Behavioral and neurochemical effects of hydergine in rats

Effects of various (20, 40 or 80 mg/kg; intragastric instillation) doses of Hydergine (dihydroergotoxine) were studied on the self-stimulation (SS) behavior (in young and old rats with electrodes implanted in the A10 area) and also on spontaneous motor activity (SMA) and stereotypy (ST) as well as on the concentrations of norepinephrine (NE), dopamine (DA), serotonin (5-HT) and gamma-aminobutyric acid (GABA) in discrete brain areas, such as caudate nucleus (CN), pons-medulla (PM) and diencephalon-midbrain (DM) in adult rats. Following Hydergine administration, SS and SMA showed a dose-dependent increase with peak effects occurring between 80-120 min and then decreased. ST was not induced at any dose. DA and NE levels in the DM also showed a dose-dependent increase at 90 min and then sharply decreased up to 120 min after drug administration. NE in the PM and DA in the CN showed a similar pattern, but to a smaller degree. GABA in the DM and CN showed marked increases up to 120 min, while 5-HT in the PM and DM showed steady declines during the same period. Thus it appears that the behavioral stimulant effects of Hydergine may be correlated to increase in NE and DA levels, particularly in the DM.