Acetycholine and cholinergic receptors
Synthesis and catabolism
Choline
Acetyl-CoA
Choline acetyltransferase
Acetylcholine
Acetylcholinesterase
Choline
Acetate
Dopamine
Dopamine and it’s receptors are located mainly in central system. It is secreted by neurons that originate in the substantia nigra. The terminations of these neurons are mainly in the straital region of the basal ganglia. The effect of dopamine is usually inhibitory. There are 5 sub- types of dopaminergic receptors; D1,D2,D3,D4,D5 form.
Acetylcholinergic receptors
Muscrinic receptors (M-receptor) smooth muscle, gland and cardiac muscle Atropine Nicotinic receptors (N-receptor) motor ending-plate (N2), postsynaptic membrane(N1), N1:hexamethonium( 六烃季胺), N2:decamethonium N2:exciting skeletal muscle ,N1 exciting the postsynaptic neuron in ganglia
Dopamine
Dopamine β -hydroxylase
Norepinephrine
Norepinrphrinergic Receptors
Ther are two types of the norepinephrinergic receptors binded with norepinephrine and epinephrine.
3. released from slice of brain regions into the synaptic cleft in vitro. 4. produces effects on target neurons when applied to their membrance by mesns of a micropipette (微电泳). 5.The agonist can produce the same effects;but antagonist can block the role of transmitters.
Locations
Antagonist
inhibiting the cardiac muscle, exciting the smooth muscle & gland
Norepinrphrine
Norepinephrine Biosynthesis
Phenylalamine Tyrosine Tyrosine hydroxylase Dopa Dopa decarboxylase
Serotonin
It is secreted by nuclei that originate in the median raphe of the brain stem and projects to many brain areas, especially to the dorsal horns of the spinal cord and to the hypothalamus. Serotonin acts as an inhibitor of pain pathways in the cord, and it ia also believed to help control the mood of the person, perhaps even to cause sleep.
Criterions
A substance is a transmitter if it is 1.distributed in the synaptic knob, and its distribution parallels that it receptors in postsynptic cell, 2.There are the synthetic enzymes in presynaptic neuron and the catabolizing enzymes in the synapse.
Types
α-receptors α1 & α2
Deoxynorepinephrine
β-receptors β1,β2,β3 Isoproterenol propranonol(β) atenolol(β1) butoxamine(β2
Hale Waihona Puke AgonistAntagonist
phentolamine(α) prazosin (α1) yohimbine (α2)
Opioid Peptides
Enkephalin and endorphins They are probably secreted by nerve terminal in the spinal cord, the brain stem, the thalamus, and the hypothalamus. These probably act as excitatory transmitters to excite another system that inhibits the transmission of pain. Three opiate receptors are established: μκδ receptor