Effect of subacute toluene administration on the enkephalinergic neuromodulatory system in rats and protective action of ganglioside treatments

Toluene inhalation induced 8-hydroxy-2'-deoxyguanosine formation as the peroxidative degeneration in rat organs

The effect of toluene inhalation on oxidative damage in rat organs was examined. Male Wistar rats was inhaled toluene (1500 ppm for 4 h a day) for 7 days. Quantitatively and immunohistochemically, oxidative DNA damage, lipid peroxide (LPO) and superoxide dismutase (SOD) were examined. As a marker of the oxidative DNA damage, 8-hydroxy-2'-deoxyguanosine (8-OH-dG) immunoreactivity increased in the lung, liver and kidney. The amount of 8-OH-dG also increased in liver and kidney significantly. In the testis, the amount of 8-H-dG did not increase, however 8-OH-dG immunoreactivity enhanced in the spermatogonia. SOD immunoreactivity increased in the lung, liver and kidney. However, 4-hydroxy-nonenal immunoreactivity and the amount of LPO did not change in each organ. Thus, oxidative damage by toluene is mainly DNA damage, especially, the oxidative DNA damage observed in the lung, liver and kidney for the increase of the immunoreactivity and amount of 8-OH-dG.

Effects of acute benzene exposure on brain enkephalin immunostaining and degradation

Benzene is a widely used industrial neurotoxin. Its action in the brain is not completely clear. Acute exposure to benzene in vivo reduces aminopeptidase activity in the hypothalamus and in the brain stem, and in vitro treatment with this toxicant generates a dose-related inhibition of this enzyme, notably in the brain stem. Enkephalin immunostaining shows a significant increase in substantia nigra, central gray (dorsal, lateral and pontine), and tegmental nuclei in acute in vivo benzene-treated rats with respect to controls. In summary, this work shows an effect of benzene on the enkephalinergic system, which could be related to the naloxone-reversible analgesia induced by the aromatic hydrocarbon.

Endogenous opiates: 1994

This article is the 17th installment of our annual review of research concerning the opiate system. It includes papers published during 1994 involving the behavioral, nonanalgesic, effects of the endogenous opiate peptides. The specific topics covered this year include stress; tolerance and dependence; eating; drinking; gastrointestinal, renal, and hepatic function; mental illness and mood; learning, memory, and reward; cardiovascular responses; respiration and thermoregulation; seizures and other neurological disorders; electrical-related activity; general activity and locomotion; sex, pregnancy, and development; immunological responses; and other behaviors.