Rate of Compulsive Circling in Relation to Accumulation of Cerebral Acetylcholine*

5,5′‐Dihydroxy‐4,4′‐Bitryptamine: A Potentially Aberrant, Neurotoxic Metabolite of Serotonin

“…Although analyses of specific brain parts were not performed, the initial increase in ACh and 5-HT levels presumably occurs predominantly in the left hemisphere into which DHBT was administered. This correlates well with the contralateral circling observed during the initial 30 min following drug administration (Aprison, 1958). The initial rise in Ch concentrations that accompanies elevated levels of ACh suggests that DHBT potentiates the synthesis, release, and catabolism of ACh and, perhaps, inhibits the high-affinity reuptake of Ch.…”

Acetylcholine Content of Discrete Areas of the Brain Obtained by a Near‐freezing Method*

“…These data and those of MITCHELL (1963) indicate that the ACh level varies inversely with the degree of functional activity of the brain. However, in studies where AChE inhibitors are used, changes in behaviour can be shown to be correlated with elevated brain ACh levels in rabbits exhibiting compulsive turning movements (APRISON and NATHAN, 1957;APRISON, 1958). Although this condition might appear contradictory to other findings, it can be explained if, in the case of the animals showing compulsive turning, the increased ACh is in the free or immediately available form (APRISON, 1958) whereas in the anaesthetized animals the elevated ACh is in the potentially available bound (labile) form (KUROKAWA et al, 1963).…”

Biochemistry of the Avian Central Nervous System—i

“…Neurohumoral agents apparently exert their effects on the behaviour as well as on other physiological functions of living organisms. Some studies have already been published in which changes in ACh levels (APRISON, 1958) or serotonin levels (APRISON et al, 1962) in the brain have been correlated with quantitatively measured behavioural changes: Magnitude and duration of the behavioural effects produced by these agents must be related in part to the activities of the endogeneous synthesizing and degradative enzyme systems. The enzyme 5-hydroxytryptophan decarboxylase synthesizes 5-HT.…”