Increased 5‐HT₂ receptor number in brain as a probable explanation for the enhanced 5‐hydroxytryptamine‐mediated behaviour following repeated electroconvulsive shock administration to rats

Abstract

1 Following electroconvulsive shock (ECS) administration daily for 10 days there was an increase (35 %) in 5-hydroxytryptamine2 (5-HT2) receptor number in rat frontal cortex 24 h after the last ECS, compared with handled controls. A similar increase was seen after intermittent ECS administration (5 ECS over 10 days) given during halothane anaesthesia, compared with halothane-treated controls. The dissociation constant was also increased at this time. A single ECS had no effect. 2 Treatment of rats with pentylenetetrazol, p-chlorophenylalanine or a-methyl p-tyrosine during the intermittent ECS administration abolished the increase in 5-HT2 receptor binding. 3 Since enhanced 5-HT-mediated behavioural responses are seen after repeated ECS but not when the ECS is given with the drug treatments outlined above, it is suggested that ECS-induced enhancement of 5-HT-mediated behaviour results from an increase in 5-HT2 receptor number.

The effects of single and repeated electroconvulsive shock administration on the release of 5‐hydroxytryptamine and noradrenaline from cortical slices of rat brain

“…Repeated ECS results in an increase in the number of post-synaptic 5-HT2 receptors (Kellar etal., 1981;Green et al, 1983;Goodwin et al, 1984) and drugs shown to inhibit 5-HT release do increase cortical 5-HT2 receptor density in the cortex (Green et al, 1985;Gray et al, 1986). It is therefore possible that the changes seen in the current study and the 5-HT2 receptor change seen after repeated ECS are related.…”

Chronic electroconvulsive shock and 5-HT autoreceptor activity in rat brain: an in vivo microdialysis study

“…Thus, the 5-HTzA receptor-mediated hyperactivity syndrome in rats was enhanced after chronic ECS (Evans et al, 1976), a finding matched by increased binding at postsynaptic 5-HT2 receptor sites in cerebral cortex (Kellar et al, 1981;Vetulani et al, 1981;Green et al, 1983;Burnet et al, 1995). Behaviours mediated by the 5-HT1A receptor, however, were not uniformly modified by ECS.…”

Some anticonvulsant drugs alter monoamine‐mediated behaviour in mice in ways similar to electroconvulsive shock; implications for antidepressant therapy

“…In this regard it showed a similar profile to repeated ECS which enhances 5-HTmediated behaviour in mice not only when given daily but also when given 5 times over 10 days (Lebrecht & Nowak, 1980;Green etal., 1983b). A further similarity came with the observation that repeated progabide administration increased the number of 5-HT2 binding sites, since this also occurs after repeated ECS (Vetulani et al, 1981;Kellar et al, 1981;Green et al, 1983a) and data suggest that the increased behaviour response and increased in 5-HT2 receptor number are associated (Green et al, 1983a). An increase in 5-HT2 receptor number in frontal cortex after repeated progabide administration has also been reported to occur in rats (Langer et al, 1984).…”

“…Rats which appears to be responsible for the enhanced show an enhanced hyper-activity response to 5-hybehavioural response (Green et al, 1983a). droxytryptamine (5-HT) agonists whilst mice show an Mice and rats also show an enhanced locomotor increased head-twitch response (Evans et al, 1976; response to dopamine agonists (Modigh, 1975;Evans Green et al, 1977;Lebrecht & Nowak 1980;Green et et al, 1976;Deakin et al, 1981) although there does al., 1983b).…”