The role of dopaminergic systems in γ-hydroxybutyrate-induced electrocorticogram hypersynchronization in the rat

Abstract

The effects of dopaminergic agonists and antagonists on the duration of hypersynchronization induced in the electrocorticogram (ecog) by γ‐hydroxybutyrate (γ‐HB) were tested in rats. Apomorphine (0·2–8 mg kg−1), piribedil (2·5–10 mg kg−1) and haloperidol (0·5–1 mg kg−1) had no influence on the duration of the hypersynchrony. Amphetamine (1·5–6 mg kg−1) inhibited the hypersynchrony, while (3,4‐dihydroxyphenylamino)‐2‐imidazoline (DPI; 5, but not 1, mg kg−1) prolonged its duration. The lack of effect of the dopamine receptor agonists apomorphine and piribedil, and the dopamine receptor blocker haloperidol, on the γ‐HB‐induced hypersynchrony might indicate that the inhibition of the impulse flow in the nigrostriatal dopamine system by γ‐HB is not involved in the generation of the hypersynchrony. DPI is thought to be an agonist at a dopamine receptor not sensitive to apomorphine, and its facilitatory effect on γ‐HB‐hypersynchrony can be interpreted in terms of a possible involvement of another dopamine system in the ecog hypersynchrony induced by γ‐HB. The antagonism of γ‐HB by amphetamine is possibly due to an indirect stimulatory effect on noradrenergic receptors.

The effects of the combined administration of gamma-hydroxybutyrate and diazepam on sleep parameters in the rat

“…Our results confirm earlier work showing that acutely administered GHB behaves as an hypnotic in the rat (Godschalk, Dzoljic, and Bonta, 1977). Regarding diazepam, SWS values were not significantly different from control.…”

“…Gamma-hydroxybutyrate (GHB) is chemically related to GABA and has often been assumed to act as a direct or indirect GABA agonist (And~n and Stock, 1973;Carlsson, Biswas, and Lindqvist, 1977). GHB crosses the blood-brain barrier and induces slow wave and REM sleep (Jouvet, Cier, Mounier et al, 1961;Matsuzaki, Takagi, and Tokizane, 1964;Godschalk, Dzoljic, and Bonta, 1977). Regarding the benzodiazepines (BZD), there is at present evidence indicating that their muscle relaxant, anticonvulsant and ataxic actions may be mediated by a &ange in the function of GABA-ergic neurons (Costa, Guidotti, Mao et al, 1976;Haefely, 1978).…”

Gamma-Hydroxybutyrate Treatment of Schizophrenia: A Pilot Study

“…Snead et al (1976) reviewed the correlations between blood and CSF levels and seizure activity on EEG in cats. Similar EEG patterns were noted in rats (Godschalk et al, 1977).…”