Hassan Azhdari-Zarmehri, Mohammad Mohammad-Zadeh, Masoud Feridoni, Masoud Nazeri,
Volume 5, Issue 1 (Winter 2014 -- 2014)
Abstract
Introduction: Formalin injection induces nociceptive bahaviour in phase I and II, with a quiescent phase between them. While active inhibitory mechanisms are proposed to be responsible for initiation of interphase, the exact mechanisms which lead to termination of nociceptive response in phase II are not clear yet. Phase II is a consequence of peripheral and central sensitization processes, which can lead to termination of the noxious stimuli responses 45-60 minutes after formalin injection via possible recruitment of active inhibitory mechanisms which we have investigated in this study.
Methods: To test our hypothesis, in the first set of experiments, we evaluated nociceptive response after two consecutive injection of formalin (50&muL, 2%), with intervals of 5 or 60 minutes. In the next set, formalin tests were carried out in companion with injection of Naloxone Hydrochloride, a non-selective antagonist of opioid receptors, pre-formalin injection and 30 and 45 minutes post formalin injection.
Results: While normal nociceptive behaviour was observed in the group receiving one injection of formalin, a diminished response was observed in phases I and II of those receiving consequent injection of formalin, 60 minute after first injection. While second injection of formalin, 5 minute after first injection, had no effect. Administration of naloxone (1mg/kg) decreased nociception in phase 2A but had no effect on delayed termination of formalin test.
Discussion: The results of this study suggest the existence of an active inhibitory mechanism, other than the endogenous opioids, that is responsible for termination of nociceptive behaviour at the end of formalin test.
Mohammad Mohammad-Zadeh, Hassan Azhdari-Zarmehri, Faeze Mosavi, Mohammad Shabani,
Volume 5, Issue 4 (Autumn 2014 2014)
Abstract
Introduction: The formalin test is the most accepted chemical test for evaluation of nociception. It requires the injection of an adequate amount of formalin into the surface of the hindpaw. Formalin test consists of phase 1 (0-7 min) and phase 2 (15-60) in which the animal shows painful behaviors. These phases are separated with a quiet phase named interphase, in which the nociceptive responses are decreased or completely disappeared.
Methods: The goal of the current study was to evaluate the effects of swim stress at different heights of water on different phases of the formalin test in male rats.
Results: Swim stress decreased nociceptive behaviors in first phase and prolonged interphase or delayed the start of second phase in a water height dependent manner. Swim stress in 25 and 50cm completely abolished the nociceptive behaviours in phase 1.
Discussion: The present results showed different pain modulation during different phases of the formalin test and elucidated the impact of swim stress on duration of interphase. Interphase considered as an inactive period, but a recent research has shown that active inhibitory mechanisms are involved in the modulation of pain during this period. Therefore, swim stress may consider as a useful tool for study of the basic inhibitory mechanisms underlying attenuation of nociceptive behaviors between phase 1 and 2 of the formalin test.
Ghasem Majdi Yazdi, Gholamhasan Vaezi, Vida Hojati, Mohammad Mohammad-Zadeh,
Volume 12, Issue 3 (May & June 2021)
Abstract
Introduction: Research has shown that gold nanoparticles (AuNPs) can damage the physiological processes of brain tissue. Given the antioxidant properties of Gingerol (GING), this study aimed to determine the protective effect of 6-gingerol on hippocampal levels of Brain-Derived Neurotrophic Factor (BDNF), Nerve Growth Factor (NGF), DNA oxidative damage, and the amount of Bax and Bcl2 apoptosis indices of rats exposed to AuNPs.
Methods: A total of 42 male Wistar rats were divided into four groups: control (30 days 0.5 mL saline), AuNPs (one time injection of 0.5 mL AuNPs, 200 ppm and 60 Nm + 30 days 0.5 mL saline), AuNPs+GING 50 (one time injection of 0.5 mL AuNPs, 200 ppm and 60 Nm + 30 days 0.5 mL density of gingerol 50 mg/kg), and AuNPs+GING100 (one time injection of 0.5 mL AuNPs, 200 ppm and 60 Nm + 30 days 0.5 mL density of gingerol 100 mg/kg). At the end of the treatment period, the hippocampal levels of NGF, BDNF, 8-hydroxy-desoxyguanosine (8-HOdG), and apoptotic indices of Bax and Bcl-2 were assessed with the ELISA method.
Results: Compared with the AuNPs group, hippocampal levels of BDNF, NGF, and Bcl-2 in rats in the AuNPs+GING 50 and AuNPs+GING 100 groups significantly increased dose-dependently. However, the hippocampal levels of Bax and 8-HOdG significantly decreased dose-dependently (P<0.05).
Conclusion: According to obtained results, gingerol may improve hippocampal BDNF and NGF levels in rats exposed to AuNPs, probably by reducing apoptosis and oxidative DNA damage.
