Substance P is a little known neurotransmitter that is primarily known as the transmitter of pain signals to the brain. But it does much more: it mediates inflammation, it is a neuromodulator, a neurosecretory modulator, modulates movement, modulates mood, and modulates the immune system. It controls stem cell differentiation, metastasis, bone metabolism, most skin disorders, and stomach motility. It is suspected of being the primary cause of multiple types of cancer. It is elevated in all autoimmune disorders. It is also known to modulate cell death.

The main influence that substance P has on the body is that it opens up cell membranes, thus lowering cell membrane potential. This causes neuron cells to fire too easily. This leads to hypersensitivity, loss of homeostasis, and can cause neurons to become exhausted and die off. When the cell membrane becomes more permeable, there is a prolonged calcium influx into the cell, which interferes with internal cell communication.

Substance P has been implicated as a possible cause of Parkinson’s. The highest levels of substance P in the brain are found within the substantia nigra, the nucleus where dopamine cells die off in Parkinson’s disease. Research by Emma Thorton, PhD (Australia, 2008) has shown that experimental Parkinson’s disease could be reversed by treating animals with a substance P antagonist (

Serum levels of substance P levels are known to increase by over tenfold with bite dysfunction. It is likely that it is through modulation of substance P levels that TMJ therapy has its effect on Parkinson’s disease. In addition, disturbances within the trigeminal nerve (jaw nerve) are known to cause glial activation (cells within the brain), a known condition accompanying Parkinson’s disease and dementia. The trigeminal nerve through glial control is a major modulator of regional cerebral blood flow, a system that is also dysfunctional in Parkinson’s disease.

There are very few approved substance P antagonist medications. Aprepitant (Emend/Merck), approved for nausea and vomiting being the primary one (see Wikipedia: NK1 antagonist).

For more information on TMJ Therapy and Dr. Jennings, go to the WELLNESS VILLAGE on the PRO website.

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Updated: August 16, 2017