Studies on the biochemical and behavioural effects of oral nicotine.

The acute intragastric and chronic oral administration of nicotine had no effect on plasma corticosterone levels although both procedures induced tolerance to the stimulatory effects of acute subcutaneous nicotine (0.4 mg/kg) on corticosterone secretion. Chronic oral nicotine (5.4 mg/kg/day) also had little effect on brain 5-hydroxyindoles and no changes in plasma corticosterone or brain 5-hydroxyindoles were seen in response to nicotine withdrawal. Oral nicotine was not an adequate substitute in rats made behaviourally dependent upon nicotine injections. It is concluded that route of administration greatly influences the biochemical and behavioural properties of nicotine.