Vascular Endothelial Growth Factor Expression (VEGF) in Salivary Glands of Young and Old Hyperoxic Rats

Abstract

The aim of this study is to evaluate whether hyperoxia and age can influence the expression of vascular endothelial growth factor (VEGF) in the salivary glands of rats. Our study was carried out on four groups of male Wistar rats (total 24 rats). One group was composed of 6 young rats (3 months old); another group by 6 old rats (24 months old). The rats belonging to the first two groups were exposed to hyperoxia (98–100% O 2 ) for a period of 60–65 hours in a large Plexiglas chamber; the other two groups were control groups. The rats were then anaesthetized with Nembutal (30 mg/kg) intraperitoneally and then killed. The submandibular glands were removed and processed for immunohistochemical analysis of VEGF. The exposure to hyperoxia decreased salivary gland VEGF expression in rats. The tissues analyzed (nervous tissue, vascular endothelium, myoepithelial cells, ductal endothelium, mucinous glands) always expressed VEGF, thus demonstrating that not only vascular endothelial cells, but also the other elements evaluated, have a role in the neoangiogenesis. Only in the serous glands, in both normoxic and hyperoxic young and old rats, was the VEGF expression constantly negative and it did not influence the neoangiogenesis. The vascular growth is a fundamental part of normal salivary gland development, so we speculated that strategies aimed at preservation or promotion of salivary gland VEGF expression may mitigate or attenuate hyperoxia-induced gland microvascular injury. Further studies specifically aimed at investigating these prospects are warranted.