THE EFFECTS OF α‐METHYL DERIVATIVES OF NORADRENALINE, PHENYLETHYLAMINE AND TRYPTAMINE ON THE CENTRAL NERVOUS SYSTEM OF THE CHICKEN
Year: 1965
Type: article
Abstract: The mammalian central nervous system contains noradrenaline (Vogt, 1954) and 5-hydroxytryptamine (Amin, Crawford & Gaddum, 1954), but study of the possible central functions of these amines poses particular problems.One of these is that paren- terally injected amines may elicit a central effect by a peripheral action.For example, behavioural and electrocortical arousal is produced not only by amphetamine, which readily penetrates to the brain, but also by catechol amines, which do not readily cross the blood-brain barrier.Although the central nervous system is clearly involved in both instances, the similarity in effect does not indicate whether the primary action of the amine is central, peripheral or both.Indeed, if the blood-brain barrier is circum- vented and an apparently potent excitant, such as adrenaline, is given intracisternally (Leimdorfer, 1950) or intraventricularly (Feldberg & Sherwood, 1954) sleep or sedation ensue.With the mode of action of drugs on cerebral function uncertain, it is not surprising that investigation of central receptor mechanisms has yielded conflicting results.Thus the electrocortical alerting evoked by catechol amines has been attributed on the one hand to an action on central nervous catechol amine a-receptors (Goldstein & Muftoz, 1961) and, on the other, to an action mediated through cardiovascular a-receptors (Capon, 1960).The behavioural effects of catechol amines are thought to be determined predominantly through central nervous a-receptors (Wurtman, Frank, Morse & Dews, 1959; Dews, 1962).Munioz & Goldstein (1961) considered that the excitant effects of amphetamine were also mediated through central nervous a-receptors.Vane (1960), however, showed that amphetamine acted on tryptamine receptors in the smooth muscle of the rat stomach and suggested that a similar action might take place in the brain.Additional emphasis in this direction was provided by the observation that monoamine oxidase inhibitors, which potentiate central excitants, lead to different effects on the excretion of the enzyme substrates in the urine, since the concentration of tryptamine showed much the greatest increase compared with that of 5-hydroxytryptamine and the metanephrines (Dewhurst, 1961).Any examination therefore of the actions of sympatho- mimetic amines on the central nervous system should include tests of the effects of tryptamines.
Authors: W. G. DEWHURST, E. MARLEY
Institution: Maudsley Hospital
Language: English
Subfield: Cellular and Molecular Neuroscience
Field: Neuroscience
Domain: Life Sciences
Open Access status: bronze
OpenAlex ID: W2004759375