It has been shown that the leukotriene receptors CysLTR1 and CysLTR2 in different brain cells, namely microglia (known as the brain’s immune system), astrocytes, and several types of neurons, are upregulated in response to brain injury such as brain ischemia, Alzheimer’s disease, and Parkinson’s disease [62,63,64,65,82,83,84,85,86,87,88]. This evidence concerns the gene CYSLTR2 and Parkinson disease.