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Cholinergic involvement in the modulation of oxotremorine-tremor in mice by propranolol
Abstract:
Propranolol in low doses antagonized and in higher doses facilitated oxotremorine-induced tremor (Oxo-tremor) in mice. Atropine blocked Oxo-tremor, an effect that was reversed by propranolol. Atropine pretreatment also antagonized the potentiating effect of propranolol on Oxo-tremor. Propranolol inhibited mice brain cholinesterase at doses which enhanced Oxo-tremor. Timolol and sotalol produced a dose-dependent antagonism of Oxo-tremor, whereas practolol failed to produce a similar effect. None of these three agents produced any significant enhancement of Oxo-tremor. These results suggest the involvement of a peripheral mechanism for the antagonism and a central cholinergic mechanism for the facilitation of Oxo-tremor by propranolol.
Insights
Propranolol
Area of Science:
- Neuropharmacology
- Cholinergic system research
Background:
- Oxotremorine-induced tremor (Oxo-tremor) is a model for studying tremor.
- The role of beta-adrenergic receptors in tremor is not fully understood.
Purpose of the Study:
- To investigate the effects of propranolol, a beta-adrenergic antagonist, on Oxo-tremor in mice.
- To explore the interaction between propranolol, atropine, and the cholinergic system in modulating tremor.
Main Methods:
- Administration of varying doses of propranolol, atropine, timolol, sotalol, and practolol to mice.
- Induction of tremor using oxotremorine.
- Measurement of tremor severity.
- Assessment of cholinesterase activity in mouse brains.
Main Results:
- Low-dose propranolol antagonized Oxo-tremor, while high doses facilitated it.
- Atropine blocked Oxo-tremor, an effect reversed by propranolol.
- Propranolol inhibited cholinesterase at doses that enhanced Oxo-tremor.
- Timolol and sotalol antagonized Oxo-tremor; practolol did not.
Conclusions:
- Propranolol exhibits dual effects on Oxo-tremor, suggesting both peripheral and central mechanisms.
- Peripheral mechanisms may be involved in propranolol's antagonism of tremor.
- Central cholinergic pathways are implicated in propranolol's facilitation of tremor.