neurons that release norepinephrine as a neurotransmitter are called neurosecretory.
neurons that release norepinephrine as a neurotransmitter are called?
neurosecretory
in addition, the tcas interact with adrenergic receptors. this interaction seems to be critical for increased availability of norepinephrine in or near the synaptic clefts. actions of imipramine-like tricyclic antidepressants have complex, secondary adaptions to their initial and sustained actions as inhibitors of norepinephrine transport and variable blockade of serotonin transport. norepinephrine interacts with postsynaptic α and β adrenergic receptor subtypes and presynaptic α autoreceptors. the α receptors include presynaptic autoreceptors which limit the neurophysiological activity of noradrenergic neurons in the central nervous system. formation of norepinephrine is reduced by autoreceptors through the rate-limiting enzyme tyrosine hydroxylase, an effect mediated by decreased cyclic amp-mediated phosphorylation-activation of the enzyme. α receptors also cause decreased intracellular cyclic amp expression which results in smooth muscle relaxation or decreased secretion. tcas activate a negative feedback mechanism through their effects on presynaptic receptors. one probable explanation for the effects on decreased neurotransmitter release is that, as the receptors activate, inhibition of neurotransmitter release occurs (including suppression of voltage-gated ca currents and activation of g protein-coupled receptor-operated k currents). repeated exposure of agents with this type of mechanism leads to inhibition of neurotransmitter release, but repeated administration of tcas finally leads to decreased responses by α receptors.
serotonin–norepinephrine reuptake inhibitor
at the synapses within the ganglia, preganglionic neurons release acetylcholine, a neurotransmitter that activates nicotinic acetylcholine receptors on postganglionic neurons. in response to this stimulus, the postganglionic neurons release norepinephrine, which activates adrenergic receptors that are present on the peripheral target tissues. the activation of target tissue receptors causes the effects associated with the sympathetic system. however, there are three important exceptions:









































bullet::::1. postganglionic neurons of sweat glands release acetylcholine for the activation of muscarinic receptors, except for areas of thick skin, the palms and the plantar surfaces of the feet, where norepinephrine is released and acts on adrenergic receptors.
sympathetic nervous system