Protective effect of mulberry flavonoids on sciatic nerve in alloxan-induced diabetic rats

Mulberry leaves (Morus alba L.) are a traditional Chinese medicine for blood serum glucose reduction. This study evaluated the protective effects of mulberry flavonoids on sciatic nerve in alloxan-induced diabetic rats. In this study, 80 Sprague-Dawley rats were divided into five groups: A (control), B (diabetic treated with saline), C-D (diabetic treated with 0.3, 0.1 g/kg mulberry flavonoids once a day for 8 weeks) and E (diabetic treated with 0.3 mg/kg methycobal). The diabetic condition was induced by intraperitoneal injection of 200 mg/kg alloxan dissolved in saline. At the end of the experimental period, blood, and tissue samples were obtained for biochemical and histopathological investigation. Treatment with 0.3 g/kg mulberry flavonoids significantly inhibited the elevated serum glucose (P< 0.01). The increased myelin sheath area (P< 0.01), myelinated fiber cross-sectional area and extramedullary fiber number (P< 0.05) were also reduced in alloxan-induced rats treated with 0.3 g/kg mulberry flavonoids. 0.3 g/kg mulberry flavonoids also markedly decreased onion-bulb type myelin destruction and degenerative changes of mitochondria and Schwann cells. These findings demonstrate that mulberry flavonoids may improve the recovery of a severe peripheral nerve injury in alloxan-induced diabetic rats and is likely to be useful as a potential treatment on peripheral neuropathy (PN) in diabetic rats.

Folhas de amoreira (Morus alba L.) é um medicamento tradicional chinês para a redução da glicose no soro sanguíneo. Avaliaram-se, neste trabalho, os efeitos protetores dos flavonóides de amora no nervo ciático em ratos diabéticos aloxano-induzidos. Dividiram-se 80 ratos Sprague-Dawley em cinco grupos: A (controle), B (diabétidos tratados com solução salina), C-D (diabéticos tratados com 0,3, 0,1 g/kg) e E (diabéticos tratados com 0,3 mg de metilcobal).A diabetes foi induzida por injeção intraperitoneal de 200 mg/kg de aloxana dissolvida em solução salina. No final do período experimental, obtiveram-se amostras de sangue e de tecido para investigação bioquímica e histopatológica. O tratamento com 0,3 g/kg de flavonóides da amoreira inibiu, significativamente, a elevação de glicose no soro (p <0,01). O aumento da área da bainha de mielina (p <0,01), da área de fibra da seção transversal e do número de fibras mielinizadas extramedulares (p <0,05) foi também reduzido em ratos aloxânicos, tratados com 0,3 g/kg flavonóides de amora. Flavonóides da amoreira na dose de 0,3 g/kg também diminuiram, acentuadamente, a destruição da mielina do tipo bulbo de cebola e as alterações degenerativas das células mitocôndrias e das células de Schwann. Estes resultados demonstram que os flavonóides da amoreira podem melhorar a recuperação de uma lesão nervosa periférica grave em ratos com diabetes, induzida por aloxana, e parece ser útil como tratamento potencial para a neuropatia periférica (PN) em ratos diabéticos.

Experimental study on the preventive and treatment function of cortex mori for peripheral nervous lesion at the early stage of diabetes rats / 中国应用生理学杂志

<p><b>AIM</b>To observe the preventive function of cortex mori for peripheral nervous lesion at the early stage in diabetes rats, and probe into the mechanism of that formula.</p><p><b>METHODS</b>Set up the diabetes rat model evoked by alloxan. According to different blood sugar values, randomly divide the rats into normal group, model group, cortex mori(high dosage and low dosage) group and methylcobalamin control group, respectively administer the rats with saline and cortex mori of different dosages by ig (1.875 g/kg, 0.625 g/kg), while 300 microg/kg methylcobalamin for control group, one time each day. Two months after the administration, determine the FBG, body weight, SOD and MDA in blood serum of rats in each group, observe the changes on final product of glycosylation, CGMP and CAMP of sciatic nerve and the synapsin of rats' sciatic nerves. Conduct the pathological observation on area of myelin sheath, extramedullary fiber and the cross section of myelin sheath of sciatic nerves. And observe the changes of ultrafine form of sciatic nerve through transmission electron microscope. In the mean time, determine the MNCV, SNVC and SL, and the tail-flicking test should be undertaken for checking the sensory nerve.</p><p><b>RESULTS</b>Cortex mori can effectively enlarge the area of myelin sheath, extramedullary fiber and the cross section of myelin sheath.</p><p><b>CONCLUSION</b>Cortex mori can obviously ease up the pathological changes of peripheral nerve at the early stage of the diabetes rats, and the overall curative effect is better than that of methylcobalamin.</p>