Kinetic Studies of Purified malate Dehydrogenase in Liver of Streptozotocindiabetic Rats and the Effect of Leaf Extract of Aegle Marmelose (L.) Correa ex Roxb

The functional basis of diabetes-mellitus to a certain extent, can be elucidated by studying diabetes-induced changes in metabolic enzymes. Malate dehydrogenase (MDH), is an enzyme directly involved in glucose metabolism. The kinetic parameters of MDH and its purified cytosolic isozyme, S-MDH, have been studied in the liver of streptozotocin- diabetic rats; also the potential of the leaf extract of A. marmelose as an was investigated. The Km of the liver enzyme increased significantly, in both crude and purified preparations in the diabetic state when compared to Lhe respective controls. Insulin as well as leaf- •extract treatment of the diabetic rats brought about a reversal of K. values to near normal. Vmax of purified S-MDH was significantly higher in the diabetic state when compared to the control. Insulin and leaf extract treatment did not reverse this change. Since MDH is an important enzyme in glucose metabolism, the variation in its quantitative and qualitative nature may contribute to the pathological status of diabetes. The fact that leaf extract of A. marmelose was found to be as effective as insulin in restoration of blood glucose and body weight to normal levels, the use of A. marmelose as potential hypoglycemic agent is suggested.

Brain Glutamate Dehydrogenase Changes In Streptozotocin Diabetic Rats As A Function Of Age

Kinetic parameters of brain glutamate dehydrogenase (GDH) were compared in the brain stem, cerebellum and cerebral cortex of three weeks and one year old streptozotocin (STZ) induced four day diabetic rats with respective controls. A single intrafemoral dose of STZ (60mg/Kg body weight) was administered to induce diabetes in both age groups. After four days the blood glucose levels showed a significant increase in the diabetic animals of both age groups compared with the respective controls. The increase in blood glucose was significant in one year old compared to the three weeks old diabetic rats. The Vmm of the enzyme was decreased in all the brain regions studied, of the three weeks old diabetic rats without any significant change in the Km. In the adult the Vmax of GDH was increased in cerebellum and brain stem but was unchanged in the cerebral cortex. The K. was unchanged in cerebellum and cerebral cortex but was increased in the brain stem. These results suggest there may be an important regulatory role of the glutamate pathway in brain neural network disturbances and neuronal degeneration in diabetes as a function of age.

Dopaminergic Regulation of Glucose-induced Insulin Secretion through Dopamine D2 Receptors in the Pancreatic Islets In Vitro

The stimulatory effect of dopamine through dopamine 1)2 receptor on glucose - induced insulin secretion was studied in the pancreatic islets in nitro. I)oparnilie signifieanlly stimula(ed insulin secretion at a concentration of 10 a N1 in the presence of high,glucose ( 20 nii1 ). ' fhe higher concentrations of dopamine (111 -1() 4) inhibited glucose- induced insulin secretion in the presence of both 4 mM1 and 20 m M glucose. Stimulatory and inhibitory effect of dopamine on glucose - induced insulin secretion was reverted by the addition of dopamine 1)2 receptor antagonists such as butaclamol and sulpiride . Norepinephrine (NE) at 111 4 11 concentration inhibited the dopamine uptake as well as its stimulatory effect at 11) - 8 IN1 concentration on glucose induced insulin secretion. Our results suggest that dopamine exerts a differential effect on glucose -induced insulin secretion through dopamine D2 receptor and it is essential for the regulation of glucose-induced insulin secretion by pancreatic islets.

Decreased GABAA Receptors Functional Regulation 3 in the Cerebral Cortex and Brainstem of Hypoxic Neonatal Rats: 4 Effect of Glucose and Oxygen Supplementation

Hypoxia in neonates can lead to biochemical and molecular alterations mediated through changes in neurotransmitters resulting in permanent damage to brain. In this study, we evaluated the changes in the receptor status of GABAA in the cerebral cortex and brainstem of hypoxic neonatal rats and hypoxic rats supplemented with glucose and oxygen using binding assays and gene expression of GABAAa1 and GABAAc5. In the cerebral cortex and brainstem of hypoxic neonatal rats, a significant decrease in GABAA receptors was observed, which accounts for the respiratory inhibition. Hypoxic rats sup- plemented with glucose alone and with glucose and oxygen showed, respectively, a reversal of the GABAA receptors, andGABAAa1 and GABAAc5 gene expression to control. Glucose acts as an immediate energy source thereby reducing the ATP-depletion-induced increase in GABA and oxygenation, which helps in encountering anoxia. Resuscitation with oxygen alone was less effective in reversing the receptor alterations. Thus, the results of this study suggest that reduction in the GABAA receptors functional regulation during hypoxia plays an important role in mediating the brain damage. Glucose alone and glucose and oxygen supplementation to hypoxic neonatal rats helps in protecting the brain from severe hypoxic damage.

Dopamine D1 and D2 Receptor Gene Expression and cGMP, IP3 and Ca2+ Regulation in the Brain Regions of Hypoxic Neonatal Rats: Role of Glucose, Oxygen and Epinephrine Supplementation

Department of Biotechnology, Cochin University of Science and Technology

GABA, serotonin, muscarinic receptors - their second messengers and transcription factors functional regulation in the brain regions of hypoxic neonatal rats: Resuscitation with glucose, oxygen and epinephrine

The present study was designed to investigate the protective effect of glucose, oxygen and epinephrine resuscitation on impairment in the functional role of GABAergic, serotonergic, muscarinic receptors, PLC, BAX, SOD, CAT and GPx expression in the brain regions of hypoxia induced neonatal rats. Also, the role of hormones - Triiodothyronine (T3) and insulin, second messengers – cAMP, cGMP and IP3 and transcription factors – HIF and CREB in the regulation of neonatal hypoxia and its resuscitation methods were studied. Behavioural studies were conducted to evaluate the motor function and cognitive deficit in one month old control and experimental rats. The efficient and timely supplementation of glucose plays a crucial role in correcting the molecular changes due to hypoxia, oxygen and epinephrine. The sequence of glucose, epinephrine and oxygen administration at the molecular level is an important aspect of the study. The additive neuronal damage effect due to oxygen and epinephrine treatment is another important observation. The corrective measures by initial supply of glucose to hypoxic neonatal rats showed from the molecular study when brought to practice will lead to healthy intellectual capacity during the later developmental stages, which has immense clinical significance in neonatal care.

Adrenergic and Glutamergic Receptor Gene Expression and Their Functional regulation in the Cerebral Cortex of Hypoxia Induced Neonatal Rats:Role of Oxygen,Epinephrine and Glucose Supplementation

In the present work, the role of oxygen, epinephrine and glucose supplementation in regulating neurotransmitter contents, adrenergic and glutamate receptor binding parameters in the cerebral cortex of experimental groups of neonatal rats were investigated. The study of neurotransmitters and their receptors in the cerebral cortex and the EEG pattern in the brain regions of neonatal rats were taken as index for brain damage due to hypoxia, oxygen and epinephrine. Real-Time PCR work was done to confirm the binding parameters. Second messenger, cyclic Adenosine Monophosphate (cAMP) was assayed to find the functional correlation of the receptors. Behavioural studies were carried out to confirm the biochemical and molecular studies. The efficient and timely supplementation of glucose plays a crucial role in correcting the molecular changes due to hypoxia, oxygen and epinephrine. The addictive neuronal damage effect due to oxygen and epinephrine treatment is another important observation. The corrective measures from the molecular study brought to practice will lead to maintain healthy intellectual capacity during the later developmental stages, which has immense clinical significance in neonatal care.

Dopamine D2 and 5-HT2A receptor gene expression

Neuronal dopamine and serotonin receptors are widely distributed in the central and the peripheral nervous systems at different levels. Dopaminergic and serotonergic systems have crucial role in aldehyde dehydrogenase regulation Stimulation of autonomic nervous system during ethanol treatment is suggested to be an important factor in regulating the ALDH function. The ALDH enzyme activity was increased in plasma, cerebral cortex, and liver but decreased in cerebellum. The ALDH enzyme affinity was decreased in plasma, brainstem and liver and increased in cerebral cortex and cerebellum. Dopamine and serotonin content decreased in liver and brain regions - cerebral cortex, corpus striatum of ethanol treated rats with an increased HVA/DA, 5-HIAA/5-HT tumover rate. Dopamine content decreased in brainstem with an increased HVA/DA turnover rate and serotonin content decreased with an increased 5-HIAA/5-HT turnover rate in the brainstem of ethanol treated rats compared to control. Serotonin content increased in hypothalamus with a decreased 5-HIAA/5—HT turnover rate where as dopamine content decreased in hypothalamus with an increased HVA/DA tumover rate of ethanol treated rats compared to control.alterations of DA D2 and 5-HTQA receptor function and gene expression in the cerebellum, hypothalamus, corpus striatum, cerebral cortex play an important role in the sympathetic regulation of ALDH enzyme in ethanol addiction. There is a serotonergic and dopaminergic functional regulation of ALDH activity in the brain regions and liver of ethanol treated rats. Gene expression studies of DA D2 and 5'HT2A studies confirm these observations. Perfusion studies using DA, 5-HT and glucose showed ALDH regulatory function. Brain activity measeurement using EEG showed a prominentfrontal brain wave difference. This will have immense clinical significance in the management of ethanol addiction.

“Studies on glucose tolerant β-glucosidases from a novel Byssochlamys fulva and their applications in biomass to ethanol conversion”

Beta-glucosidases are critical enzymes in biomass hydrolysis process and is important in creating highly efficient enzyme cocktails for the bio-ethanol industry. Among the two strategies proposed for overcoming the glucose inhibition of commercial cellulases, one is to use heavy dose of BGL in the enzyme blends and the second is to do simultaneous saccharification and fermentation where glucose is converted to alcohol as soon as it is being generated. While the former needs extremely high quantities of enzyme, the latter is inefficient since the conditions for hydrolysis and fermentation are different. This makes the process technically challenging and also in this case, the alcohol generation is lesser, making its recovery difficult. A third option is to use glucose tolerant β-glucosidases which can work at elevated glucose concentrations. However, there are very few reports on such enzymes from microbial sources especially filamentous fungi which can be cultivated on cheap biomass as raw material. There has been very less number of studies directed at this, though there is every possibility that filamentous fungi that are efficient degraders of biomass may harbor such enzymes. The study therefore aimed at isolating a fungus capable of secreting glucose tolerant β- glucosidase enzyme. Production, characterization of β-glucosidases and application of BGL for bioethanol production were attempted.

Dopamine receptor subtypes functional regulation in insulin induced hypoglycemic neonatal rats: Effect of Glucose, Bacopa monnieri and Bacoside A resuscitation

In the present work we studied the potential of Bacopa monnieri and Bacoside A treatment to enhance the antioxidant system and support the neuronal survival in the hypoglycemic neonatal brain. For achieving the aim, DAD1 and DAD2 receptors functional regulation, gene expression of growth factors, neuronal survival and apoptotic factors during insulin induced hypoglycemic neonatal brain in rats were studied.