Catecholaminergic synapses

Reuptake through the presynaptic membrane is the major deactivation mechanism for serotonin. It is prevented by the tricyclic antidepressants (see section 4.3.7), among which the tertiary amines are more potent at serotonergic terminals than are the secondary bases, whereas the reverse is true for catecholaminergic synapses. 

Figure 10.4. Targets of drag action in catecholaminergic synapses. 1 and 2, the post- and presynaptic receptors 3, breakdown, in particnlar monoamine oxidase 4, the presynaptic transmitter lenptake membrane transporters 5, the vesicnlar storage transporters.

Figure 10.14. Structure (a) and mode of action of reserpine. b Reserpine inhibits vesicular accumulation of dopamine and norepinephrine by blocking the vesicular proton antiporter. c Functional consequences of reserpine action. The net effect consists in reduced activity of catecholaminergic synapses.

Figure 10.19. False transmitters that are used for antihypertensive treatment, a a-Methyldopa passes the blood brain barrier and is decarboxylated to a-methyldopamine, which upon synaptic release stimulates presynaptic 02-receptors. b Guanethidine acts on catecholaminergic synapses in the peripheral autonomous nervous system.

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