Drugs acting on the Central Nervous System
Dr.Durgaprasad.S Asst.Professor KMCIC
Neurochemical transmission
Neurotransmitters: Neurohormones: Neuromodulators: originates from nonsynaptic sites, yet influences the excitability of nerve cells Neuromediators: Substances that participate in eliciting the postsynaptic response to a transmitter Neurotrophic Factors:substances produced within the CNS that assist neurons in their attempts to repair damage
Central Neurotransmitters GABA - inhibitory neurotransmitter Receptors: GABA A GABA B Glycine: - inhibitory Local interneurons in the spinal cord & brain stem
Glutamate: excitatory neurotransmitter KA (kainate): hippocampus, cerebellum, spinal cord mediate fast depolarization AMPA (α-amino-3-hydroxy-5-methyl-4isoxazole propionic acid ) mediate fast depolarization NMDA (N-methyl-D-aspartate) -Long term potentiation Glutamate Excitotoxicity
Aspartate: Acetylcholine: Spinal cord – Renshaw cells neurons in the neostriatum,medial septal nucleus, reticular formation Dopamine: Substantia nigra to the neostriatum Ventral tegmental region to the limbic cortex D1 – D5
Norepinephrine: hypothalamus , limbic system enhances excitatory inputs by both indirect and direct mechanisms Attention and arousal α1, α 2, and ß 5-Hydroxytryptamine :neurons in the raphe or midline regions of the pons and upper brain stem 5HT1 5HT2 5HT3 5HT4
Histamine :ventral posterior hypothalamus regulate arousal, body temperature, and vascular dynamics H 1 H2 H 3 H 4 Peptides:enkephalins, endorphins, neurotensin, substance P, somatostatin, cholecystokinin, vasoactive intestinal polypeptide, neuropeptide Y, and thyrotropin-releasing hormone Diffusible Mediators NO Arachidonic acid
ACTIONS OF DRUGS IN THE CNS CNS Depressants CNS Stimulants Drugs that selectively modify CNS function