Enhancement of Glial Cell Line-Derived Neurotrophic Factor Expression in Rat Adrenal Glands by Toluene Exposure

Toluene, a widely used industrial organic solvent, has been shown to influence the function of catecholaminergic cells including sympathoadrenergic neurons and adrenal medullary cells. While glial cell line-derived neurotrophic factor (GDNF), a member of the transforming growth factor-β superfamily, has recently been shown to be expressed in rat adrenal glands, and suggested as playing a potential autocrine or paracrine role in development and differentiation of the adrenal medullary cell. Based on these findings, it seemed of interest to examine the effect of toluene exposure on GDNF expression in the adrenal medulla. Toluene inhalation (1500 ppm for 4 h on 4-10 days) increased GDNF protein content in rat adrenal glands without any significant change in GDNF mRNA level. Furthermore, toluene exposure failed to cause any notable change in the expression of mRNA encoding phenylethanolamine N-methyltransferase (PNMT), a stress-inducible enzyme in the adrenal medulla. These results suggest that the elevation of GDNF protein expression caused by toluene exposure is likely due to the enhancement of protein synthesis and/or processing rather than the stimulation of GDNF gene transcription in rat adrenal glands, and may not be directly associated with the stress response of adrenal glands during toluene inhalation.

Key words

Toluene Exposure - GDNF Expression - PNMT mRNA - Stress Response - Rat Adrenal Gland