of P62 with GFAP or OX-42 or NeuN in spinal dorsal horn were detected in another 6 lumbar segments of diabetic neuropathic pain (DNP) rats on the 7th day by immunofluorescence double dye method.@*RESULTS@#Compared with group C, the insulin level was increased and ISI decreased in SD rats fed with high-sugar, high-fat diet, that meant the rats in insulin-resistance. After STZ injection, blood glucose rose to the standard of type 2 diabetes mellitus, i.e. ≥ 16.7 mmol/L. Compared with group C and group DA, MWT was significantly decreased, TWL shortened and the expression of LC3-Ⅱ and Beclin-1 in the spinal dorsal horn up-regulated, P62 expression down-regulated on the 3rd, 7th and 14th day in group DNP (<0.05). P62 was mainly localized in spinal dorsal horn and coexisted with neurons, and spots of P62 immunoreactivity could be detected in a few microglia but not observed in astrocyte.@*CONCLUSIONS@#The changes in expression of LC3-Ⅱ、Beclin-1 and P62 in spinal cord of type 2 diabetes neuropathic pain rats means autophagy activation of spinal, up-regulated autophagy of neurons in spinal dorsal horn mainly involves in the formation and development of type 2 diabetic neuropathic pain in rats.

Acute effects of anaerobic exercises by a bicycle ergometer on elastic modulus and local hemodynamics in common carotid arteries / 医用生物力学

Objective To investigate acute effects of anaerobic exercises by a bicycle ergometer on arterial elastic modulus and local hemodynamics in human common carotid arteries with different genders. Methods Nine male and eight female healthy young volunteers at the age of 20-30 year-old successively underwent four groups of exercise trainings with the same workload by an anaerobic bicycle ergometer. The waveforms of arterial diameter and center-line blood velocity were measured in the right common carotid artery using a color Ultrasonic Doppler for each group when at rest and right after exercise training. The heart rate, systolic and diastolic blood pressures were simultaneously measured in brachial artery using an automatic electronic sphygmomanometer. All the measured data were analyzed based upon the principle of classic hemodynamics. The arterial elastic modulus and local hemodynamic parameters, including pressure-strain elastic modulus, flow rate, circumferential strain, wall shear stress and oscillatory shear index (OSI), were then calculated. Results The heart rate and arterial elastic modulus increased after exercises; with the accumulative exercises, in one cardiac cycle, the maximum and mean center-line velocity and flow rate increased while the minimum velocity and flow rate decreased; the systolic and mean blood pressure increased while diastolic blood pressure exhibited no significant change; no significant change could be found in the circumferential strain; the maximum and mean shear stress increased significantly while the minimum shear stress reduced; the oscillatory shear index also increased. Conclusions The anaerobic exercises by a bicycle ergometer may increase the arterial elastic modulus and induce significant effects on local hemodynamic parameters in common carotid arteries for young volunteers with different genders at the age of 20 30 year old. The results in this study could provide useful hemodynamic information for regulation of cerebrovascular function by anaerobic exercises.