Early changes in L-arginine-nitric oxide metabolic pathways in response to the whole-body gamma irradiation of rats

Abstract

In contrast to the LPS treatment of rats, the radiation-induced changes in L-arginine-NO metabolic pathways are modest, particularly in the airways and lungs. Noninvasive measurement of exhaled NO within a 24-h period following the exposure of rats to ionizing radiation has no value for biodosimetry.

Radioprotective effect of thymoquinone on salivary gland of rats exposed to total cranial irradiation

“…Under specific conditions, macrophages and certain other cells can produce high concentrations of nitric oxide from its precursor L‐arginine via inducible nitric oxide synthase pathway. Nitric oxide is also formed in higher amounts from L‐arginine by inducible nitric oxide synthase in response to ionizing radiation . Nitric oxide is known, together with other ROS, to induce cytotoxicity and cytostasis.…”

“…The irradiation causes nitric oxide synthase activities that results in increased nitric oxide synthesis, which combines with O 2 – to form peroxynitrite. However, peroxynitrite is much more reactive than nitric oxide or O 2 – , which causes diverse chemical reactions in biological systems, including nitration of tyrosine residues of proteins, triggering of lipid peroxidation, inhibition of the mitochondrial electron transport, oxidation of biological thiol compounds, and damage to DNA . RNS also causes DNA damage, which results in mutation.…”

“…Nitric oxide is also formed in higher amounts from Larginine by inducible nitric oxide synthase in response to ionizing radiation. [47][48][49] Nitric oxide is known, together with other ROS, to induce cytotoxicity and cytostasis. Some studies on nitric oxide-induced and H 2 O 2 -induced oxidative damage have cited similarities between the two chemicals in their enzymatic generation, chemical interaction with macromolecules, and resulting cytotoxicity.…”

Melatonin for Protection Against Ionizing Radiation

“…Extensive studies have established that pretreatment with melatonin at physiological dose 5 mg/kg or pharmacological dose 10 mg/kg bw significantly decreased MDA and NO• levels. The data documented that melatonin reduces tissue damage inflicted by irradiation when given prior to the exposure to ionizing radiation (Babicova et al 2011, Taysi et al 2003, Verma et al 2010. These authors explained that NO• is formed in higher amounts from L-arginine by inducible nitric oxide synthase (iNOS) during early response to ionizing radiation presumably as a part of signal transduction pathways (Babicova et al 2011).…”

“…The data documented that melatonin reduces tissue damage inflicted by irradiation when given prior to the exposure to ionizing radiation (Babicova et al 2011, Taysi et al 2003, Verma et al 2010. These authors explained that NO• is formed in higher amounts from L-arginine by inducible nitric oxide synthase (iNOS) during early response to ionizing radiation presumably as a part of signal transduction pathways (Babicova et al 2011). Its cytotoxicity is primarily due to the production of ONOO-, a toxic oxidant, generated when the NO• couples with O 2 • - (El-Sokkary et al 2002).…”