A Synthetic Snake-Venom-Based Tripeptide Protects PC12 Cells from the Neurotoxicity of Acrolein by Improving Axonal Plasticity and Bioenergetics.

The synthetic peptide p-BTX-I is based on the native peptide (formed by glutamic acid, valine and tryptophan) isolated from Bothrops atrox venom. We have previously demonstrated its neuroprotective and neurotrophic properties in PC12 cells treated with the dopaminergic neurotoxin 1-methyl-4-phenylpyridinium (MPP+). Now, we have investigated the neuroprotective effects and mechanisms of p-BTX-I against the toxicity of acrolein in PC12 cells. Studies have demonstrated that acrolein might play an important role in the etiology of Alzheimer's disease (AD), which is characterized by neuronal and synaptic loss. Our results showed that not only acrolein reduced cell differentiation and cell viability, but also altered the expression of markers of synaptic communication (synapsin I), energy metabolism (AMPK-α, Sirt I and glucose uptake), and cytoskeleton (ß-III-tubulin). Treatment with p-BTX-I increased the percentage of differentiation in cells treated with acrolein and significantly attenuated cell viability loss, besides counteracting the negative effects of acrolein on synapsin I, AMPK-α, Sirt I, glucose uptake, and ß-III-tubulin. Additionally, p-BTX-I alone increased the expression of apolipoprotein E (apoE) gene, associated with the proteolytic degradation of ß-amyloid peptide aggregates, a hallmark of AD. Taken together, these findings demonstrate that p-BTX-I protects against acrolein-induced neurotoxicity and might be a tool for the development of novel drugs for the treatment of neurodegenerative diseases.

Effects of pregnenolone intervention on the cholinergic system and synaptic protein 1 in aged rats.

OBJECTIVE: To observe the effect of pregnenolone (PREG) intervention on the cholinergic system function and the synaptic protein 1 (SYP1) expression in different brain regions of aged rats. METHOD: Twenty-four-month-old male Sprague Dawley rats intraperitoneally injected every other day for one month were divided into blank control group, solvent control group, PREG (0.5 mg/kg) intervention group and PREG (2.0 mg/kg) intervention group. The rats were sacrificed 2 d after the intervention and the corresponding regions of brain tissue were separated and cryopreserved. Western blot analysis was used to detect the expression level of choline acetyltransferase (ChAT), SYP1, serum PREG and the activity of ChAT and acetylcholinesterase (AChE) in different brain regions. In addition, the semiquantitative changes in the expression level of ChAT and SYP1 in frontal lobe and hippocampus were tested by immunohistochemistry. RESULT: Western blot and immunohistochemistry analysis showed that PREG (2.0 mg/kg) administration led to a significant increase of ChAT and SYP1 expressions in frontal lobe, temporal lobe, and hippocampus regions (p < 0.05). The result of enzyme-linked immunosorbent assay showed that PREG (2.0 mg/kg) administration significantly increased ChAT activity and serum PREG levels and caused a decrease in AChE activity (p < 0.05); while PREG (0.5 mg/kg) only elevated levels of serum PREG. CONCLUSION: PREG significantly improved the synaptic plasticity of memory-related brain areas of aged rats, significantly increased brain cholinergic activity and thus helps to improve learning and memory in aged rats.

Captodiamine, a putative antidepressant, enhances hypothalamic BDNF expression in vivo by synergistic 5-HT2c receptor antagonism and sigma-1 receptor agonism.

The putative antidepressant captodiamine is a 5-HT2c receptor antagonist and agonist at sigma-1 and D3 dopamine receptors, exerts an anti-immobility action in the forced swim paradigm, and enhances dopamine turnover in the frontal cortex. Captodiamine has also been found to ameliorate stress-induced anhedonia, reduce the associated elevations of hypothalamic corticotrophin-releasing factor (CRF) and restore the reductions in hypothalamic BDNF expression. Here we demonstrate chronic administration of captodiamine to have no significant effect on hypothalamic CRF expression through sigma-1 receptor agonism; however, both sigma-1 receptor agonism or 5-HT2c receptor antagonism were necessary to enhance BDNF expression. Regulation of BDNF expression by captodiamine was associated with increased phosphorylation of transcription factor CREB and mediated through sigma-1 receptor agonism but blocked by 5-HT2c receptor antagonism. The existence of two separate signalling pathways was confirmed by immunolocalisation of each receptor to distinct cell populations in the paraventricular nucleus of the hypothalamus. Increased BDNF induced by captodiamine was also associated with enhanced expression of synapsin, but not PSD-95, suggesting induction of long-term structural plasticity between hypothalamic synapses. These unique features of captodiamine may contribute to its ability to ameliorate stress-induced anhedonia as the hypothalamus plays a prominent role in regulating HPA axis activity.

Effect of serum metabolites of Pueraria lobata in rats on peripheral nerve regeneration: in vitro and in vivo studies.

This study provides in vitro and in vivo evaluation of rat serum metabolites of the Pueraria lobata (SMP) on peripheral nerve regeneration. In the in vitro study, we found that the SMP caused a marked enhancement of the nerve growth factor (NGF)-mediated neurite outgrowth and the expression of synapsin I from PC12 cells. In the in vivo study, silicone rubber chambers filled with the SMP were used to bridge a 10-mm sciatic nerve defect in rats. At the conclusion of 8 weeks, animals from the groups treated with the SMP had a relatively more mature structure with larger mean values of myelinated axon number, endoneurial area, and total nerve area when compared with those in the controls receiving the saline only. These results suggest that the serum metabolites of Pueraria lobata can be a potential nerve growth-promoting factor.

Differential distribution of synapsin IIa and IIb mRNAs in various brain structures and the effect of chronic morphine administration on the regional expression of these isoforms.

Quantitative reverse transcriptase-polymerase chain reaction and in situ hybridization techniques were used to determine the regional distribution of synapsin IIa and IIb mRNAs in rat central nervous system and to assess the effect of chronic morphine administration on the gene expression of these two isoforms of synapsin II. These isoforms are members of a family of neuron-specific phosphoproteins thought to be involved in the regulation of neurotransmitter release. Our data demonstrate the widespread distribution, yet regionally variable expression, of synapsin IIa and IIb mRNAs throughout the adult rat brain and spinal cord. The ratios of the relative abundance of synapsins IIa and IIb differed by up to 4.5-fold among the various regions studied. Synapsin IIa and IIb mRNAs were shown to be highly concentrated in the thalamus and in the hippocampus, whereas lower concentrations were found in most other central nervous system structures. In this study, we show differential regulation by morphine of synapsins IIa and IIb in various regions of the brain. In the striatum, a 2.4-fold increase was observed in the levels of synapsin IIa mRNA following chronic morphine regime, whereas no change was found for synapsin IIb. On the other hand, mRNA levels of synapsin IIb in spinal cord of chronically treated rats were markedly decreased (by 62%), while no alterations were observed in synapsin IIa. Selective regulation by morphine has also been demonstrated in several other central nervous system structures. The opiate-induced regulation of the gene expression of synapsin II isoforms could be viewed as one of the cellular adaptations to the persistent opiate effects and may be involved in the molecular mechanism underlying opiate tolerance and/or dependence.