Cystatins interfere in the functioning of antidepressant (MAOI) therefore MAOI may not be able to act on monoamine Oxidase (MAO) and the destruction of Serotonin continues which leads to depression. The effect of neurotransmitter has been studied to explore the serotonin induced cystatin dysfunction.
When 1μM of cystatin was treated with increasing concentrations of serotonin, the cystatin showed increase in fluorescence intensity and decrease in absorbance, functional study shows a continues loss in antiproteolytic activity with increasing concentration of serotonin results indicated unfolding of cystatin which may not be able to regulate the activity of cathepsins leading to protease- antiprotease imbalance, which may be a cause of several diseases.
Neurotransmitters are endogenous chemicals which relay, amplify, and modulate signals between a neuron and another cell. Release of neurotransmitters usually follows arrival of an action potential at the synapse, Serotonin is a monoamine neurotransmitter. It is synthesized in serotonergic neurons in the central nervous system (CNS) where it has various functions, including control of appetite, mood and anger. Cystatins are the inhibitors of cysteine proteinases most of which form equimolar complexes with their target enzymes.
They are the members of cystatin super family. They are present in a variety of tissues, body fluids of human beings and animals to regulate the activities of cysteine proteinases.