Effects of ascorbate on a dopaminergic response: apomorphine-induced modification of pentylenetetrazol-induced seizures in mice.

The threshold for pentylenetetrazol (PTZ)-induced clonic seizures is below control levels 15 min after administration of apomorphine (APO) but above them 60 min after APO administration. Pretreatment with ascorbic acid (10 mg/kg) or the presence of ascorbic acid in the APO solution (1 mg/ml) inhibited the early (15 min) decrease in seizure threshold caused by 60 mg/kg APO and reversed the increase in seizure threshold 60 min after a 50 mg/kg APO challenge. Ascorbate co-administration concomitant with APO also counteracted the increase in seizure threshold 60 min after 70/kg APO. Results suggest a potential model for modulation of a seizure system through dietary supplementation.

Plasma levels of apomorphine following intravenous, intraperitoneal and oral administration to mice and rats.

Clinical use of the potent dopaminergic partial-agonist apomorphine (APO) in a wide variety of neuropsychiatric disorders is hampered by a lack of data concerning tissue/plasma levels following various routes of administration. In the present experiments, plasma levels were assessed at various times up to 4 hours after APO administration IV, IP, and PO to mice and rats. Plasma levels of total radioactivity after PO administration of [3H]-APO were 50 to 65% of those seen after IV administration, but brain levels were almost undetectable after PO administration. Organic solvent-extractable concentrations of tritium-labelled material after IV and IP administration of [3H]-APO to mice were significantly lower than the levels of total radioactivity, while after PO administration, these concentrations were minimal. Similar results were observed in rats following IV and PO administration of [3H]-APO.