The research progress for the role of reactive oxygen species in the occurrence of noise-induced hearing loss / 医学研究生学报

Noise-induced hearing loss (NIHL) is defined by a strong noise exposure led up the hair cells to damage which caused sensorineural hearing loss.The occurrence of NIHL is mainly related to oxidative damage, such as reactive oxygen species.Oxidative damage is mainly related to the ROS produced by noise exposure which can cause cochlear ischemia, hypoxia, and mitochondrial damage, resulting in hair cell death, further led to hearing loss.Prevention or treatment measures of NIHL is to reduce the formation of ROS and the removal of ROS.Antioxidants have been used in clinical treatment.This article reviews the effects of reactive oxygen species in NIHL to further explore the pathogenesis and prevention or treatment measures of NIHL.

Antinociceptive effects of vitamin E in formalin-induced nociceptive response in rats

BACKGROUND: Reactive oxygen species (ROS) are critically involved in generating pain in various painful conditions, including neuropathic and inflammatory pain. This experiment was conducted in order to assess the antinociceptive effects of vitamin E in the modulation of pain in rats subjected to the formalin test. METHODS: Five percent formalin was injected into the hind paw after intraperitoneal injection of either vitamin E 1 g/kg dissolved in olive oil or olive oil alone. The Number of flinches were measured in a 5 minute interval for 1 hour. RESULTS: Formalin injected into the left hind paw induced a biphasic nociceptive behavior. Intraperitoneal injection of vitamin E diminished the nociceptive behavior during phase 1 and 2. CONCLUSIONS: Systemic administration of vitamin E produces analgesia in a rat model of formalin-induced hyperalgesia. Furthermore, vitamin E affects pain of peripheral origin.

Inducibility of superoxide dismutases and metallothionein in the liver and kidney of mice by paraquat with age / 대한내과학회지

BACKGROUND: A number of theories have been proposed to explain the nature of aging process. Unfortunately, there is so far no theory that can completely explain all aging processes. In the present study, to investigate roles of inducibility of defense mechanisms by oxidative stress, cellular mRNA level of superoxide dismutases (SODs) and metallothionein (MT) as well as their inducibility by paraquat, an intracellular superoxide generator, was examined in the liver and kidney of the mice of aging process. METHODS: The steady-state levels of SODs and MT mRNA and their induction by paraquat were determined by the RT-PCR assay in male mice of 4 ages, 1, 4, 8, and 12 months. RESULTS: In the liver, the steady-state levels of Mn-SOD, Cu/Zn-SOD and MT mRNA increased until 8 months with age and decreased significantly at 12 months. Cu/Zn-SOD and MT mRNA were induced well by paraquat at all ages but Mn-SOD mRNA not at 12 months. In the kidney, their mRNA levels of Mn-SOD, Cu/Zn-SOD and MT increased with age. Mn-SOD mRNA was induced by paraquat only at 1 month but Cu/Zn-SOD mRNA not at all ages. On the other hand, MT mRNA was significantly induced by paraquat at all ages. CONCLUSION: These results suggest that SODs and MT are differentially expressed and induced according to the age and organs. In addition, it is thought that the lack of induction of Mn-SOD by oxidative stress in both the liver and kidney may be one of causative factors in the aging process while Cu/Zn-SOD and MT in the liver and MT in the kidney may play protective roles in the aging process. It is therefore implicated that the tissue antioxidant/prooxidant balance could be one of determinants of mean life span.

Role of Inducibility of Superoxide Dismutases and Metallothionein of Mouse Lungs by Paraquat in Aging / 결핵

BACKGROUND: The aging process may be induced, at least in part, by reactive oxygen species(ROS). It has been though that the lung could be a good source of ROS because it has a high oxygen tension. In the present study, we invetigated the inducibility of the first and last lines against oxidative stress, superoxide dismutases (Cu/Zn-SOD and Mn-SOD) as a scavenger of O2- and metallothionein(MT) as a scavenger of OH·, respectively, in mouse lungs with age. METHODS: Oxidative stress was induced by paraquat, an intracellular superoxide generator, at 1, 4, 8, and 12 months of age and then SODs and MT mRNAs were determined by RT-PCR method. RESULTS: The steady-state level of Mn-SOD mRNA increased from 1 to 8 months but decreased thereafter. However, Mn-SOD mRNA was not induced by paraquat after 1 month. On the other hand, there was no change in the steady-state level of Cu/Zn/-SOD mRNA, which decrease abruptly at 12 months of age. Additionally, Cu/Zn/-SOD mRNA was not induced by paraquat at any age. There was no change in the steady-state level of MT mRNA with age whereas its inducibility by paraquat was intact at all ages. CONCLUSION: These results indicate that lack of induction of SODs with age may be one of the causative factors in the aging process while induction of MT may play an important role in the defense against oxidative stress. It is therefore implicated that the tissue antioxidant/proxidant balance could be one determinants of meal life span.