The Effect of Ambient Temperature on the Actions of Tremorine on Body Temperature and on the Concentration of Noradrenaline, Dopamine, 5‐hydroxytryptamine and Acetylcholine in Rat Brain

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In rats the effect of drugs on oxotremorine tremor and oxotremorine‐induced increase in brain acetylcholine has been investigated. Reserpine, (±)‐α‐methylmetatyrosine and diethyldithio‐carbamic acid, drugs which have in common the ability to decrease tissue noradrenaline concentration, inhibited oxotremorine tremor without preventing the oxotremorine‐induced increase in brain acetylcholine. (±)‐p‐chlorophenylalanine, a depletor of tissue 5‐hydroxytryptamine, did not inhibit oxotremorine tremor. Phenoxybenzamine and propranolol inhibited oxotremorine tremor, and propranolol was without effect on oxotremorine‐induced increase in brain acetylcholine. The toxicity of oxotremorine was increased by reserpine and phenoxybenzamine. The significance of these findings is discussed with regard to the mode of action of oxotremorine.

Section: Brain Acetylcholine Estimationmentioning

confidence: 99%

Effects of drugs on tremor and increase in brain acetylcholine produced by oxotremorine in the rat

Cox

Potkonjak

1970

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“…The estimate of the concentration of dopamine in the rat brain obtained by the present method is comparable with the values found by other authors. Carlsson (1959) reported a concentration of 0-60 ,ug/g and Cox & Potkonjak (1967) found a concentration of 0-87 ,ug/g in this tissue. The present value for the concentration of noradrenaline is lower than that given in -these reports and possibly reflects a lower recovery of the endogenous noradrenaline.…”

Section: Discussionmentioning

confidence: 75%

A method for the estimation of the catecholamines and their metabolites in brain tissue

Crawford

Yates

1970

A method is described whereby the catecholamines, their precursors and metabolites may be estimated in the same brain sample. The method, outlined below, was rigorously tested in pure solution before being applied to the estimation of the catechol and methoxyamines in extracts of rat brain. (i) The brain tissue was homogenized in perchloric acid and the perchloric acid removed as its insoluble potassium salt. (ii) The acid metabolites of the amines were extracted from the acidified extract into ethyl acetate. (iii) After extraction with ethyl acetate, the aqueous extract was treated with acetic anhydride and sodium hydrogen carbonate and the acetylated derivatives of the amines extracted into dichloromethane. (iv) The aqueous solution remaining after extraction with dichloromethane contains the acetylated amino‐acids. Acetyl‐dopa could be extracted into dichloromethane only after acidification of this aqueous solution. The acetyl‐dopa in this dichloromethane extract could be estimated fluorimetrically. (v) The dichloromethane extract containing the acetylated amines was chromatographed on paper in the organic phase of a mixture of toluene: ethyl acetate: methanol: water, 10: 1: 5: 5. (vi) The acetylated amines were eluted and estimated fluorimetrically. A new method was developed for the estimation of 3‐methoxytyramine and its acetylated derivative. The reproducibility of the method was demonstrated by the consistent estimates obtained for the concentrations of noradrenaline, dopamine and 3‐methoxytyramine in whole rat brain. Adrenaline and metanephrine were not detected. The concentration of normetanephrine in rat brain was at the limit of detection of the method. Although the estimation for the levels of endogenous amines in whole rat brain were consistent, the recoveries of exogenous amines taken through the procedure were low and very variable. Control experiments demonstrated that the exogenous amines were lost at the perchloric acid extraction stage of the procedure.

“…The clinical features of tetrabenazine tremor are similar to the tremor induced by tremorine, but there are important differences. Tremorine tremor is suppressed by atropine or hyoscine (Everett, 1956;Spencer, 1965) and it is not influenced by warming rats or mice in ovens at 36°-38°C (Blockus & Everett, 1959;Cox & Potkonjak, 1967). Furthermore, tremorine tremor is usually accompanied by excitement, in contrast to the sedation associated with tetrabenazine tremor.…”

Section: Discussionmentioning

confidence: 99%

Tremor induced by tetrabenazine

Calne¹,

Webster²

1969