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Synapses.

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Presentation on theme: "Synapses."— Presentation transcript:

1 Synapses

2 Interneuronal communication
Hormone "Volume" Ephapse Juxtapositional exchange Gap junction Chemical synapse depolarisation modulation retrograde (NOS, TFs)

3 Mammalian electrical synapses
Mesencephalic n. of V Dieter's vestibular n. Inf. olive Retina Electrical coupling Uncoupled during AP

4 Classical Neurotransmitter
Contained in presynaptic terminal Synthesized in presynaptic neurone Released in response to stimulus in presynaptic neurone Elicits a response in the postsynaptic neurone

5 Neurotransmitters Amine Peptide Heterogeneous
Amino acid (Glut, Gly, GABA, Aspartatae) Monoamine Catecholamine (DA, Adr, NA) 5-HT Histamine Peptide Enkephalins, endorphins Gastrin, CCK, VIP, substance P Heterogeneous ACh, NO, CO, ATP, adenosine, D-serine

6 Synaptic receptor classification

7 Neurotransmitters

8 Gs

9 Neurotransmitters: Effects on postsynaptic membrane
Ion channel opening Depolarisation Na, Ca Hyperpolarisation K Restoration to resting Cl Second messenger Ca, cAMP, IP3 Receptor/channel regulation Phosphorylation, activation, inactivation Transcription factor activation Chemical change Structural change

10 Second Messengers Calcium Cyclic AMP Nitric oxide
Phosphodiesterase Adenylate cyclase II bg subunit activated III,IV Calcium activated V, VI Calcium inhibited Nitric oxide Inositol trisphosphate ras, fos, jun

11 Neurotransmitters: Cellular functions
Neurone Fire new AP (Na) Alter sensitivity of synapse Apoptosis Muscle Skeletal muscle contraction (Ca:troponin) Smooth muscle contraction Vascular (a) bronchus (b2) ciliary, gut , bladder (M) Cardiac leak current (heart rate, b1) Other metabolic cells Glycogenolysis Platelet aggregation Lipolysis ↑ Gastric acid

12 Synaptic modification
Desensitisation Phosphorylation by PKA bARK b-arrestin Downregulation Internalisation ↑ Degradation ↓ Synthesis Receptor structure GluR RNA editing AMPA splicing Anatomical change ? LTP

13 Neurotransmitters: Global effects in the CNS
Glutamate excitatory GABA inhibitory, epilepsy Glycine inhibitory (spinal cord) NA, 5-HT affect ACh memory, motor, vomiting DA psychosis, motor, vomiting Endorphins addiction, ↓ pain

14 Global neurotransmitter pathways
Ach DA NA Parietal Striatum Cing Frontal HT Septal n. Ventral tegmental area Amyg HC Basal forebrain n. SNPC Tegmentum Lateral tegmental n.

15 Metabo- and Ionotropic receptors

16 Presynaptic Calcium restoration
Buffering by Calmodulin Dilution Extrusion by ATPase

17 GABAA Cl-channel binding
Benzodiazepines Barbiturates Steroid Zn Picrotoxinin-TBPS Strychnine

18 NMDA receptor binding Glutamate Polyamine Zn
Glycine (essential co-agonist) Mg PCP

19 Ca excitotoxicity ODC NOS PLA2 Proteases Endonucleases
Mitochondrial damage


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