Chemica Pollutants and Itching: What Does Nerve Growth Factor Have to Do With It?

Background: Nerve growth factor (NGF) is a neurotropin that is important for the growth and survival of neurons and is believed to be important to preventing neural degeneration (in some cases and not others) and is present in larger amounts in inflamed tissue. (Wipedia, Pehar) On the other hand, it upregulates nociceptors and may play a role in neuropathic pain.  Altered nociception and ASICs signaling have both been implicated as a factors in multiple chemical sensitivity (Pall) and other environmentally-induced health conditions. In certain studies it has also been shown that the level of NGF is correlated to the severity of itching in atopy. Toluene is an air pollutant and is found in low or high amounts in homes and commercial buildings.

Two studies may shed more light on understanding the "itch" that is commonly associated with some cases of environmental illness. The first study provides an explanation of how air pollutants, in this case, toluene effects physiological systems. According to the first study findings, low-level toluene induced a significant increase in CCL2 (MCP-1) and CCL3 and cells positive for nerve growth factor while showing insignificant markers for oxidative stress and HO-1 in controls and immunized mice. Immunized mice were treated to model allergic animals. The findings of this study show that volatile organic compounds (ie toluene) enhance nerve growth factor production and airway inflammation is more severe in allergic animals.(Fujiama) Interestingly, another study, shows that dioxin, an activator of the AhR, caused itching when the experiment animal was exposed to another generally inocuous stimulus. In the study, it was demonstrated that the itching of this type was alleviated with pharmaceuticals that reduce skin levels of NGF. (Ono)

HEIRS Library Tags: nerve growth factor

Notes:

• There is an important relationship of Nrf2 and HO-1 in the consequences of activity by nerve growth factor which may include reduction of ROS and protection against endogenous environmental insults including dopamine toxicity. (Salinas)

Fujimaki, H., Tin-Tin-Win-Shwe, Yamamoto, S., Nakajima, D., and Goto, S. (2009). The expression of nerve growth factor in mice lung following low-level toluene exposure. Toxicology letters, 191(2-3):240-245. http://www.citeulike.org/user/HEIRS/article/5808711#
Pall, M. L. and Anderson, J. H. (2004). The vanilloid receptor as a putative target of diverse chemicals in multiple chemical sensitivity. Archives of environmental health, 59(7):363-375. http://www.citeulike.org/user/HEIRS/article/5911051
Diogenes, A., Akopian, A. N., and Hargreaves, K. M. (2007). Ngf up-regulates trpa1: Implications for orofacial pain. J Dent Res, 86(6):550-555. http://www.citeulike.org/user/HEIRS/article/3682087
Yamaguchi, J., Aihara, M., Kobayashi, Y., Kambara, T., and Ikezawa, Z. (2009). Quantitative analysis of nerve growth factor (ngf) in the atopic dermatitis and psoriasis horny layer and effect of treatment on ngf in atopic dermatitis. Journal of dermatological science, 53(1):48-54. http://www.citeulike.org/user/HEIRS/article/6453209
Ono, R., Kagawa, Y., Takahashi, Y., Akagi, M., and Kamei, C. (2009). Effect of 2,3,7,8- tetrachlorodibenzo-p-dioxin on scratching behavior in mice. International immunopharmacology. http://www.citeulike.org/user/HEIRS/article/6409196
Pehar, M., Vargas, M. R., Robinson, K. M., Cassina, P., Diaz-Amarilla, P. J., Hagen, T. M., Radi, R., Barbeito, L., and Beckman, J. S. (2007). Mitochondrial superoxide production and nuclear factor erythroid 2-related factor 2 activation in p75 neurotrophin receptor-induced motor neuron apoptosis. J. Neurosci., 27(29):7777-7785. http://www.citeulike.org/user/HEIRS/article/3733200?updated=1262024743
Salinas, M., Diaz, R., Abraham, N. G., Ruiz de Galarreta, C. M., and Cuadrado, A. (2003). Nerve growth factor protects against 6-hydroxydopamine-induced oxidative stress by increasing expression of heme oxygenase-1 in a phosphatidylinositol 3-kinase-dependent manner. Journal of Biological Chemistry, 278(16):13898-13904. http://www.citeulike.org/user/HEIRS/article/6456500