Effect of hydrogen peroxide on secretory response, calcium mobilisation and caspase-3 activity in the isolated rat parotid gland

Abstract

The parotid glands are highly active secretory systems subjected to continuous stress, which in turn, can lead to several pathophysiological conditions. Damage of the parotid glands are caused by radical oxygen species (ROS) as by-products of oxygen metabolism. This study investigated the effect of hydrogen peroxide (H(2)O(2)) on Carbachol (CCh)-evoked secretory responses and caspase-3 activity in the isolated rat parotid gland to understand the role of oxidative stress on the function of the gland. Amylase secretion, cytosolic calcium concentration ([Ca(2+)](i)) and caspase-3 activity in parotid gland tissue were measured using fluorimetric methods. H(2)O(2) had little or no effect on amylase secretion compared to basal level. Combining H(2)O(2) with CCh resulted in an attenuation of the CCh-evoked amylase secretion compared to the effect of CCh alone. CCh can evoke a large increase in [Ca(2+)](i) comprising an initial peak followed by a plateau. In a Ca(2+)-free medium containing 1 mM EGTA, CCh evoked only the initial peak of [Ca(2+)](i). H(2)O(2) alone evoked a gradual and dose-dependent increase in [Ca(2+)](i). Combining H(2)O(2) with CCh resulted in a decrease in [Ca(2+)](i) compared to the effect of CCh alone. In a Ca(2+)-free medium, H(2)O(2) still evoked a small increase in [Ca(2+)](i), but this response was less compared to the results obtained with H(2)O(2) in normal [Ca(2+)](0). Combining H(2)O(2) with CCh resulted in only a small transient increase in [Ca(2+)](i). Following CCh stimulation, H(2)O(2) application resulted in a large increase in [Ca(2+)](i) in normal [Ca(2+)](0). This effect of H(2)O(2) was partially abolished in a nominally free Calcium medium containing EGTA. H(2)O(2) can stimulate caspase-3 activity in parotid gland tissue. Similar response was obtained with betulinic acid and thapsigargin (TPS) on caspase-3 activity compared to basal. The results have demonstrated that like CCh, H(2)O(2) can also mobilise Ca(2+) from intracellular stores and facilitate its influx into the cell from extracellular medium. This effect of H(2)O(2) may be due to its activity to induce apoptosis in the parotid gland, since H(2)O(2) can stimulate the activity of caspase-3, a marker of cellular apoptosis.

Supplementation of kaempferol toin vitromaturation medium regulates oxidative stress and enhances subsequent embryonic developmentin vitro

“…ROS are a double-edged sword: low levels of ROS are key signalling molecules in many pathophysiological processes and excessive ROS play a key role in destroying cellular components and triggering cell death (Li et al, 2019). The continuous increase in calcium ions may lead to oxidative stress and cell death (Mata et al, 2008). Intracellular calcium overload leads to the accumulation of mitochondrial calcium ions, changes in mitochondrial pH, increases in ROS production, decreases or completely losses in mitochondrial ΔΨm and changes in mitochondrial permeability (Choi, 2011).…”

Hydrogen peroxide attenuates the dipsogenic, renal and pressor responses induced by cholinergic activation of the medial septal area

“…Scale bar = 100 and 200 lm, respectively, higher magnification and inset. phospholipase C in human neuroblastoma cells or the secretory response in the isolated rat parotid gland was seen with the pre-treatment with H 2 O 2 in in vitro preparations (Li et al, 1996;Mata et al, 2008). The present results showing that the treatment with H 2 O 2 into the MSA reduced the responses to cholinergic stimulation in the MSA are comparable to those from previous studies, and further demonstrate a central action of H 2 O 2 reducing the responses to central cholinergic activation, particularly in the MSA.…”

“…In addition to inhibiting ANG II pressor responses, H 2 O 2 also affects cholinergic mechanisms, decreasing carbachol-induced phosphoinositide hydrolysis by phospholipase C in human neuroblastoma cells (Li et al, 1996) and amylase secretion (Mata et al, 2008). Therefore, H 2 O 2 may negatively modulate the actions of carbachol by affecting muscarinic receptor function or intracellular pathways.…”

Thiol-oxidation reduces the release of amylase induced by β-adrenergic receptor activation in rat parotid acinar cells

“…However, it is possible that S-glutathionylation is involved in regulating β-adrenergic receptor function under mild oxidative stress in rat parotid acinar cells, although further studies are needed to examine this. Oxidative stress induced by hydrogen peroxide has recently been reported to reduce the release of amylase provoked by the muscarinic agonist carbachol in parotid acinar cells (17). The muscarinic agonist-induced release of amylase occurs via increases in intracellular Ca 2+ levels, and oxidative stress has been suggested to attenuate the Ca 2+ mobilization.…”