Eugene L. Bliss

Chemical, electron microscopic and physiological observations on the role of catecholamines in the carotid body

Abstract Chemical determinations revealed large amounts of dopamine, noradrenaline and adrenaline, in the carotid body of the cat. The cathecholamine (CA) content of normally innervated and chronically synmpathectomized carotid bodies was essentially the same. It did not change by vigorous and prolonged carotid body stimulation either in situ or in vitro . High doses of reserpine reduced appreciably the noradrenaline content of the carotid body; the contents of dopamine and adrenaline also were reduced but to a lesser degree. Electron microscopy shoed the presence of numerous dense-cored vesicles in the glomus cells of the carotid body; these vesicles occurred only rarely in the capsular cells and in the carotid nerve terminals. No detectable change in the vesicular content, appearance or distribution was induced by prolonge dhypoxia, reserpinization, adrenalectomy or chronic section of the carotid nerve or sympathetic supply. Acute and chronic reserpinization of cats did not change the sensitivity and reactivity of carotid bodies (either in situ or in vitro to ACh, anoxic or asphyxic stimulation. In vitro , high doses of adrenaline, noradrenaline, dopamine, dl -DOPA and tyramine failed to produced chemoreceptor excitation or marked depression of the chemosensory discharges. The lack of effect of CA on chemoreceptor activity was not changed by reserpinization or inactivation of monaminoxidase with nialamide. Prolonged superfusion with dischloroisoproterenol, a β-adrenergic blocking agent, reduced chemoreceptor discharges by inducing nerve block. It is concluded that CA contained in the carotid body do not play a significant role in the generation of the chemosensory discharges.

Relationship of stress and activity to brain dopamine and homovanillic acid.

Abstract Levels of dopamine in the brain tend to remain stable when rodents are stressed. However, these constant values do not reflect the dynamic state. It could be shown that the metabolism of dopamine is accelerated by a variety of behaviors. Emotionally disturbing experiences, either when they are accompanied by augmented activity or when they are unassociated with it, will increase the metabolism of dopamine. In turn an increase in activity in the absence of stress will accelerate the metabolism of dopamine. It was concluded that both activity and emotionality are associated with an activation of dopamine neurones.

Brain amines and emotional stress

Evidence is presented that emotional stress in the mouse, guinea pig, and rat are associated with 10-30 per cent decrements in brain norepinephrine. This does not appear to be primarily a function of muscular activity and is probably a neurochemical concomitant of the emotional upset. It is a generalized phenomenon that occurs in cortex, subcortex, cerebellum, hypothalamus, and brain stem, to approximately the same degree. Under these circumstances the concentration in brain of serotonin, gamma-aminobutyric acid, and dopamine remain stable. It appears that decreases of brain norepinephrine may be a component of a general response to intense, emotional distress.

Brain and testicular function.

Abstract Plasma and testicular testosterone levels can fluctuate rapidly under the influence of C.N.S. events. Both acute and chronic stress, as well as sexual satiety, will reduce testicular function in rodents whereas sexual excitation will increase it. Catecholamine and serotonin neurones appear to participate in the regulation of the pituitary-testicular system.

Changes in brain norepinephrine in self-stimulating and ‘aversive’ animals ☆

Abstract Emotionality in animals appears to reduce the concentration of norepinephrine in brain. This conclusion is further supported by studies of intracranial stimulation in rats. Self-stimulation and mechanical stimulation of ‘aversive’ animals and self-stimulators, when accompanied by behavioral evidence of emotionality, all lead to decrements in brain norepinephrine. Intracranial electrical stimulation, unassociated with emotionality, does not alter the levels of the catecholamine.