Rats and mice were given either
CsCl (3 mmol/kg, s.c.) or saline (as control), twice daily for 3 days. The administration of
tranylcypromine (TCP) (15 mg/kg, i.p.) to rats pretreated with
CsCl produced the
5-HT behavioural syndrome. Pretreatment with
CsCl also enhanced the syndrome induced by
p-chloroamphetamine (3 mg/kg, i.p.) or by TCP (15 mg/kg, i.p.) plus
L-tryptophan (50 mg/kg, i.p.).
p-Chlorophenylalanine (300 mg/kg, i.p., daily on 2 consecutive days) or (-)-
propranolol (20 mg/kg, i.p.),
pindolol (4 mg/kg, i.p.) and
ritanserin (0.4 mg/kg, s.c.), all prevented the behavioural syndrome induced by
CsCl and TCP in rats. Pretreatment of rats with
CsCl potentiated the
5-HT syndrome, elicited by the
5-HT agonists,
8-OH-DPAT (0.5 mg/kg, s.c.), 5-MeODMT (2 mg/kg, s.c.) and
quipazine (25 mg/kg, i.p.). Pretreatment with
CsCl potentiated the 5-HT2-mediated head-twitches in the mouse but had no effects on
hypothermia in the mouse induced by
8-OH-DPAT (0.5 mg/kg, s.c.). The rate of synthesis of
5-HT in the whole brain (excluding cerebellum) was enhanced by pretreatment with
CsCl. The enhancement of
5-HT neuronal function by
caesium may be related to its ability to block K(+)-channels in neuronal membranes.