EFFECTS OF SINGLE AND REPEATED INJECTION OF METHAMPHETAMINE ON THE TISSUE CATECHOLAMINE OF RABBIT
1964 Volume 14 Issue 1 Pages 56-62
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1964 Volume 14 Issue 1 Pages 56-62
The main pharmacological effects of methamphetamine are the psychomotor stimulation and the sympathomimetic effects on the peripheral adrenergic structures. There is evidence which indicates the facilitatory action of amphetamine on the synaptic transmission (1). By increasing the dose of amphetamine the inhibitory action and the reversal of facilitation have been demonstrated in the synaptic transmission of severalparts of the central nervous system (2). It has been emphasized by many authors that the central actions of various sympathomimetic amines probably are not related to their peripheral sympathomimetic actions.
It is possible that methamphetamine acts on the adrenergic system directly, and indirectly through interference with the metabolism of endogenous catecholamine or through liberation of the latter from local sites of storage. Analyzing the dose-response curves of the normal, the denervated, the cocainized and the reserpinized nictitating membrane of cat, Burn and Rand (3) have classified the sympathomimetic amines into following two groups, i.e. the sympatomimetic amines with direct action, and those with indirect action. They have shown that amphetamine exerts its adrenergic effects indirectly through liberation of noradrenaline from the target organs. The liberation of noradrenaline from the central nervous system as well as the peripheral adrenergic structures has been confirmed biochemically by several investigators.
This experiment was designed to study whether the systemic administration of methamaphetamine depletes noradrenaline in the central nervous system of rabbits to the same extent that it does in the autonomic structures such as heart, adrenal glands.
Further, the effects of the repetition of the injection on the level of noradrenaline or adrenaline in these structures were studied since the repetitive administration of the drug is known to produce tachyphylaxis in the autonomic structures.
