Jackson,James; Paulose,C S(Department of Biotechnology, May 1, 2000)
[+]
[-]
Abstract:
5-HT2A receptor binding parameters were studied in the cerebral cortex and brain stem of
control, diabetic, insulin, insulin + tryptophan and tr3yptophan treated streptozotocin diabetic
rats. Scatchard analysis using selective antagonist, [-H](±)2,3-dimethoxyphenyl-l-[2-(4-piperidine)-
methanol] ([3H]MDL100907) in cerebral cortex of diabetic rats showed a significant
decrease in dissociation constant (Kd) without any change in maximal binding (Bm). Competition
binding studies in cerebral cortex using ketanserin against [3H]MDL100907 showed
the appearance of an additional site in the low affinity region during diabetes. In the brain
stem, Scatchard analysis showed a significant increase in Bmax and Kd. Displacement studies
showed a shift in the receptor affinity towards a low affinity state. All these altered parameters
in diabetes were reversed to control level by insulin, insulin + tryptophan and tryptophan
treatments. Tryptophan treatment is suggested to reverse the altered 5-HT2Abinding and
blood glucose level to control status by increasing the brain 5-HT content.
Biju,M P; Paulose,C S(Department of Biotechnology, September 27, 1997)
[+]
[-]
Abstract:
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.
Waliaula Mola,P; Sudha, B; Paulose,C S(Department of Biotechnolgy, November , 1996)
[+]
[-]
Abstract:
The effect of insulin on cell proliferation in vivo has been studied in hepatectomised
streptozotocin- diabetic rats. The extent of cell proliferation in sham and hepatectomized- control,
diabetic and insulin treated rats were monitored by determining DNA content and [3H]thymidine
incorporation into DNA. The kinetic parameters of thymidine kinase a regulatory enzyme for
DNA synthesis was also studied in these groups. The rate of DNA synthesis in liver of
streptozotocin -diabetic rats was significantly higher 24 hrs post-hepatectomy compared to
control and insulin treated diabetic groups. Kinetic studies of thymidine kinase revealed that there
was no change in the Michaelis -Menten constant (Km) whereas maximum velocity (Vmax) was
elevated in the diabetic hepatectomized groups compared to control and insulin treated
hepatectomized groups. Thus our study elucidates the role of insulin in thymidine kinase activity
and DNA synthesis.
Seema,P V; Sudha, B; Pius S,Padayatti; Asha,Abraham; Raghu,K G; Paulose,C S(Department of Biotecnology, June , 1996)
[+]
[-]
Abstract:
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.
Jackson,James; Pius S,Padayatti; Thomas,Paul; Paulose,C S(Department of Biotechnology, December 13, 1996)
[+]
[-]
Abstract:
In the present study we assessed plasma and platelet
monoamine content using high performance liquid
chromatography (HPLC). The study included 22 subjects
consisting of 12 freshly-detected male diabetic
patients and 10 age and sex-matched healthy controls.
The same parameters were measured in streptozotocin
-induced diabetic rat models consisting of
controls , diabetic and insulin - treated diabetic rats.
The platelet counts were significantly reduced
(P < 0.05) in rat models as well as human diabetic
samples. The plasma norepinephrine (NE) and epinephrine
(EPI) concentrations were significantly increased
(P < 0.05). The platelet showed a significant
increase (P < 0.01) in NE, EPI and serotonin content.
Increase in the plasma and platelet content of neurotransmitters
may be due to increased sympathetic
function, which is an adaptation for the decreased
platelet count observed in our study . The results indicate
that changes in the neurotransmitter content
of the platelet may be a good index to assess the neurotransmitter
status in pathological condition such as
diabetes mellitus.