Ultrastructural
Demonstration of NADPH-Diaphorase, a Marker for Nitric Oxide
Synthase in Hypothalamo-Neurohypophysial System, Hippocampus
and Cerebral Cortex of the Rat After Ischemia by Barbara Gajkowska and Michal Walski
Abstract:
An
electron-microscopic histochemical study was performed in order
to determine the expression pattern of nicotinamide adenine
dinucleotide phosphate diaphorase (NADPH-d) in hypothalamo-neurohypophysial
system (HNS), hippocampus and cerebral cortex of rat's brain
after ischemia. In basal conditions NADPH-d to be weakly expressed
in small population of neuronal cells in HNS and hippocampus
and in population of endothelial cells of capillary vessels
in all examined regions of the brain. Short time after ischemia,
upregulation NADPH-d expression was observed. NADPH-d was rapidly
upregulated at 10 min and progressively increased 1-6 h after
ischemia. A strong enzyme histochemical staining for NADPH-d
was located in some neurosecretory neurons, astrocytes and cellular
elements of capillary vessels of hypothalamus and in fibers,
terminals, pituicytes and capillary vessels of neurohypophysis.
The results suggest that increase in activity of NOS occurs
during cerebral ischemia is involved in modulation of HNS. Also,
the strong distribution of NADPH-d activity was found in capillary
vessels, perivascular astrocytes and in some neurons associated
with capillaries of hippocampus. The participation of NOS neurons
and astrocytes in the changes in cerebral blood flow and microvascular
function in ischemic tissue remain to be determined.
