Neurophysiological study on possible protective and therapeutic effects of Sidr (Zizyphus spina-christi L.) leaf extract in male albino rats treated with pentylenetetrazol

In this study, anti-convulsant effect of Sidr leaf extract was examined by using pentylenetetrazol (PTZ) model on male albino rat by evaluating the changes in norepinephrine (NE), dopamine (DA) and serotonin (5-HT) contents in different brain regions (cerebellum, brainstem, striatum, cerebral cortex, hypothalamus and hippocampus). The administration of subconvulsive dose of PTZ (40 mg/kg i.p.) every other day for 9 days caused a significant decrease in monoamine content in different brain areas, this is may be due to the increase in nitric oxide levels, although antagonized the GABAA receptors which led to neurotransmitter release so the content is decreased. Administration of PTZ after treatment with Sidr (50 mg/kg i.p.) leaf extract for 3 weeks as a protective group and administration of Sidr leaf extract for 3 weeks after treatment of PTZ as a therapeutic group caused significant increase in NE, DA, and 5-HT contents in all tested brain regions at most of the time intervals studied. This may be due to the presence of peptide and cyclopeptide alkaloids in the extract which inhibit neurotransmitter activity which led to the inhibition of neurotransmitter release. From these results, we can say that the Sidr leaf extract has neuroprotective and therapeutic roles against pentylenetetrazol convulsant effect.     

Biochemical characterization of various populations of isolated bovine adrenal chromaffin cells

Various populations of bovine adrenal chromaffin cells were isolated first by successive digestions with collagenase (original cell preparation) followed by sedimentation through a stepwise bovine serum albumin gradient (cell layers I, II and III). At the fine structural level, the ratios between the number of adrenaline-cells and noradrenaline-cells were 1.9 in the original cell preparation and 0.9, 2.0 and 4.6 in cell layers I, II and III, respectively. The catecholamine content of each cell population was also measured by spectrofluorometry. The original cell preparation contained 20.1 and 12.2 nmol per 10⁶ cells of adrenaline and noradrenaline, respectively. Each cell layer had similar total amount of catecholamines (from 38.3 to 40 nmol per 10⁶ cells) but their adrenaline/noradrenaline content ratios varied from 0.6 in cell layer 1 to 1.3 and 3.3 in cell layers II and III, respectively. Incubation of the cells in the presence of acetylcholine (50 μM) induced a release of catecholamines which was proportional to the cell content of each amine. However, the percentage of total cell content released was much higher in cell layer I (20%) than in cell layers II (8%) and III (5%). Finally, each cell population was also analyzed for its ability to respond to a muscarinic stimulation of cyclic GMP level and to bind [³H]etorphine, a highly potent opiate agonist. Acetylcholine induced 3.15-, 2.15- and 4.21-fold increases in the levels of cyclic GMP in the original cell preparation, cell layers II and III, respectively, but not in cell layer I. Conversely, the high affinity opiate binding site for [³H]etorphine was almost exclusively confined to cell layer III (B_max of 28.4 fmol per 10⁶ cells as compared with 2.8–7.5 fmol in the other cell preparations). These results indicate that bovine adrenal chromaffin cells can be separated according to their content in adrenaline and noradrenaline and their response to nicotinic, muscarinic and opiate stimuli.     

Control of lateral root initiation by DA3 in Arabidopsis

1. Download : Download high-res image (133KB)
2. Download : Download full-size image