<prompt> Which of the following synaptic transmitter is NOT a peptide, polypeptide or proteinSubstance PMet-enkephalinb-EndorphinSerotonin  <response>: D. i.e. Serotonin 95 - 96- Ganong 22nd 1081-82- A.K. Jain 3rd Dopamine, Norepinephrine, Epinephrine, Serotonin. Histamine are AMINES Polypeptides are - Substance P, other tachykinins, Vasopressin, oxytocin, CRH, TRH, GRH,Somatostatin, GnRH, Endothelins, 3-Endorphin, Endomorphins Enkephalins, Dynorphins,Cholecystokinin CCK-4 and CCK-8. VIP, Neurotensin, Gastrin releasing peptide, Gastrin, Motilin,Secretin, Glucagon derivatives, Calcitonin gene related peptide - a, Neuropeptide y, Activins, Inhibins,Angiotensin II. FMRF amide, Galanin, ANP, BNP, Substance P - is transmitter for afferent neurons that relay sensory information into the CNS and is though to be invoved in the transmission of nociceptive pain producing stimuli. Enkephalins and Endorphins - role in regulating pain, in eating and drinking behaviour, in central regulation of the CVS, and in cell development 