The presence of noradrenaline and adrenaline in the brain has been demonstrated by von Euler (1946) and Holtz (1950). These substances were supposed, undoubtedly correctly, to occur in the cerebral vasomotor nerves. The present work is concerned with the question whether these sympathomimetic amines, besides their role as transmitters at vasomotor endings, play a part in the function of the central nervous tissue itself. In this paper, these amines will be referred to as 'sympathin', since they were found invariably to occur together, with noradrenaline representing the major component, as is characteristic for the transmitter of the peripheral sympathetic system.A first approach to the problem of the function of cerebral sympathin was the determination of its distribution in different parts of the brain and spinal cord. Such an approach had proved fruitful in the investigation of the functional role of the enzyme system cholinacetylase (Feldberg & Vogt, 1948), the concentration of which was found to vary greatly in different regions. This had suggested that only certain neurones made use of acetylcholine as their transmitter substance. As briefly reported elsewhere (Vogt, 1952a), sympathin, too, was found to possess a specific pattern of distribution. This very fact suggests, though it does not prove, that these amines play a part in the specialized function of those regions of the brain in which their concentration is high. A detailed map of the pattern of distribution of sympathin was prepared in the dog: it forms the first part of this paper.The second part deals with changes in the concentration of brain sympathin produced by drugs and the inferences which may be drawn from such observations.Since it was known that the total amounts of sympathin in the central nervous system were very small (between 20 and 200 ng/g* according to * lng=10'g. Operations For the purpose of stimulating the cervical sympathetic trunk, dogs were anaesthetized with ether, both cervical sympathetic chains traced and cut, and both superior cervical ganglia exposed so that they could be rapidly excised later. The distal end of one of the sympathetic trunks was threaded through a fluid electrode (Collison, 1933) and stimulated with sixteen break-shocks per sec from a Lewis interrupter connected to an induction coil; 4 V were supplied to the primary coil. The responses of the pupil, lid and nictitating membrane were observed. Stimulation was carried out for periods of 5 min with intervals of 2 min for as long as good responses were obtained.Aseptic extirpation of both superior cervical ganglia for the purpose of allowing degeneration of the postganglionic sympathetic fibres to take place was done on two cats anaesthetized with ether. Recovery from the operation was uneventful.Denervation of the left adrenal was performed on a series of cats in an aseptic operation under ether. Through a midline abdominal incision the larger and lesser splanchnic nerves were severed and the first three lumbar sympathetic ganglia extirpated on the left ...

Much work has been devoted to the search for a really sensitive and specific method of detecting and estimating adrenaline and allied substances in blood. This search has gained importance in recent years because of the desire to identify the substances liberated by adrenergic nerves. These substances can only be expected to appear in very low concentrations, and sensitive and specific tests are needed for their study. This paper describes part of the search for such tests and is a continuation of the work of West (1947a, b) in this department.The most sensitive tests for adrenaline are pharmacological tests, but no single test is really specific by itself. A number of other sympathomimetic amines are known to have effects like those of adrenaline, but they can sometimes be distinguished by the method of parallel quantitative assays. If the adrenaline-equivalent of a solution is estimated quantitatively by several different methods, and the results differ significantly among themselves, adrenaline cannot be the only active substance in the solution. If the results agree among themselves, then the evidence supports the theory that the solution contains adrenaline, but its value depends on the use of pharmacological methods which vary independently in their sensitivity to drugs closely allied to adrenaline. If small changes in the molecule affect all the tests equally, then parallel quantitative assays are of little value. One of the objects of the present investigation was to discover a set of tests which would vary independently in their response to sympathomimetic amines, so that they could be used to distinguish these amines from one another.

IN a note published some time ago [Dale and Feldberg, 1934] [1932] and Plattner [1932, 1933] found that the substance present in such extracts was rapidly inactivated by fresh blood, like acetylcholine, and that the quantity present had a general correspondence to the wide differences in sensitiveness of different muscles to the stimulating action of acetylcholine. Faradic stimulation of the nerve increased the yield; but P1 attn e r associated the apparent presence of the acetylcholine in the muscle, and its increase on mixed nerve stimulation, with a "parasympathetic" innervation of the blood vessels. In the tongue, excised from a cat treated with eserine, and divided longitudinally into halves, he found that stimulation of the chorda-lingual nerve caused increase of acetylcholine in the extract from one half, while stimulation of the hypoglossal nerve did not significantly increase the yield of the other.Hess [1923], Brinkman and Ruiter [1924, 1925]

In the present paper an attempt has been made to map out, in the central nervous system of the dog, the distribution of the enzyme (or enzyme system) which synthesizes acetylcholine. It has been shown that this enzyme can be extracted from acetone-dried tissue (Feldberg & Mann, 1944) and that such extracts, when incubated aerobically, form large amounts of acetylcholine in the presence of KCI, MgCl2, choline, cysteine, citrate and adenosine-triphosphate (Nachmansohn & Machado, 1943; Nachmansohn, John & Waelsch, 1943; Nachmansohn & John, 1945;Feldberg & Mann, 1944, 1946Feldberg & Hebb, 1947). Since this method is applicable to very small amounts of tissue, it was possible to compare the enzyme concentration in various quite small regions of the central nervous system. METHODS Dissectum. The dogs were anaesthetized with ether, and bled. The brain and spinal cord were taken out as rapidly as possible. The nervous tissue was divided into several pieces and parts not immediately wanted were kept in the refrigerator whilst the dissection of the first samples was carried out. The excised samples were at once dried with cold acetone. The number of regions tested in a single experiment was limited, since care was taken that the time interval between excision of the first and the last sample did not exceed 2 hr. Samples kept in the cold for such a period did not lose much activity, certainly not more than 20%. In addition there was satisfactory agreement in control experiments in which the order of preparing the samples from different regions was varied. Samples from the tracts and horns of the spinal cord and from the region of the supraoptic nuclei were cut out with a small knife after freezing the tissue. Such freezing for a short time did not affect the ability of the tissue to synthesize acetylcholine.Details about the dissection of those regions which are macroscopically ill-defined are as follows. Samples from the cerebral cortex and cerebellar cortex were obtained by cutting off the grey matter from the underlying fibres with fine scissors. The cortical areas were identified with the help of the maps published by Klempin (1921). The region called 'cerebellar nuclei' is that part * With a grant from the Medical Research Council.

THE observation that reserpine causes a 'severe loss of 5-hydroxytryptamine from brain tissue (PLETSCHER, SHORE, and BRODIE, 1956; PAASONEN and VOGT, 1956) prompted the investigation of the effect of this drug on the noradrenaline content of brain. The region analysed was the hypothalamus, as its noradrenaline content is high and as the effect of reserpine on the 5-hydroxytryptamine of brain had been demonstrated on this region (PAASONEN and VOGT, 1956).Cats were used in which the left adrenal gland had been denervated in an aseptic operation under ether between twelve and twenty days before the experiment. This procedure allowed simultaneous observation of the noradrenaline content of the hypothalamus and of any central stimulation of the sympathetic system produced by the drug; such stimulation would appear as a difference in the amount of medullary amines (adrenaline and noradrenaline) found in the innervated and the denervated gland. The methods used have all been reported (VOGT, 1954) with the exception of the use of pithed rats (SHIPLEY and TILDEN. 1947) for some of the assays of noradrenaline and adrenaline; this preparation gives a steadier baseline than the anaesthetized rat treated with hexamethonium. Control experiments showed that small doses of reserpine, such as might be present in the brain extracts, did not interfere with the assays.The reserpine (Serpasil Ciba, ampoules of 2.5 mg/ml) was given i.p., and doses of the drug and duration of the experiments are shown in Table