Adrenaline and Noradrenaline

Abstract

Noradrenaline and adrenaline are catecholamines that play major roles in regulation of the ‘inner world’ of the body by the brain. Noradrenaline (synonymous with norepinephrine), the main neurotransmitter of the sympathetic nervous system, is responsible for tonic and reflexive changes in cardiovascular tone. Adrenaline is a key determinant of responses to metabolic or global challenges to homeostasis, such as glucoprivation, and of manifestations of emotional distress. In contrast with the view that the sympathetic nervous and adrenomedullary hormonal systems function as a unit (the ‘sympathoadrenal system’) to maintain homeostasis in emergencies, across a variety of situations adrenaline responses are more closely linked to responses of the hypothalamic‐pituitary‐adrenocortical system than of the sympathetic nervous system. The sympathetic noradrenergic system is active even when the individual is at rest and maintains tonic levels of cardiovascular performance. Adrenoceptors in the membranes of effector cells determine the physiological and metabolic effects of catecholamines. Key Concepts: Noradrenaline and adrenaline are catecholamines. Noradrenaline is the main neurotransmitter of the sympathetic nerves in the cardiovascular system. Adrenaline is the main hormone secreted by the adrenal medulla. The sympathetic noradrenergic system plays major roles in tonic and reflexive changes in cardiovascular tone. Adrenaline is a major determinant of responses to metabolic or global challenges to homeostasis. Adrenaline responses to stressors are more closely linked to responses of the hypothalamic‐pituitary‐adrenocortical system than of the sympathetic nervous system. The sympathetic noradrenergic system is active even when the individual is at rest and maintains tonic levels of cardiovascular performance. Adrenoceptors in the membranes of effector cells determine the physiological and metabolic effects of catecholamines. Beta‐adrenoceptors mediate stimulatory effects of catecholamines on the rate and force of the heartbeat; stimulation of vascular alpha‐adrenoceptors produces vasoconstriction and increases blood pressure, and stimulation of vascular beta‐adrenoceptors – especially beta‐2 adrenoceptors in skeletal muscle – produces vasodilation. Catecholamines affect cardiovascular functions by actions at adrenoceptors on cardiovascular cells, in the nervous system, and in the kidneys.

Zebrafish Larvae as a Behavioral Model in Neuropharmacology

“…We performed a light-dark locomotion test in which zebrafish larvae at 5 dpf were exposed to two known neuroactive compounds—adrenaline and tricaine. Adrenaline is a non-selective agonist of adrenergic receptors acting as a main neurotransmitter in the autonomic nervous system [105]. Tricaine is a local anesthetic that is specifically used to induce anesthesia and euthanasia in fish.…”

Deep transcranial magnetic stimulation in combination with skin thermography in obesity: a window on sympathetic nervous system

“…For these reasons, EPI response is more closely linked to responses of the hypothalamic-pituitary-adrenocortical system than of the SNS. Norepinephrine is the main neurotransmitter of the SNS; it is responsible for tonic and reflexive in cardiovascular tone [48]. Norepinephrine preferentially stimulates α1-and α2-adrenoceptors, located on vascular smooth muscle cells, by eliciting vasoconstriction, and influencing blood flow, blood pressure, and consequently, body temperature in the extremities of the body [49][50][51][52].…”

“…Catecholamine-induced thermoregulation may result not only from the peripheral vasomotor activity by NE action on α-adrenoceptors, but also from the lipolytic effect of β-adrenoceptor agonism. Plasma increased catecholamine levels might increase resting energy expenditure, participating in maintaining body weight [48]. In this connection, BAT is the main responsible of non-shivering thermogenesis in humans and is deeply innervated by sympathetic fibers reaching their β3-receptors [56].…”

Exploring the Role of Neurotransmitters in Multiple Sclerosis: An Expanded Review

“…NE, a catecholamine, is the main neurotransmitter of the sympathetic nervous system. 98 NE can regulate the activities of neuronal cells and is involved in the regulation of immune responses, neuroplasticity, inflammation, rapid modulation of cortical circuits and cellular metabolism. 99 NE exerts its effects by binding to G-protein-coupled αand β-adrenergic receptors (ARs).…”