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Fig. 2 | BMC Neuroscience

Fig. 2

From: Effects of melatonin on the nitric oxide system and protein nitration in the hypobaric hypoxic rat hippocampus

Fig. 2

Hippocampal eNOS immunoreactivity in normoxic and hypobaric hypoxic rats pretreated with normal saline or melatonin and sacrificed at 0 h, 1 and 3 days of reoxygenation. In a, light photomicrographs show almost all pyramidal cells in the CA1 region exhibit weak eNOS immunoreactivity in the hippocampus of normoxic rats (A, B, arrows), the latter is drastically increased at 0 h (C), 1 (E) and 3 (G) days after hypoxic exposure. The augment of eNOS immunoreactivity at 0 h, 1 and 3 days post exposure is significantly declined in rats receiving melatonin pretreatment (D, F, H). eNOS(+) neurons of higher magnified in each representative figure are shown in the inserts. Scale bar 50 μm for all figures, insert 100 μm. Quantitative analyses showing the mean optical density of eNOS(+) neurons (b) and the level of total eNOS protein (c) quantified by immunoblots in the hippocampus of rats treated with hypoxia alone (black column) and melatonin pretreated (white column) and sacrificed at 0 h, 1 and 3 days of reoxygenation. The staining intensity and the levels of total protein of eNOS in the hippocamus are drastically enhanced in the rats sacrificed at 0 h, 1 and 3 days after hypoxic insult. In rats treated with hypoxia and pretreated melatonin, the increased intensity of eNOS stain and protein levels are markedly reduced as compared with those of hypoxic along. The staining intensity (b) or protein levels (c) of saline or melatonin treatment under normoxic condition rats are designed as controls (set as 100 %, indicated by dashed line). The levels of β-actin are as a loading control. *P < 0.05 (Student’s t test) when compared with values (expressed as mean ± SEM) of rats merely treated with hypoxia at the same survival time point

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