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Biomedical subjects

H Cappell

Publications and source records attributed to H Cappell.

52 records · Page 3Linked to original sources
PubMed1972

Amphetamine and conditioned 'anxiety'.

1. Rats pressed a bar for milk reward at a steady rate, but this baseline responding was suppressed in the presence of an auditory stimulus associated with electric shock (conditioned suppression). The effects of (+)-amphetamine sulphate on this conditioned suppression were studied in two experiments.2. (+)-Amphetamine sulphate (0.5, 1.0 or 2.0 mg/kg) reduced the baseline rate of responding and also reduced the conditioned suppression, i.e. responding in the presence of the auditory stimulus was partially restored. Both these effects were dose related.3. In a further experiment the effects of 1.0 mg/kg on two levels of conditioned suppression were studied. Regardless of its degree, (+)-amphetamine attenuated suppression.4. The results were compared to previous research which found that amphetamine increased baseline responding and exaggerated conditioned suppression. It was concluded that the conditioned suppression procedure should be used with caution as an animal model of anxiety in psychopharmacological investigations.

Amphetamine↗
PubMedDate not supplied

Antagonism of morphine-induced aversive conditioning by naloxone.

In Experiment 1, 4 doses of morphine and 4 doses of naloxone were tested for their ability to induce a conditioned aversion to saccharin in rats. Morphine was much more potent than naloxone which had only weak effects at the highest dose (12.96 mg/kg). Based on the determinations of Experiment 1, doses of 0.096, 0.96 and 0.6 mg/kg of morphine in a second experiment. The highest dose of naloxone was an effective antagonist of morphine-induced aversion. The antagonism was incomplete, but this may have reflected the particular dose combinations that were employed. Although 12.96 mg/kg of naloxone induced only a weak conditioned aversion to saccharin in Experiment 1, 9.6 mg/kg had a substantial effect in Experiment 2. Thus naloxone was itself an agent of aversive conditioning at a dose which significantly antagonized the aversive effects of morphine. Because of the successful demonstraion of antagonism, it was suggested that there may be common pharmacological mechanisms involved in both positive reinforcement and aversive conditioning by drugs of the opiate class.

Animals↗
PubMedDate not supplied

A randomised, double-blind study of cicaprost, an oral prostacyclin analogue, in the treatment of Raynaud's phenomenon secondary to systemic sclerosis.

Cicaprost is a new synthetic prostacylin analogue which is metabolically stable and bioavailable after oral administration; in previous studies it has been shown to have vasodilator antiplatelet effects. In this pilot study, we investigated the clinical efficacy of and patient tolerance to two dosage levels of cicaprost (2.5 micrograms tds and 5 micrograms tds) in the treatment of Raynaud's phenomenon secondary to systemic sclerosis (SSc). This was a three centre, double-blind, placebo controlled study of 49 patients carried out over four winter months. For a period of 10 days, 16 patients were given a placebo, 16 received cicaprost 2.5 micrograms tds and 17 received cicaprost 5 micrograms tds. Response was assessed based on the total number and duration of Raynaud's attacks, the average severity of the attacks, the number of painful attacks as a proportion of all attacks, a digital ulcer count, and the patients' opinion of the treatment. Although the clinical and laboratory parameters of digital vasospasm did not show statistically significant improvement in those who received cicaprost compared with those on the placebo, the severity of attacks lessened in the patients who received cicaprost 5 micrograms tds, and a statistically significant difference was seen in the average severity at week 2 post-treatment (p = 0.02). The apparent lack of overall significance was probably related to the short treatment period and relatively low doses of cicaprost used in this exploratory study. Longer studies with dose titration are probably needed to demonstrate the beneficial effects, if any, of cicaprost in patients with Raynaud's secondary to SSc, and these are being planned.

Administration, Oral↗