Pancreastatin inhibitor PSTi8 ameliorates streptozotocin-induced diabetes by suppressing hepatic glucose production.

Elevated plasma glucose concentration, as a consequence of excessive hepatic glucose production, plays a pivotal role in the development of diabetes. A chromogranin A-derived diabetogenic peptide Pancreastatin (PST) enhances hepatic glucose output leading to diabetes. Therefore, here we probed the role of PSTi8, a PST inhibitor in ameliorating diabetes by investigating the effect of high glucose (HG) or PST on glucose metabolism. Further, we also explored the action mechanism of the underlying anti-hyperglycemic effect of PSTi8. PSTi8 treatment rescue cultured L6 and HepG2 cells from HG and PST-induced insulin resistance, respectively. It also enhances insulin receptor kinase activity by interacting with the insulin receptor and enhancing GLUT4 translocation and glucose uptake. Thus, our in-silico and in-vitro data support the PST-dependent and independent activity of PSTi8. Additionally, PSTi8 treatment in streptozotocin-induced diabetic rats improved glucose tolerance by lowering blood glucose and plasma PST levels. Concomitantly, the treated animals exhibited reduced hepatic glucose production accompanied by downregulation of hepatic gluconeogenic genes PEPCK and G6Pase. PSTi8-treated rats also exhibited enhanced hepatic glycogen in line with reduced plasma glucagon concentrations. Consistently, improved plasma insulin levels in PSTi8-treated rats enhanced skeletal muscle glucose disposal via enhanced P-Akt expression. In summary, these findings suggest PSTi8 has anti-hyperglycemic properties with enhanced skeletal muscle glucose disposal and reduced hepatic gluconeogenesis both PST dependent as well as independent.

Vivax malaria: a possible stumbling block for malaria elimination in India.

Plasmodium vivax is geographically the most widely dispersed human malaria parasite species. It has shown resilience and a great deal of adaptability. Genomic studies suggest that P. vivax originated from Asia or Africa and moved to the rest of the world. Although P. vivax is evolutionarily an older species than Plasmodium falciparum, its biology, transmission, pathology, and control still require better elucidation. P. vivax poses problems for malaria elimination because of the ability of a single primary infection to produce multiple relapses over months and years. P. vivax malaria elimination program needs early diagnosis, and prompt and complete radical treatment, which is challenging, to simultaneously exterminate the circulating parasites and dormant hypnozoites lodged in the hepatocytes of the host liver. As prompt surveillance and effective treatments are rolled out, preventing primaquine toxicity in the patients having glucose-6-phosphate dehydrogenase (G6PD) deficiency should be a priority for the vivax elimination program. This review sheds light on the burden of P. vivax, changing epidemiological patterns, the hurdles in elimination efforts, and the essential tools needed not just in India but globally. These tools encompass innovative treatments for eliminating dormant parasites, coping with evolving drug resistance, and the development of potential vaccines against the parasite.

Chondroitin 6-sulfate-binding peptides improve recovery in spinal cord-injured mice.

The role of glycosaminoglycan sulfation patterns, particularly in regard to scar formation and inhibition of neuritogenesis, has been mainly studied in cell culture with a focus on chondroitin 4-sulfate. In this study, we investigated chondroitin 6-sulfate (C6S) and found that it also inhibits neurite outgrowth of mouse cerebellar granule neurons in vitro. To examine whether the inhibitory activity of C6S could be neutralized, seven previously characterized high-affinity C6S-binding peptides were tested, among which three peptides neutralized the inhibitory functions of C6S. We further investigated these peptides in a mouse model of spinal cord injury, since upregulation of C6S expression in the glial scar following injury has been associated with reduced axonal regrowth and functional recovery. We here subjected mice to severe compression injury at thoracic levels T7-T9, immediately followed by inserting gelfoam patches soaked in C6S-binding peptides or in a control peptide. Application of C6S-binding peptides led to functional recovery after injury and prevented fibrotic glial scar formation, as seen by decreased activation of astrocytes and microglia/macrophages. Decreased expression of several lecticans and deposition of fibronectin at the site of injury were also observed. Application of C6S-binding peptides led to axonal regrowth and inhibited the C6S-mediated activation of RhoA/ROCK and decrease of PI3K-Akt-mTOR signaling pathways. Taken together, these results indicate that treatment with C6S-binding peptides improves functional recovery in a mouse model of spinal cord injury.

Adhesion Molecule L1 Agonist Mimetics Protect Against the Pesticide Paraquat-Induced Locomotor Deficits and Biochemical Alterations in Zebrafish.

Besides several endogenous elements, exogenous factors, including exposure to pesticides, have been recognized as putative factors contributing to the onset and development of neurodegenerative diseases, including Parkinson's disease (PD). Considering the availability, success rate, and limitations associated with the current arsenals to fight PD, there is an unmet need for novel therapeutic interventions. Therefore, based on the previously reported beneficial functions of the L1 cell adhesion molecule, we hypothesized that L1 mimetic compounds may serve to neutralize neurotoxicity triggered by the pesticide paraquat (PQ). In this study, we attempt to use PQ for inducing PD-like pathology and the L1 mimetic compounds phenelzine sulfate (PS) and tacrine (TC) as potential candidates for the amelioration of PD symptoms using zebrafish as a model system. Administration of PQ together with the L1 mimetic compounds PS or TC (250 nM) improved survival of zebrafish larvae, protected them from locomotor deficits, and increased their sensorimotor reflexes. Moreover, application of PQ together with PS (500 nM) or TC (1000 nM) in adult zebrafish counteracted PQ-induced toxicity, maintaining normal locomotor functions and spatial memory in an open field and T-maze task, respectively. Both L1 mimetic compounds prevented reduction in tyrosine hydroxylase and dopamine levels, reduced reactive oxygen species (ROS) generation, protected against impairment of mitochondrial viability, improved the antioxidant enzyme system, and prevented a decrease in ATP levels. Altogether, our findings highlight the beneficial functions of the agonistic L1 mimetics PS and TC by improving several vital cell functions against PQ-triggered neurotoxicity.

Knockdown of chondroitin-4-sulfotransferase-1, but not of dermatan-4-sulfotransferase-1, accelerates regeneration of zebrafish after spinal cord injury.

Glycosaminoglycans such as chondroitin sulfate (CS) and dermatan sulfate (DS) are long chains of repeating disaccharide units, covalently linked to core proteins to form proteoglycans. Proteoglycans can be cell membrane-bound or are part of the extracellular matrix. They are important in a wide range of biologic processes, including development, synaptic plasticity, and regeneration after injury, as well as modulation of growth factor signaling, cell migration, survival, and proliferation. Synthesis of CS and DS in the Golgi apparatus is mediated by sulfotransferases that modify sugar chains through transfer of sulfate groups to specific positions on the sugar moieties. To clarify the functions of CS and DS during nervous system regeneration, we studied the effect of chondroitin 4- O-sulfotransferase-1/carbohydrate sulfotransferase-11 (C4ST-1/Chst-11) and dermatan 4- O-sulfotransferase-1/Chst-14 (D4ST-1/Chst-14) down-regulation on spinal cord regeneration in larval and adult zebrafish. In our study, knockdown of C4ST1/Chst-11 accelerated regeneration after spinal cord injury in larval and adult zebrafish and knockdown of D4ST1/Chst-14 did not alter regenerative capacity. From these and previous observations, we drew the conclusion that different CS and DS expression patterns can be growth permitting, growth inhibiting, or neutral for regrowing or sprouting axons, depending on the tissue environment of a particular animal species.-Sahu, S., Li, R., Loers, G., Schachner, M. Knockdown of chondroitin-4-sulfotransferase-1, but not of dermatan-4-sulfotransferase-1, accelerates regeneration of zebrafish after spinal cord injury.

Phenelzine, a small organic compound mimicking the functions of cell adhesion molecule L1, promotes functional recovery after mouse spinal cord injury.

BACKGROUND: Neural cell adhesion molecule L1 contributes to nervous system development and maintenance by promoting neuronal survival, neuritogenesis, axonal regrowth/sprouting, myelination, and synapse formation and plasticity. L1 also enhances recovery after spinal cord injury and ameliorates neurodegenerative processes in experimental rodent models. Aiming for clinical translation of L1 into therapy we screened for and functionally characterized in vitro the small organic molecule phenelzine, which mimics characteristic L1 functions. OBJECTIVE: The present study was designed to evaluate the potential of this compound in vivo in a mouse model of spinal cord injury. METHODS AND RESULTS: In mice, intraperitoneal injection of phenelzine immediately after severe thoracic compression, and thereafter once daily for 6 weeks, improved hind limb function, reduced astrogliosis and promoted axonal regrowth/sprouting at 4 and 5 weeks after spinal cord injury compared to vehicle control-treated mice. Phenelzine application upregulated L1 expression in the spinal cord and stimulated the cognate L1-mediated intracellular signaling cascades in the spinal cord tissue. Phenelzine-treated mice showed decreased levels of pro-inflammatory cytokines, such as interleukin-1ß, interleukin-6, and tumor necrosis factor-α in the injured spinal cord during the acute phase of inflammation. CONCLUSIONS: This study provides new insights into the role of phenelzine in L1-mediated neural functions and modulation of inflammation. The combined results raise hopes that phenelzine may develop into a therapeutic agent for nervous system injuries.

Phenelzine, a cell adhesion molecule L1 mimetic small organic compound, promotes functional recovery and axonal regrowth in spinal cord-injured zebrafish.

Injury to the spinal cord initiates a cascade of cellular and molecular events that contribute to the tissue environment that is non-permissive for cell survival and axonal regrowth/sprouting in the adult mammalian central nervous system. The endogenous repair response is impaired in this generally inhibitory environment. Previous studies indicate that homophilic interactions of the neural cell adhesion molecule L1 (L1CAM) promote recovery after spinal cord injury and ameliorate neurodegenerative processes in experimental rodent and zebrafish models. In light of reports that phenelzine, a small organic compound that mimics L1, stimulates neuronal survival, neuronal migration, neurite outgrowth, and Schwann cell proliferation in vitro in a L1-dependent manner, we examined the restorative potential of phenelzine in a zebrafish model of spinal cord injury. Addition of phenelzine into the aquarium water immediately after spinal cord injury accelerated locomotor recovery and promoted axonal regrowth and remyelination in larval and adult zebrafish. Phenelzine treatment up-regulated the expression and proteolysis of L1.1 (a homolog of the mammalian recognition molecule L1) and phosphorylation of Erk in the spinal cord caudal to lesion site. By combining the results of the present study with those of other studies, we propose that phenelzine bears hopes for therapy of nervous system injuries.

The human natural killer-1 (HNK-1) glycan mimetic ursolic acid promotes functional recovery after spinal cord injury in mouse.

Human natural killer-1 (HNK-1) cell antigen is a glycan epitope involved in several neural events, such as neuritogenesis, myelination, synaptic plasticity and regeneration of the nervous system after injury. We have recently identified the small organic compound ursolic acid (UA) as a HNK-1 mimetic with the aim to test its therapeutic potential in the central nervous system. UA, a plant-derived pentacyclic triterpenoid, is well known for its multiple biological functions, including neuroprotective, antioxidant and anti-inflammatory activities. In the present study, we evaluated its functions in a mouse model of spinal cord injury (SCI) and explored the molecular mechanisms underlying its positive effects. Oral administration of UA to mice 1 h after SCI and thereafter once daily for 6 weeks enhanced the regaining of motor functions and axonal regrowth, and decreased astrogliosis. UA administration decreased levels of proinflammatory markers, including interleukin-6 and tumor necrosis factor-α, in the injured spinal cord at the acute phase of inflammation and activated the mitogen-activated protein kinase and phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin pathways in the injured spinal cord. Taken together, these results suggest that UA may be a candidate for treatment of nervous system injuries.

A Small Organic Compound Mimicking the L1 Cell Adhesion Molecule Promotes Functional Recovery after Spinal Cord Injury in Zebrafish.

Tacrine is a small organic compound that was discovered to mimic the functions of the neural cell adhesion molecule L1 by promoting the cognate functions of L1 in vitro, such as neuronal survival, neuronal migration, neurite outgrowth, and myelination. Based on studies indicating that L1 enhances functional recovery in different central and peripheral nervous system disease paradigms of rodents, it deemed interesting to investigate the beneficial role of tacrine in the attractive zebrafish animal model, by evaluating functional recovery after spinal cord injury. To this aim, larval and adult zebrafish were exposed to tacrine treatment after spinal cord injury and monitored for locomotor recovery and axonal regrowth. Tacrine promoted the rapid recovery of locomotor activities in both larval and adult zebrafish, enhanced regrowth of severed axons and myelination, and reduced astrogliosis in the spinal cords. Tacrine treatment upregulated the expression of L1.1 (a homolog of the mammalian recognition molecule L1) and enhanced the L1.1-mediated intracellular signaling cascades in the injured spinal cords. These observations lead to the hope that, in combination with other therapeutic approaches, this old drug may become a useful reagent to ameliorate the deficits resulting from acute and chronic injuries of the mammalian nervous system.

Resveratrol for prenatal-stress-induced oxidative damage in growing brain and its consequences on survival of neurons.

BACKGROUND: Prenatal-stress-induced neuronal damage in offspring is multifactorial, including oxidative damage in the developing brain. Resveratrol is known to exert its neuroprotective potentials by upregulating several antioxidant systems. Hence, the study was undertaken to evaluate the neuroprotective effect of resveratrol against prenatal-stress-induced hippocampal damage and oxidative damage in neonate rat brains. METHODS: Pregnant rats were subjected to restraint stress during early or late gestational period. Another set of rats received resveratrol during the entire gestational period along with early or late gestational stress. The study parameters included several antioxidant studies directly from rat brain homogenate on the 40th postnatal day and hippocampal neuronal assay on the 21st postnatal day. RESULTS: Early as well as late gestational stress resulted in a significant increase in lipid peroxidation and advanced oxidation protein products and decrease in total antioxidant activity and nitric oxide levels in rat brain homogenate. The neurons of the dentate gyrus were severely affected in early and late gestational stress, and only the neurons of the CA3 region were adversely affected in late gestational stress. Administration of resveratrol reversed the prenatal-stress-induced oxidative damage and neurons of dentate gyrus but not the CA3 hippocampal neurons. CONCLUSIONS: These results show the neuroprotective abilities of resveratrol against prenatal-stress-induced oxidative damage in neonatal rat brain.

Neuroprotective effect of resveratrol against prenatal stress induced cognitive impairment and possible involvement of Na(+), K(+)-ATPase activity.

Resveratrol, an active ingredient of red wine extracts, has been shown to exhibit neuroprotective effects in several experimental models. Hence in the present study, the protective effects of resveratrol on cognitive deficits induced by prenatal stress were evaluated in offspring, and the possible involvement of Na(+), K(+)-ATPase in learning deficits were explored. Pregnant rats were subjected to restraint stress during early or late gestational period. Another set of rats received resveratrol during the entire gestational period along with early or late gestational stress. The study parameters included various behavioral tests like open field test and Morris water maze test. At the end of the behavioral tests (on 40th postnatal day), the offspring were sacrificed, and their brain homogenate was subjected to Na(+), K(+)-ATPase estimation. Early and late gestational stress affected spatial learning and memory and prenatal resveratrol has reversed these cognitive deficits. The Na(+), K(+)-ATPase activity in the offspring brain homogenate was reduced in the late gestational stress group; however prenatal resveratrol treatment has not affected this activity. These data suggest the neuroprotective efficacy of resveratrol against prenatal stress induced cognitive impairment. Though late gestational stress involves Na(+), K(+)-ATPase activity in rat brain homogenate, this would not be the primary cause in prenatal stress-induced cognitive dysfunction.

Effect of prenatal stress on expression of glutathione system in neonatal rat brain.

AIM: Prenatal stress is known to adversely affect the fetal brain development and also neuronal loss. The mechanism(s) associated with prenatal stress induced developmental neurotoxicity remains obscure. Few studies point to the glutathione (GSH) antioxidant system which is an important molecular target for this toxicant. Hence the present study investigates the effect of prenatal stress on glutathione system in neonatal rat brain. MATERIAL AND METHODS: Three to four months old pregnant Wistar rats were subjected to restraint stress during early or late gestational period. The offspring were sacrificed on 40th day and their brain homogenate was subjected to antioxidant studies. The serum corticosterone and adrenal ascorbic acid levels were also estimated from offspring. RESULTS: The prenatal stress has resulted in an increase in the serum corticosterone and reduced adrenal ascorbic acid levels in neonatal pups. Prenatal stress during early or late gestation life showed reduced glutathione, glutathione reductase (GSSG-Rd) and superoxide dismutase (SOD) activity in offspring brain homogenate. CONCLUSION: These data suggest that stress during early or late gestation period affect glutathione system in developing neonatal rat brain, which is associated with elevated serum corticosterone and reduced adrenal ascorbic acid levels.