Regional alterations of brain catecholamines by styrene exposure in rabbits

Abstract

The regional distribution of dopamine, norepinephrine and homovanillic acid was assessed in adult male rabbits exposed to styrene vapours. The turnover of dopamine and norepinephrine was also measured in several brain regions by the decay in endogenous catecholamines after inhibition of tyrosine hydroxylase by alpha-methyl-p-tyrosine. Styrene exposure produced a marked and dose-dependent decrease in striatal and tuberoinfundibular dopamine, associated with a consistent increase in homovanillic acid content in the same regions. Norepinephrine levels were unaffected by styrene exposure. The observed increase in catabolism of dopamine cannot be explained by the turnover time, which was not significantly different in the exposed as compared to the control rabbits. Competition of a styrene metabolite with dopamine for the vesicular storage capacity or a selective destruction of dopaminergic terminals are suggested as the possible mechanisms for styrene neurotoxicity.

Effects of 5-day styrene inhalation on serum prolactin and dopamine levels and on hypothalamic and striatal catecholamine concentrations in male rats

“…Data represent means +SEM, n=10 rats per group. There were no significant differences observed between the treatment and control groups styrene exposure, a depletion of DA in the striatum and the tuberoinfundibular area of the hypothalamus has been observed, respectively, in rabbits (Mutti et al 1984) and rats (Chakrabarti 2000). However, in the present study we did not observe any of such effects.…”

“…Upon styrene exposure, a depletion of DA in the striatum and the tuberoinfundibular area of the hypothalamus has been observed, respectively, in rabbits (Mutti et al 1984) and rats (Chakrabarti 2000). However, in these studies PRL levels were not assessed.…”

“…Based on the dopaminergic regulation of PRL release and slightly elevated PRL levels measured in occupationally styreneexposed workers, Mutti's group conducted experiments with rabbits (Mutti et al 1984(Mutti et al , 1985, and reported that a 3-or 7-day exposure of the animals to styrene reduced hypothalamic DA concentrations. These observations were also made in the corpus striatum, an extrahypothalamic, DA containing, brain region in which locomotor function is controlled.…”

Changes in Middle Latency Auditory-Evoked Potentials of the Rat Exposed to Styrene.

“…[8][9][10] In addition, an investigation by Mutti et al showed that styrene exposure to rabbits resulted in a marked dose-dependent decrease in the striatal dopamine (DA) concentration. 11,12) Moreover, a similar effect was also described when phenylglyoxylic acid (PGA) and phenylglycine (PG), important metabolites of styrene, were administered. 13) These results suggested that the DA metabolism may be a target for the neurotoxic effect of styrene and its metabolites.…”

NTP‐CERHR Expert Panel Report on the reproductive and developmental toxicity of styrene

“…In separate experimental animal studies, the effects of styrene exposure on hypothalamic dopamine concentrations were evaluated. Decreased tuberoinfundibular dopamine levels were observed in rabbits exposed by inhalation to 1500 ppm for 12 hr/day for 3 or 7 days (Mutti et al, 1984a). Decreased hypothalamic dopamine levels were also observed in rats treated orally with styrene 500 mg/kg bw/day for 13 weeks (Chakrabarti, 2000).…”