Electroacupuncture facilitates the integration of a grafted TrkC-modified mesenchymal stem cell-derived neural network into transected spinal cord in rats via increasing neurotrophin-3.

AIMS: This study was aimed to investigate whether electroacupuncture (EA) would increase the secretion of neurotrophin-3 (NT-3) from injured spinal cord tissue, and, if so, whether the increased NT-3 would promote the survival, differentiation, and migration of grafted tyrosine kinase C (TrkC)-modified mesenchymal stem cell (MSC)-derived neural network cells. We next sought to determine if the latter would integrate with the host spinal cord neural circuit to improve the neurological function of injured spinal cord. METHODS: After NT-3-modified Schwann cells (SCs) and TrkC-modified MSCs were co-cultured in a gelatin sponge scaffold for 14 days, the MSCs differentiated into neuron-like cells that formed a MSC-derived neural network (MN) implant. On this basis, we combined the MN implantation with EA in a rat model of spinal cord injury (SCI) and performed immunohistochemical staining, neural tracing, electrophysiology, and behavioral testing after 8 weeks. RESULTS: Electroacupuncture application enhanced the production of endogenous NT-3 in damaged spinal cord tissues. The increase in local NT-3 production promoted the survival, migration, and maintenance of the grafted MN, which expressed NT-3 high-affinity TrkC. The combination of MN implantation and EA application improved cortical motor-evoked potential relay and facilitated the locomotor performance of the paralyzed hindlimb compared with those of controls. These results suggest that the MN was better integrated into the host spinal cord neural network after EA treatment compared with control treatment. CONCLUSIONS: Electroacupuncture as an adjuvant therapy for TrkC-modified MSC-derived MN, acted by increasing the local production of NT-3, which accelerated neural network reconstruction and restoration of spinal cord function following SCI.

Hyperbaric oxygen preserves neurotrophic activity of carbon monoxide-exposed astrocytes.

In astrocytes, carbon monoxide (CO) poisoning causes oxidative stress and mitochondrial dysfunction accompanied by caspase and calpain activation. Impairment in astrocyte function can be time-dependently reduced by hyperbaric (3bar) oxygen (HBO). Due to the central role of astrocytes in maintaining neuronal function by offering neurotrophic support we investigated the hypothesis that HBO therapy may exert beneficial effect on acute CO poisoning-induced impairment in intrinsic neurotrophic activity. Exposure to 3000ppm CO in air followed by 24-72h of normoxia caused a progressive decline of gene expression, synthesis and secretion of nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) to different extent. 1h treatment with 100% oxygen disclosed a pressure- and time-dependent efficacy in preserving astrocytic neurotrophic support. The beneficial effect was most evident when the astrocytes were exposed to HBO 1-5h after exposure to CO. The results further support an active role of hyperbaric, not normobaric, oxygenation in reducing dysfunction of astrocytes after acute CO poisoning. By preserving endogenous neurotrophic activity HBO therapy might promote neuronal protection and thus prevent the occurrence of late neuropsychological sequelae.

Herbal formula SYJN increases neurotrophin-3 and nerve growth factor expression in brain regions of rats exposed to chronic unpredictable stress.

AIM OF THE STUDY: SYJN is a Chinese herbal formula that contains four herbs: Bupleurum chinense DC., Curcuma aromatica Salisb., Perilla frutescens (L.) Britt., and Acorus tatarinowii Schott. Previous studies conducted in our laboratory have revealed an antidepressant-like effect of the formula in chronic unpredictable stress (CUS)-induced depression model in rats. The present study aimed to investigate whether neurotrophin-3 (NT-3) and nerve growth factor (NGF) are involved in the antidepressant-like action of SYJN by using the same depressive model in rats. MATERIALS AND METHODS: Rats were subjected to an experimental setting of CUS. The mechanism underlying the antidepressant-like action of SYJN was examined by measuring protein and mRNA expression of NT-3 and NGF in brain tissues of CUS-exposed rats. RESULTS: The results showed that NT-3 protein and mRNA expression in the hippocampus and frontal cortex were significantly decreased in CUS-treated rats. CUS treatment also significantly decreased NGF protein and mRNA expression in the frontal cortex of the animals. Daily intragastric administration of SYJN (1300 or 2600 mg/kg/day) during the 4 weeks of CUS significantly suppressed these changes induced by CUS. CONCLUSION: The results suggest that the antidepressant-like activity of SYJN is likely mediated by the increases in NT-3 and NGF expression in brain tissues.

Renoprotective effect of total glucosides of paeony (TGP) and its mechanism in experimental diabetes.

Total glucosides of paeony (TGP), extracted from the root of Paeonia lactiflora pall, has been shown to have ant-inflammatory and antioxidative actions. The aims of this study were to elucidate the renoprotective effect of TGP and its mechanism in experimental diabetes. Streptozotocin-induced diabetic rats were treated with TGP for 8 weeks. Treatment with TGP at 50, 100, and 200 mg/kg significantly lowered 24-h urinary albumin excretion rate in diabetic rats. TGP treatment in all doses markedly attenuated glomerular volume, and treatment with TGP at 100 and 200 mg/kg markedly reduced indices for tubulointerstitial injury in diabetic rats. Western blot analysis showed that the expressions of 1 alpha (IV) collagen, intercellular adhesion molecule (ICAM)-1, interleukin (IL)-1, tumor necrosis factor (TNF)-alpha, NF-kappaB p65, and 3-nitrotyrosine (3-NT) protein were increased in the kidneys of diabetic rats; the increases in these proteins were all dose-dependently and significantly inhibited by TGP treatment. The expression of nephrin protein was significantly reduced in the kidneys from diabetic rats and markedly increased by TGP treatment. The expression of transforming growth factor (TGF)-beta1 protein in the kidney was also significantly increased in diabetic rats, which was significantly inhibited by treatment with TGP at all doses. Our data suggest that TGP treatment ameliorates early renal injury via the inhibition of expression of ICAM-1, IL-1, TNF-alpha, and 3-NT in the kidneys of diabetic rats.

Differential expression of neurotrophins in penises of streptozotocin-induced diabetic rats.

To explore the mechanism of diabetic erectile dysfunction, we studied the distribution of neurotrophins in the penises of diabetic rats, including nerve growth factor (NGF), brain derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and neurotrophin-4 (NT-4). Male Sprague-Dawley rats were injected with 65 mg/kg streptozotocin to induce diabetes mellitus (DM). The control rats were raised as age-matched control. Eight weeks later, the intercavernous pressure (ICP) of the rats was measured after electrostimulation and before sacrifice. Each peeled penis was divided into 2 parts, one for immunohistochemistry and the other for Western blot analysis. The ICP of the DM group rats was significantly decreased as compared to the vehicle control rats. There were significantly more NGF-positive neurons in the penises of the diabetic rats than in those of the control rats, while the opposite results were observed for BDNF-positive neurons. In the Western blot analysis, the proteins of NGF, NT-3, and NT-4 were all increased, while that of BDNF was decreased in diabetic rats. This is the first study revealing the expression of NT-4 protein in cavernous tissue. The abnormal level of these 4 neurotrophins in cavernous tissue may be one of the factors of the pathogenesis of diabetic ED. The increase of neurotrophins may reflect the degree of cavernous tissue denervation and may represent a compensatory mechanism. The lesion of the retrograde axonal transport of the nerves caused by hyperglycemia may be related to this phenomenon.

Neurotrophin-3 is a target-derived neurotrophic factor for penile erection-inducing neurons.

The aim of this study was to determine whether the neurotrophins nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and neurotrophin (NT)-3 could act as endogenous target-derived trophic factors for erection-inducing, i.e. penis-projecting major pelvic ganglion (MPG) neurons, and/or penile sensory neurons in adult rat. This was accomplished by studying the expression of NT mRNAs in the penis and their cognate receptors in the MPG and dorsal root ganglia (DRGs), and the retrograde axonal transport of radioiodinated NTs injected into the corpora cavernosa. Northern hybridization showed that NGF, BDNF, and NT-3 mRNAs are expressed in the shaft of the penis. In situ hybridization combined with usage of the retrograde tracer Fluoro-Gold showed that TrkC and p75 receptors are expressed in penis-projecting neurons of the MPG whereas the mRNAs for TrkA and TrkB receptors were undetectable. However, all the NT receptor mRNAs were expressed in penile sensory neurons of sacral level 1 (S1) DRG. (125)I-NT-3 injected into the shaft of the penis was retrogradely transported into the MPG and S1 DRG, whereas radioiodinated NGF and BDNF were transported specifically into the S1 DRG, thus confirming the existence of functional NT receptors in these penile neurons. In conclusion, these data suggest that NT-3 may act as a target-derived neurotrophic factor for both erection-inducing and penile sensory neurons, whereas NGF and BDNF may be more important for the sensory innervation of the penis.

[Effect of acupuncture on the expression of NT3 in the process of spinal plasticity].

OBJECTIVE: To explore the change in the expression of NT3 in the process of promoting the plasticity of spinal cord by acupuncture. METHODS: Five adult cats were subjected to unilateral spared root rhizotomy; their L1-L5, L7-S2 dorsal root ganglia (DRG) were sectioned, but L4 was spared. And two groups of acupoints [Zusani (St.36) and Xuanzhong (G. B.39); Futu (St.32) and Sanyingjiao (Sp.6)] located in hind limb were electro-stimulated for thirty minutes q.d. x 7. At seven days, after acupuncture, the L5 segment of spinal cord and spared dorsal root ganglion (L6) were taken and made into frozen section 20 microns in thickness. Immunohistochemistry (NT3 antibody 1:1500) and in situ hybridization (NT3 cRNA probe 1:100) techniques were used. The numbers of positive neuron for NT3 and it's mRNA in large, medium, small neuron of L6 DRG and the numbers of positive neurons and glia cells for NT3 in lamina II were counted respectively. RESULTS: The numbers of positive large, small neurons for NT3 and its mRNA in DRG and the number of positive neurons and glia cells for NT3 in lamina II on the acupuncture side increased apparently than those on the non-acupuncture side (P < 0.05). However, the positive signal of NT3 mRNA in lamina II was not seen in our study. CONCLUSION: The results indicate that acupuncture promoting the plasticity of spinal cord involves both the increase in expression of NT3 in large and small neurons of spared DRG and the increase in number of NT3 positive neurons and glia cells in spinal lamina II. Moreover, NT3 may play a role in the process of promoting the plasticity of spinal cord by acupuncture.