ABSTRACT
The Sympathetic nervous systems (SNS) is an efferent division of the
Autonomic nervous system (ANS) with neurons which anatomically originates in
the central nervous system (CNS). It has a short preganglionic neuron which
comes from the thoracic and lumbar regions (T1 to L2) (also termed,
thoracolumbar outflow) of the spinal cord. The axons of the postganglionic
neuron extend from these ganglia to the tissues that they innervate and
regulate. In most cases, the preganglionic nerve endings of the sympathetic
nervous system are highly branched, enabling one preganglionic neuron to
interact with many postganglionic neurons. This arrangement thus enables this
division to activate numerous effector organs at the same time (Whalen, 2015). The activities of the SNS are initiated at the
effector organs by the binding and stimulatory actions of specific
neurotransmitter chemicals which are released by exocytosis at the presynaptic
terminals of neurons. The transmitter released by all preganglionic sympathetic
neuron except those supplying the sweat gland is Noradrenaline (NA). The
preganglionic sympathetic neuron supplying the sweat gland is Acetylcholine (Ach). The activities
(effects) initiated by the SNS are predominantly under the control of α2-adrenargic receptors and prostaglandin
E-series.
TABLE OF CONTENT
1.0 INTRODUCTION:…………
1.1 Sympathetic Nervous System (SNS)…………………….
1.2 SNS Activities………………………………………………………
1.3 Transmitters Of SNS……………………………………………
2.0 PRESYNAPTIC RECEPTORS………………………
3.0 CONTRIBUTIONS OF PRESYNAPTIC α2-ADRENERGIC
RECEPTORS TO THE CONTROL OF SYMPATHETIC NERVOUS ACTIVITY……………….
3.1 α2–Adrenergic
Receptor…………………………………………
3.2 Signal
Transduction Pathway Of α2-Adrenernoceptor Regulation Of SNS…
3.3 Neurotransmitter
(Noradrenaline) Release…………
3.4 Involvement
Of The Membrane Na+-K+-ATPase In The Modulation Of Norepinephrine
Release Through Presynaptic Inhibitory α2-Adrenergic Receptors…………………………………………………………
3.5 Influence
Of Neuronal Uptake Of Noradrenaline On Negative Feedback Mechanism Mediated By
Presynaptic α 2- Adrenoceptor…………………………
3.6 Presence
Of Presynaptic Inhibitory α2 –Adrenoceptors In The Brain…………
3.7 Physiological
Significance Of Negative Feedback Mechanism Mediated By Presynaptic α 2 –Adrenoceptors………………………………………………………………
3.8 Mechanism
Of Action Of α 2-Adrenergic Receptors In The Release Of Na…
3.9 Molecular
Evidences Of The Role Of α 2—Adrenergic Receptors In The
Release Of Na……………………………………………………………………………………
4.0 CONTRIBUTIONS OF PROSTAGLANDIN TO THE CONTROL OF
SYMPATHETIC NERVOUS ACTIVITY………………………………………
4.1 An
Overview Of Prostaglandins…………………………………………………………….
4.2 Prostaglandin Receptors…………………………………………………………………
4.3 Prostaglandin E Synthase………………………………………………………………………
4.4 Prostaglandins
E2 Receptors………………………………………………
4.5 Some Sympathemometic Effects Of
Prostaglandins E2 Series…………………
4.6 Presynaptic Inhibition Of
Noradrenergic Neurotransmission By Prostaglandins E Series…………………
4.7 Actions Of Pg E-Series On Adrenergically Innervated
Tissues…………………
Diminished Vasoconstrictor
Spleen:-………………………………………………………
Chronotropic And Inotropic
Responses To Sympathetic Nerve:-………………
Vascular Beds:-………………………………………………………………………………………
PGE Inhibit Twitch Response To Nerve
Stimulation:………………………………..
Enhancement Of Synaptic Transmission………………………………………………….
Hippocampus…………………………………………………………………………………………
5.0 SUMMARY/CONCLUSION……………………………………………………….
REFERENCES……………………………………………………….