Mohanan,Valiyaveettil; Finla, Chathu; Paulose, Cheramadathikudyil S(Department of Bio Technology, December 1, 2004)
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Abstract:
The purpose of this study was to investigate the role of central 5-HT2C receptor binding in rat model of pancreatic regeneration
using 60-70% pancreatectomy. The 5-HT and 5-HT2c receptor kinetics were studied in cerebral cortex and brain stem of sham
operated, 72 h pancreatectomised and 7 days pancreatectomised rats. Scatchard analysis with [3H] mesulergine in cerebral
cortex showed a significant decrease (p < 0.05) in maximal binding (B^,ax) without any change in Kd in 72 h pancreatectomised
rats compared with sham. The decreased Bmax reversed to sham level by 7 days after pancreatectomy. In brain stem , Scatchard
analysis showed a significant decrease (p < 0.01) in Bax with a significant increase (p < 0.01) in Kd. Competition analysis
in brain stem showed a shift in affinity towards a low affinity. These parameters were reversed to sham level by 7 days after
pancreatectomy. Thus the results suggest that 5-HT through the 5-HT2C receptor in the brain has a functional regulatory role in
the pancreatic regeneration. (Mol Cell Biochem 272: 165-170, 2005)
Jackson,James; Paulose,C S(Department of Biotechnology, November 19, 1998)
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Abstract:
5-Hydroxytryptamine2A (5-HT2A) receptor kinetics was studied in cerebral cortex and brain stem of streptozotocin (STZ) induced
diabetic rats. Scatchard analysis with [3H] (±) 2,3dimethoxyphenyl-l-[2-(4-piperidine)-methanol] ([3H]MDL100907) in cerebral
cortex showed no significant change in maximal binding (Bmax) in diabetic rats compared to controls. Dissociation constant
(K) of diabetic rats showed a significant decrease (p < 0.05) in cerebral cortex, which was reversed to normal by insulin treatment.
Competition studies of [3H]MDL100907 binding in cerebral cortex with ketanserin showed the appearance of an additional
low affinity site for 5-HT2A receptors in diabetic state, which was reversed to control pattern by insulin treatment. In brain stem,
scatchard analysis showed a significant increase (p < 0.05) in Bmax accompanied by a significant increase (p < 0.05) in Kd.
Competition analysis in brain stem also showed a shift in affinity towards a low affinity State for 5-HT2A receptors. All these
parameters were reversed to control level by insulin treatment. These results show that in cerebral cortex there is an increase
in affinity of 5-HT2A receptors without any change in its number and in the case of brain stem there is an increase in number of
5HT2A receptors accompanied by a decrease in its affinity during diabetes. Thus, from the results we suggest that the increase
in affinity of 5-HT2A receptors in cerebral cortex and upregulation of 5-HT2A receptors in brain stem may lead to altered neuronal
function in diabetes.