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

SUMMARY1. In the avian brain, a high concentration of dopamine was found in a sharply contoured region of the nucleus basalis which may or may not have included the nucleus entopeduncularis, and therefore lay within the palaeostriatum of the nomenclature of Crosby and Huber. This was thus the only region which may be considered biochemically homologous to the mammalian corpus striatum. For purposes of macroscopic identification only, the region is described here as the 'anterior part of the nucleus basalis'. The concentration of dopamine was 3 /tg/g in the pigeon, about the same in the duck and chicken, and 7*5 ,ug/g in the finch. In the pigeon this region also contained some noradrenaline; the quantity of 5-hydroxytryptamine (1.4 ,ug/g) and 5-hydroxyindolylacetic acid (0.6 ,ug/g) was larger than in any other part of the brain.2. In the brain of the pigeon and the chicken, the highest concentrations of noradrenaline (1.5 and 1 4 ,ug/g) were found in the hypothalamus. 3. The concentration of adrenaline was higher in the avian than in the mammalian brain. In the hypothalamus, it ranged from 0 4 ,tg/g in the pigeon to 1 ,ug/g in the chicken.4. Fluorescence microscopy, using the formaldehyde condensation method, showed, in the anterior part of the nucleus basalis, a large area of diffuse green-yellow fluorescence, similar in appearance to the fluorescence of the striatum of the rat. In addition this part of the brain contained a small region of fluorescent fibres and varicosities. It is suggested that the diffuse fluorescence was produced by dopamine. It was absent from brains of reserpine-treated pigeons.5. In the pigeon, reserpine, tetrabenazine and prenylamine produced a decrease in the concentration of brain monoamines, an effect which was comparable to that seen in mammals. Yet, none of these drugs raised the * Present address: Catedra de Farmacologia Experimental, Facultad de Farmacia y Bioquinica, Buenos Aires, Argentina.A. V. JUOBIO AND MARTHE VOGT concentration of homovanillic acid, but they increased that of 5-hydroxyindolylacetic acid; these drugs raise the concentration of both acids in mammalian brain.6. In the pigeon /,-tetrahydronaphthylamine decreased the concentration of all monoamines and their metabolites, an action quite different from that produced in the mammalian brain.7. The main effect of morphine and of M99 (6,14-endoetheno-7-(2-hydroxy-2-pentyl)-tetrahydro-oripavine hydrochloride) was a lowering of the noradrenaline concentration.8. As in mammals, chlorpromazine affected only the dopamine metabolism.9. In the guinea-pig and the pigeon, the administration of a-methyl-DOPA led to a substitution of much of the cerebral noradrenaline by a-methyl-noradrenaline, sometimes in excess of the lost noradrenaline. However, although the loss of dopamine was severe in both pigeon and guinea-pig, only little a-methyl-dopamine accumulated in the pigeon brain, so that it did not consitute a replacement for the lost dopamine; in the guinea-pig, ac-methyl-dopamine was found in quantities similar to, or excee...

Reserpine causes the release of 5-hydroxytryptamine (5-HT) from all tissues in which it is normally stored. This release is shown by a fall in the tissue concentration of 5-HT and by an increase in its urinary metabolites (Pletscher, Shore & Brodie, 1955;Shore, Silver & Brodie, 1955). That reserpine may also lower the concentration of catecholamines in tissues was shown by experiments (Holzbauer & Vogt, 1956) in which the disappearance of noradrenaline from the hypothalamus was demonstrated in cats injected with small doses of reserpine (0-4 mg/kg). This depletion, however, did not occur in all organs, the denervated, in contrast to the innervated, adrenal medulla remaining unaffected by this dose of the drug.It is tempting to try to correlate the effects on behaviour and responsiveness produced by reserpine with the loss of 5-HT and noradrenaline from the brain. The tendency has been to attribute not only the sedation, but also such signs as the fall in blood pressure, the miosis and the relaxation of the nictitating membrane to central changes alone. Although all these phenomena might be due to central causes, they could also be produced, at least partly, by disturbances in the peripheral sympathetic system. Failure of another sympathetic mechanism after reserpine was described by G. M. Everett who observed (personal communication, and Everett, Toman & Smith, 1957) that cold did not produce pilo-erection in mice injected with reserpine. This failure, too, might be due to a central or to a peripheral derangement, or to both.The aim of the present paper is to determine the effect of reserpine on the peripheral sympathetic tissues: the investigation, abstracts of which have been published (Muscholl & Vogt, 1957 a, b), deals with the loss of transmitter and the damage to function produced by reserpine in adrenergic neurones. In preliminary experiments the normal range of concentrations of adrenaline and noradrenaline in various parts of the sympathetic system was established.

In 1917 Stewart and Rogoff tried to determine whether the chronically denervated adrenal medulla shows any secretory activity. They came to the conclusion that " no epinephrine is normally released except through nerves." In view of the recent development of sensitive methods for the detection of adrenaline and noradrenaline, and in view of the possible role played by noradrenaline in the maintenance of vascular tone, the problem was reinvestigated. METHODSOperations.-Ten cats were used. In a preliminary aseptic operation under ether, the larger and the lesser splanchnic nerves were cut bilaterally where they emerge from the diaphragm. In addition, both lumbar sympathetic chains were excised, from the first ganglion down to the third or fourth. The removal of the sympathetic chains ensures the section of any fibres which may enter the adrenal without first joining the splanchnic nerves (Elliott, 1913;McFarland and Davenport, 1941). Recovery from the operation was uneventful, except for an occasional transient diarrhoea. Between 17 and 56 days after the operation, the cats were anaesthetized with chloralose and adrenal blood collected after injection of heparin. In most instances, the blood was obtained from a cannula introduced into the lower end of the inferior vena cava after preliminary evisceration, bilateral nephrectomy, ligation of the aorta at the level of the renal arteries, and of the adreno-lumbar veins at the lateral border of the adrenals. The vena cava was occluded above the entry of these veins by a ligature which had frequently to be placed inside the liver tissue so as not to obstruct the flow from the right adrenal. For the purpose of arterial injections of KCl, a cannula was tied into the stump of the coeliac artery. The cannula was connected by a short piece of rubber tubing to the butt of a syringe needle. Slow infusions were made by a syringe, the contents of which could be delivered gradually by pushing its plunger with the help of a screw turning in a metal frame which was attached to the barrel. In a few animals the left adreno-lumbar vein entered the renal vein. In these cats, provided infusion into the coeliac artery was not intended, evisceration, right nephrectomy, and ligation of aorta and vena cava could be dispensed with. After removal of the left kidney, blood was obtained from the left adrenal by tying a cannula into the distal end of the left renal vein and occluding its central end.Estimations of sympathomimetic amines.-All blood samples were collected in icecooled tubes, centrifuged without delay, and small portions of the native plasma tested for adrenaline on the rat's uterus on the same day. The remaining plasma was extracted, and the amines in the extracts separated by paper chromatography and eluted from the paper. The eluates were evaporated to dryness and the residue taken up in a