tabernanthine and Hypoxia

The effects of tabernanthine on serotonin (5-HT) levels were determined in several brain areas of rats exposed to various simulated altitudes (1800, 5200, 7000 m). The 5-HT synthesis inhibitor, para-chlorophenylalanine (PCPA), was used to dissociate the effects occurring at synthesis and release levels. Tabernanthine antagonized the decrease in hypothalamic 5-HT levels induced by a 7000 m hypoxia and also suppressed the decrease in PCPA-induced depletion observed at 5200 and 7000 m in the hypothalamus, the striatum and the rest of the brain. It was assumed that tabernanthine stimulates different steps of 5-HT metabolism. These effects, revealed by hypoxia, are related to other peripheral and central properties of this drug.

Topics: Alkaloids; Altitude; Animals; Brain; Corpus Striatum; Fenclonine; Hypothalamus; Hypoxia; Ibogaine; Male; Rats; Rats, Inbred Strains; Serotonin

Topics: Animals; Atmospheric Pressure; Brain; Hypoxia; Ibogaine; Neurotransmitter Agents; Rats; Rats, Inbred Strains

The central effects of tabernanthine on noradrenaline and dopamine turnover times were studied in the hypothalamus, the striatum and the remainder of the brain of normal and hypobaric hypoxic rats, the latter state corresponding to 5,200m (410mm Hg) and 7,000m (320mm Hg). Catecholamine cerebral level were not modified by the drug in either instance. At normal atmospheric pressure the catecholamine turnover times were slightly decreased by tabernanthine. Hypobaric hypoxia alone increased noradrenaline and dopamine turnover times by inhibiting oxygen-dependent enzymes. Tabernanthine antagonized the effect of hypobaric hypoxia especially in dopaminergic areas. Antagonism was complete at 5,200m but only partial at 7,000m. This phenomenon may be related to the stimulatory properties of the drug.

Topics: Alkaloids; Animals; Atmospheric Pressure; Brain; Catecholamines; Dopamine; Hypoxia; Ibogaine; Kinetics; Male; Norepinephrine; Rats