The Silver Nanoparticles Induce C-Fos Expression in the Central Nucleus of Amygdala That Relief the Aversive Effect of Naloxone in the Morphine Relied Animal

Abstractbackground: silver nanoparticles (agnps) that are used daily in care service can enter the body and create free radicals. despite the toxicity at high concentrations, these particles are nontoxic and useful at low concentrations. thus, we investigated the effectiveness of nontoxic agnps to interfere with the aversive effect of naloxone (nlx) and low expression of cfos during testing of morphineinduced conditioned place preference (cpp) in rats. methods: the wistar rats (weighing 300350 g) were cannulated bilaterally by stereotaxic apparatus for the cea (ap= –2.12 mm; l= ±4.1 mm; v= 7.8 mm). cpp was conducted via a threephase unbiased procedure. morphine (0.57.5 mg/kg) was injected subcutaneously (sc) during the conditioning phase. nlx (0.4 µg/rat) was given, intracea, 10 min before the test. agnps (0.01 µg/rat) was administered prior to the antagonist. the control group received saline (1 µl/rat, intracea). cfos expression was quantified immunohistochemically in rats subsequent the injections: results: the cea and hippocampal cornu ammonis 1 (ca1) of rats that treated by nlx showed low cfos protein levels during testing, whereas levels of protein were high in the brains of morphine conditioned rats. interestingly, both areas (cea and ca1) showed similar increases in protein levels when the injection of nlx was combined with the agnps. however, these regions were not significantly different in the single agnps receiving and control groups. conclusions: this indicates that the two regions interact with each other when nlx is injected and that in presence of agnps the protein levels are elevated in the regions.