Deficiencies as PD cause/Norepinephrine
Norepinephrine is also known as noradrenline and more commonly as the 'fright and flight' compound.
Norepinephrine is synthesized from dopamine by dopamine β-hydroxylase. It is released from the adrenal medulla into the blood as a hormone, and is also a neurotransmitter in the central nervous system and sympathetic nervous system where it is released from noradrenergic neurons in the locus coeruleus. The actions of norepinephrine are carried out via the binding to adrenergic receptors.
A sudden shock produces an autonomic reaction in the sympathetic nervous system, generating a pulse of norepinephrine, which speeds up the action of the heart and charges the limbs with fresh, oxygenated blood, ready to run or take other reactive action.
The National Institute of Neurological Disorders and Stroke – NINDS  gives an account of the research of Dr. David Goldstein Chief of the Clinical Neurocardiology Section at NINDS. Using positron emission tomography (PET) scans, researchers at the National Institute of Neurological Disorders and Stroke (NINDS) found that nearly all of the 29 Parkinson's disease patients they studied had decreased numbers of norepinephrine-producing nerve endings in the heart. This can lead to a sudden drop in blood pressure termed ‘ orthostatic hypotension’.
- Goldstin, David (1999) “Parkinson’s Diseasei ore tha a brain disorder.” http://www.ninds.nih.gov/news_and_events/news_articles/pressrelease_parkinson_090400.htm