Decreased 5-HT2C receptor binding in the cerebral cortex and brain stem during pancreatic regeneration in rats

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)

Decreased (x1-Adrenergic Receptor Binding in the Cerebral Cortex and Brain Stem during Pancreatic Regeneration in Rats

purpose of this study was to investigate the role of brain al-adrenergic receptor binding in the rat model of pancreatic regeneration using 60-70% pancre:dectorny. The a, -adrenergic receptors kinetics was studied in the cerebral cor:cx and brain stem of sham operated . 72 It pan- crea(ectoinised and 7 days pancreatectomised rats. Scar chard analysis with I `I I lprazocin in cerebral cartes and brain stein showed a significant decrease (/' < 0.01). (P < 0.05) in maximal binding ( 1),,,,,) with it significant decrease (P < 0.001 ), ( P < 0.01) in the K,,in 72 It pancreatecto- raised rats compared with sham , respectively . Competition analysis in cerebral cortex and brain stem showed it shift in affinity during pancreatic regeneration . The sympathetic activity was decreased as indicated by the significantly de- increased norepinephrine level in the plasma (P < 0.001), cerebral cortex (P < 0.01) and brain stem (P < 0.001) of 72 h pancreatectomised rats compared to sham . Thus, from our results it is suggested that the central a, -adrenergic receptors have a functional role in the pancreatic regenera- Lion mediated through the sympathetic pathway.

Increased 5-HT2C Receptor Binding in the Brain Stem And Cerebral Cortex During Liver Regeneration And Hepatic Neoplasia In Rats

In the present study, serotonin 2C (5-HT2c) receptor binding parameters in the brainstem and cerebral cortex were investigated during liver generation after partial hepatectomy (PH) and N-nitrosodiethylamine (NDEA) induced hepatic neoplasia in male Wistar rats. The serotonin content increased significantly (p<0.01) in the cerebral cortex after PH and in NDEA induced hepatic neoplasia. Brain stem serotonin content increased significantly (p<0.05) after PH and (p<0.001) in NDEA induced hepatic neoplasia. The number and affinity of the 5-HT2c receptors in the crude synaptic membrane preparations of the brain stem showed a significant (p<0.001) increase after PH and in NDEA induced hepatic neoplasia. The number and affinity of 5-HT2c receptors increased significantly (p<0.001) in NDEA induced hepatic neoplasia in the crude synaptic membrane preparations of the cerebral cortex. There was a significant (p<0.01) increase in plasma norepinephrine in PH and (p<0.001) in NDEA induced hepatic neoplasia, indicating sympathetic stimulation. Thus, our results suggest that during active hepatocyte proliferation 5-HT2c receptor in the brain stem and cerebral cortex are up-regulated which in turn induce hepatocyte proliferation mediated through sympathetic stimulation.

Decreased [ 3 H] YM-09151-2 binding to dopamine D2 receptors in the hypothalamus, brainstem and pancreatic islets of streptozotocin -induced diabetic rats

In the present study dopamine was measured in the hypothalamus, brainstem, pancreatic islets and plasma, using HPLC. Dopamine D2 receptor changes in the hypothalamus, brainstem and pancreatic islets were studied using [3H] YM-09151-2 in streptozotocin-induced diabetic and insulintreated diabetic rats. There was a significant decrease in dopatnine content in the hypothalamus (P<0.001), brainstem (P<0.001), pancreatic islets (P<0.001) and plasma (P<0.00I) in diabetic rats when compared to control. Scatchard analysis of [3H] YM-09151-2 in the hypothalamus of diabetic rats showed a significant decrease in Bax (P<0.001) and Kd, showing an increased affinity of D2 receptors when compared to control. Insulin treatment did not completely reverse the changes that occurred during diabetes. There was a significant decrease in B,nax (P<0.01) with decreased affinity in the brainstem of diabetic rats. The islet membrane preparation of diabetic rats showed a significant decrease (P<0.001) in the binding of [3H] YM-09 151-2 with decreased Kd (P<0.001) compared to control. The increase in affinity of D2 receptors in hypothalamus and pancreatic islets and the decreased affinity in brainstem were confirmed by competition analysis. Thus our results suggest that the decreased dopamine D, receptor function in the hypothalamus, brainstem and pancreas affects insulin secretion in diabetic rats, which has immense clinical relevance to the management of diabetes.

Enhancement of [m-methoxy 3H]MDL100907 binding to 5HT 2A receptors in cerebral cortex and brain stem of streptozotocin induced diabetic rats

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.

Enhancement Of High Affinity Y-Aminobutyric Acid Receptor Binding In Cerebellum Of Pyridoxine-Deficient Rat

The high-affinity of [3H]y-aminobutyric acid (GABA) to GABAA receptors and [3H]baclofen to GABAB receptors were studied in the cerebellum of pyridoxine-deficient rats and compared to pyridoxine-supplemented controls. There was a significant increase in the maximal binding ( Bmax) of both GABAA and GABAB receptors with no significant difference in their binding affinities (Kd). The changes observed suggest a supersensitivity of GABAA and GABAB receptors which seems to correlate negatively with the concentration of GABA in the cerebellum of pyridoxine-deficient rats.

Spray Pyrolysed Zinc Oxide Thin Films : Effects of Doping and Ion Beam Irradiation

In recent years scientists have made rapid and significant advances in the field of semiconductor physics. One of the most important fields of current interest in materials science is the fundamental aspects and applications of conducting transparent oxide thin films (TCO). The characteristic properties of such coatings are low electrical resistivity and high transparency in the visible region. The first semitransparent and electrically conducting CdO film was reported as early as in 1907 [1]. Though early work on these films was performed out of purely scientific interest, substantial technological advances in such films were made after 1940. The technological interest in the study of transparent semiconducting films was generated mainly due to the potential applications of these materials both in industry and research. Such films demonstrated their utility as transparent electrical heaters for windscreens in the aircraft industry. However, during the last decade, these conducting transparent films have been widely used in a variety of other applications such as gas sensors [2], solar cells [3], heat reflectors [4], light emitting devices [5] and laser damage resistant coatings in high power laser technology [6]. Just a few materials dominate the current TCO industry and the two dominant markets for TCO’s are in architectural applications and flat panel displays. The architectural use of TCO is for energy efficient windows. Fluorine doped tin oxide (FTO), deposited using a pyrolysis process is the TCO usually finds maximum application. SnO2 also finds application ad coatings for windows, which are efficient in preventing radiative heat loss, due to low emissivity (0.16). Pyrolitic tin oxide is used in PV modules, touch screens and plasma displays. However indium tin oxide (ITO) is mostly used in the majority of flat panel display (FPD) applications. In FPDs, the basic function of ITO is as transparent electrodes. The volume of FPD’s produced, and hence the volume of ITO coatings produced, continues to grow rapidly. But the current increase in the cost of indium and the scarcity of this material created the difficulty in obtaining low cost TCOs. Hence search for alternative TCO materials has been a topic of active research for the last few decades. This resulted in the development of binary materials like ZnO, SnO2, CdO and ternary materials like II Zn2SnO4, CdSb2O6:Y, ZnSO3, GaInO3 etc. The use of multicomponent oxide materials makes it possible to have TCO films suitable for specialized applications because by altering their chemical compositions, one can control the electrical, optical, chemical and physical properties. But the advantages of using binary materials are the easiness to control the chemical compositions and depositions conditions. Recently, there were reports claiming the deposition of CdO:In films with a resistivity of the order of 10-5 ohm cm for flat panel displays and solar cells. However they find limited use because of Cd-Toxicity. In this regard, ZnO films developed in 1980s, are very useful as these use Zn, an abundant, inexpensive and nontoxic material. Resistivity of this material is still not very low, but can be reduced through doping with group-III elements like In, Al or Ga or with F [6]. Hence there is a great interest in ZnO as an alternative of ITO. In the present study, we prepared and characterized transparent and conducting ZnO thin films, using a cost effective technique viz Chemical Spray Pyrolysis (CSP). This technique is also suitable for large area film deposition. It involves spraying a solution, (usually aqueous) containing soluble salts of the constituents of the desired compound, onto a heated substrate.

Optical and electrical properties of amorphous zinc tin oxide thin films examined for thin film transistor application

Structural, electronic, and optical properties of amorphous and transparent zinc tin oxide films deposited on glass substrates by pulsed laser deposition (PLD) were examined for two chemical compositions of Zn:Sn=1:1 and 2:1 as a function of oxygen partial pressure PO2 used for the film deposition and annealing temperature. Different from a previous report on sputter-deposited films Chiang et al., Appl. Phys. Lett. 86, 013503 2005 , the PLD-deposited films crystallized at a lower temperature 450 °C to give crystalline ZnO and SnO2 phases. The optical band gaps Tauc gaps were 2.80−2.85 eV and almost independent of oxygen PO2 , which are smaller than those of the corresponding crystals 3.35−3.89 eV . Films deposited at low PO2 showed significant subgap absorptions, which were reduced by postthermal annealing. Hall mobility showed steep increases when carrier concentration exceeded threshold values and the threshold value depended on the film chemical composition. The films deposited at low PO2 2 Pa had low carrier concentrations. It is thought that the low PO2 produced high-density oxygen deficiencies and generated electrons, but these electrons were trapped in localized states, which would be observed as the subgap absorptions. Similar effects were observed for 600 °C crystallized films and their resistivities were increased by formation of subgap states due to the reducing high-temperature condition. High carrier concentrations and large mobilities were obtained in an intermediate PO2 region for the as-deposited films.

Optical emission spectroscopic studies on laser ablated zinc oxide plasma

Optical emission spectroscopic studies were carried out on the plasma produced by ablation of zinc oxide target using the third harmonic 355 nm of Q-switched Nd:YAG laser, in vacuum and at three different ambient gas oxygen pressures. The spatial variations of electron density Ne and electron temperature Te were studied up to a distance of 20 mm from the target surface. The kinematics of the emitted particles and the expansion of the plume edge are discussed. The optimum conditions favorable for the formation of high quality zinc oxide thin films are thereby suggested.

Growth of zinc oxide thin films for optoelectronic application by pulsed laser deposition

Zinc oxide (ZnO) thin films were deposited on quartz, silicon, and polymer substrates by pulsed laser deposition (PLD) technique at different oxygen partial pressures (0.007 mbar to 0.003 mbar). Polycrystalline ZnO films were obtained at room temperature when the oxygen pressure was between 0.003 mbar and .007 mbar, above and below this pressure the films were amorphous as indicated by the X-ray diffraction (XRD). ZnO films were deposited on Al2O3 (0001) at different substrate temperatures varying from 400oC to 600oC and full width half maximum (FWHM) of XRD peak is observed to decrease as substrate temperature increases. The optical band gaps of these films were nearly 3.3 eV. A cylindrical Langmuir probe is used for the investigation of plasma plume arising from the ZnO target. The spatial and temporal variations in electron density and electron temperature are studied. Optical emission spectroscopy is used to identify the different ionic species in the plume. Strong emission lines of neutral Zn, Zn+ and neutral oxygen are observed. No electronically excited O+ cations are identified, which is in agreement with previous studies of ZnO plasma plume.

Optical and electrical properties of co-sputtered amorphous transparent conducting zinc indium tin oxide thin films

Highly conductive and transparent thin films of amorphous zinc indium tin oxide are prepared at room temperature by co-sputtering of zinc 10 oxide and indium tin oxide. Cationic contents in the films are varied by adjusting the power to the sputtering targets. Optical transmission study of 11 films showed an average transmission greater than 85% across the visible region. Maximum conductivity of 6×102 S cm−1 is obtained for Zn/In/ 12 Sn atomic ratio 0.4/0.4/0.2 in the film. Hall mobility strongly depends on carrier concentration and maximum mobility obtained is 18 cm2 V−1 s−1 13 at a carrier concentration of 2.1×1020 cm−3. Optical band gap of films varied from 3.44 eV to 3 eV with the increase of zinc content in the film 14 while the refractive index of the films at 600 nm is about 2.0.

Studies on Mastication Stage Binding of Antioxidants

Paraphenylenediamine and diphenylamine were chemically attached to natural rubber during mastication . The rubber bound antioxidants were characterized by TLC, 'H-NMR, IR and TGA. The efficiency and permenance of these bound antioxidants were compared with a conventional amine type antioxidant in filled natural rubber vulcanizates . The rubber bound antioxidants were found to be less volatile and less extractable as compared to conventional antioxidants. The vulcanizates showed improved ageing resistance as compared to vulcanizates containing conventional antioxidants. This semisolid rubber bound antioxidant can reduce the amount of plasticizer required for compounding.

Studies on the use of nano zinc oxide and modified silica in NR, CR and SBR

Department of Applied Chemistry, Cochin University of Science and Technology

Macrocyclic molecular square complex of zinc(II) self-assembled with a carbohydrazone ligand

A novel N4O coordination mode offers carbohydrazone ligands as a building block for interesting frameworks through self-assembly. Bridging mode of oxygen of bis(2-benzoylpyridine ketone) carbohydrazone (H2L) with metal centers facilitates the formation of the macrocyclic molecular square [Zn(HL)]4(BF4)4 · 10H2O, offers wide range of applications for carbohydrazones.