Jackson,James; Paulose,C S(Department of Biotechnology, May 1, 2000)
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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; Pyroja,Sulaiman; Rajeshkumar,Neelimmathara V; Paulose,C S(Department of Biotechnology, September 20, 2000)
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Abstract:
GABAergic alterations in hypothalamus during compensatory hyperplasia after partial hepatectomy (PH), lead nitrate (LN)
induced direct hyperplasia and N-nitrosodiethylamine (NDEA) induced neoplasia in liver were investigated. Serum GABA
levels were increased in all 3 experimental groups compared with the control. GABA content decreased in hypothalamus of
PH and NDEA treated rats, while it increased in LN treated rats. GABAA receptor number and affinity in hypothalamic membrane
preparations of rats showed a significant decrease in PH and NDEA treated rats, while in LN treated rats the affinity
increased without any change in the receptor number. The GABAB receptor number increased in PH and NDEA treated rats,
while it decreased in LN treated rats. The affinity of the receptor also increased in NDEA treated rats. Plasma NE levels
showed significant increase in PH and NDEA rats compared with the control while it decreased in LN treated rats. The results
of the present study suggests that liver cell proliferation is influencing the hypothalamic GABAergic neurotransmission
and these changes regulate the hepatic proliferation through the sympathetic stimulation.