CATECHOLAMINES By Hawra Alsofi

DEFINITION catecholamine is a monoamine neurotransmitter, an organic compound that has a catechol and a side-chain amine.\ 3 types : I.Adrenalin (epinephrine). II.Noradrenaline (norepinephrine ). III.Dopamine.

Location Produced mainly by : i.Chromaffin cells of adrenal medulla. ii.Postganglionic fibers of sympathetic nervous system. Dopamine mainly postganglionic fibers of brainstem (are substantia nigra, ventral tegmental area )

Degradation The half-life of catecholamines in the blood (few minutes ). Catabolism by 2 enzymes: 1.COMT (Catechol -O -Methyltransferase ) 2.MAO (Mono-Amin-Oxidase ) these 2 enzymes need cofactors :  COMT Mg  Cause COMT found in synaptic cleft  MAO FAD  Cause MAO found in mitochondrial membrane

Function Neuromodulators in CNS 2 catecholamines as Dopamine & norepinephrine Hormones in the blood

Effects of catecholamines cause general physiological changes that prepare the body for physical activity (fight or flight response ). heart rate blood pressure Typical effects blood glucose levels general reaction of sympathetic NS

Catecholamine in blood psychological stress (emotional reaction ). By stress environmental stress : elevated sound level intense light low blood pressure

Extreme catecholamine in blood catecholamine toxicity as result of 1.CNS trauma case damage of nuclei in brainstem. 2.Neuroendocrine tumors (in the adrenal medulla ) ex. Pheochromocytoma