Catecholaminergic systems

Clear similarities exist between the effects of LSD and those of other hallucinogens on catecholaminergic systems. Anden et al. (5) noted that psilocybin and DMT accelerate NE turnover in the rat brain. Hallucinogens of other chemical series, notably methoxyamphetamines (e.g., DOM) (68) and THC (13), also increase the rate of synthesis and utilization of NE in brain. The increase due to THC probably involves a direct action of the drug, since an enhanced conversion of 3H-tyrosine into 3H-NE was found in synaptosomes incubated in the presence of 3 to 10 fiM THC (13). 

L-Deprenyl selectively inhibits MAO-B and increases activity in the catecholaminergic system. In an initial placebo-controlled study, no cognitive improvement was found, but studies have shown an improvement in the performance in neuropsychiatric batteries in patients taking deprenyl. More... 

Tricklebank M, Forler C, Fozard J The involvement of subtypes of the 5-HTl receptor and of catecholaminergic systems in the behavioural response to 8-hydroxy-2-(di-n-propylamino) tetralin in the rat. Eur J Pharmacol 106 271-282, 1984... 

GABA is a major CNS inhibitory neurotransmitter, which, among other effects, may attenuate catecholaminergic systems. VPA (perhaps by inhibition of this transmitter s degradation by GABA transaminase), CBZ, and lithium have all been reported to enhance GABA activity (see also the section Mechanism of Action in Chapter 12). 

The histaminergic neuronal system may interact with serotonergic and catecholaminergic systems in the regulation of PRL secretion and H3 receptors may be located presynaptically on... 

Roberts DCS, Corcoran ME, Fibiger HC (1977) On the role of ascending catecholaminergic systems in intravenous self-administration of cocaine. Pharmacol Biochem Behav 5 615-620. 

Borisova NA, Sapronova AY, Proshlyakova EV, Ugrumov MV (1991) Ontogenesis of the hypothalamic catecholaminergic system in rats synthesis, uptake and release of catecholamines. Neuroscience 43 223-229. 

Dunn AJ, Berridge CW (1987) Corticotropin-releasing factor administration elicits a stress-like activation of cerebral catecholaminergic systems. Pharmacol Biochem Behav 27 685-691. 

In addition to the effects of the proinflammatory immune response on serotonin metabolism, other neurotransmitter systems, in particular the catecholaminergic system, are involved in depression, too. Although the relationship of immune activation and the lack of catecholaminergic neurotransmission has not been well studied, the increase of the monoamino-oxidase (MAO) activity, which leads to decreased noradrenergic neurotransmission, might be an indirect effect of the increased production of kynurenine and quinolinic acid (Schiepers et al., 2005). 

Goldstein DS, Mezey E, Yamamoto T, Aneman A, Friberg P, Eisenhofer G. Is there a third peripheral catecholaminergic system Endogenous dopamine as an autocrine/paracrine substance derived from plasma DOPA and inactivated by conjugation. Hypertens Res 1995 18 Suppl l S93-9. 

Due to aging, the maximum level of activation of the CNS, via the catecholaminergic system, decreases progressively with the passing of time. The blackout ( natural death ) of the integrative work of the CNS, signaled by the disappearance of an EEG, occurs when the catecholaminergic system s abil-... 

Altogether, the data substantially support the view that natural death sets in when the catecholaminergic system s ability to activate the telencephalon sinks, for whatever reason, below a critical threshold, and during a state of emergency when a high level of activation is needed to survive the tribulation, the cortical neurons cannot reach the necessary level of activation. 

The results shown in Table 3.7 are especially apt in support of this conclusion. There are innate differences in the efficiency of the mesencephalic catecholaminergic system. For the brain of animals (nos.) 1, 2, 4, 5, and 6 the hot plate heated to 50 °C was already an adequate stimulus to enhance the excitability of the cortical neurons for escape and to survive the tribulation without perceivable consequences. Animals 3 and 7 escaped, but fell ill thereafter. Animals 8, 9, and 10 were unable to cope with the situation and died. 

A role has been suggested for polymorphisms of genes in the serotonin-ergic, dopaminergic, and catecholaminergic systems, which are associated with FM and additional comorbid conditions [26]. The polymorphisms... 

Wauquier A. Pharmacology of the catecholaminergic system. In Kales A, ed. The Pharmacology of Sleep. Berlin Springer-Verlag, 1995 116 65-90. 

In all, the reported neurochemical effects tend to confuse, rather than aid comprehension of the neurotoxicity of lead. Some effects appear to be seen in the catecholaminergic systems at relatively low doses of lead. As lead-induced changes in other major neurotransmitter systems are generally seen at moderate to high exposures, the question of what is a relevant or justifiable level of lead must again be asked. 

In the CNS a neurotoxic effect of lead on the catecholaminergic system has been reported. With respect to the catecholamines, the data point to a selective action of lead, with the midbrain and the diencephalon being prime targets. In these brak areas lead e q)o-sure results in alterations in the concentration of dopamine and in addition in a reduction in the activity of the dopamine synthesising enzyn tyrosine hydroxylase (McIntosh et al., 1989). 

Kinetic studies of the catecholamine levels in the spinal fluid would be the most direct means for exploring the function of the catecholaminergic system in the brain. However, it would be difficult in such studies to obtain repeated samples at small enough intervals of time to permit proper evaluation of the catecholaminergic system and its homeostasis. 

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