Central Nervous System:::
5-HT is normally found in the brain (1%) and its deficiency is presumed to produce depression hence psychomotor drugs i.e antidepressants show an increase in efficiency if tryptophan the basic amino acid from which 5-HT is synthesized is given the complete role of serotonin in psychopharmacology is complex it is now established well to be a very important neurotransmitter in brain serotonergic neurons are involved in sleep temperature regulation B.P regulation and vomiting etc
The argentaffin cells reproduce with great rapidity in some pathological conditions and such an increase results in a tumor called carcinoid tumour 5-HT is found in large quantity in such tumors it was wrongly thought to be responsible for attacks of flushing it is the liberation of kinin from the tumor which gives analogous flushing as of substance P that is responsible for attacks of flushing Detection of large quantity of 5-hydroxyindolacetic acid in urine is a diagnostic test for the presence of such tumors
PURINES::
Purines especially adenosine and purine nucleotides especially ADP and ATP produce a wide range of pharmacological effects that are not directly related to their role in energy metabolism it was shown in 1929 that adenosine injected into anaesthetised animals causes cardiac slowing a fall in blood pressure vasodilatation and inhibition of intestinal movements and there is now evidence that purines participate in many physiological contral mechanisms such as the regulation of coronary flow and myocardial function platelet aggregation and neurotransmission in both the central and peripheral nervous system
0 Comments