Biomedical subjects

Stephen H Butler

Publications and source records attributed to Stephen H Butler.

5 recordsLinked to original sources

PubMed2005

Does inversion abolish the left chimeric face processing advantage?

Experiments using chimeric stimuli have shown that the right hemisphere is more influential in processing facial information. Here, again, we found clear evidence that study participants used the information from the left side of the face to inform their gender decisions when chimeric male/female, female/male stimuli were presented. Most interestingly though, this effect was not only present for upright faces but also for inverted (flipped) faces (although the effect was significantly reduced). We propose that the chimeric bias effects found here argue against the idea that inversion destroys the right hemisphere superiority for faces. If this was indeed the case, flipping the chimeric faces should have resulted in a loss of the left face bias. This was not the case.

Adult↗

PubMed1992

A limited arthritic model for chronic pain studies in the rat.

Freund's adjuvant induced polyarthritis in rats has been used extensively to study pain processes of long duration. There are limitations of this model for chronic studies of pain/arthritis since the severe systemic changes provoke ethical concerns and also affect behaviour, physiology and biochemistry. Attempts to limit adjuvant-induced arthritis by plantar injection of the inoculum have been made. In this model, however, the process evolved to produce widespread polyarthritis if followed for the 6-plus-weeks necessary for chronic studies. Therefore, although it offers the researcher a reliable limited model of inflammation and nociception at the outset, for longer studies it may have all the disadvantages of the polyarthritic rat. The purpose of the present study was to produce a limited arthritic process in rats, stable over 6 weeks and suitable for behavioural and neurochemical studies of various chronic pain treatment methods. Injection (0.05 ml) of complete adjuvant containing 300 micrograms Mycobacterium butyricum in the tibio-tarsal joint produces a predictable monoarthritis, stable clinically and behaviourly from weeks 2 through 6 post injection. As revealed by clinical observations and X-ray examinations, the arthritis produced was limited anatomically, pronounced, prolonged and stable. A marked increase in sensitivity to paw pressure was seen in the affected limb. Animals gained weight and remained active, indicating little systemic disturbance as opposed to polyarthritic rats. We propose this limited model of arthritis as a suitable alternative to the polyarthritic rat for prolonged studies.

Animals↗

PubMed1986

Do acute or chronic tricyclic antidepressants modify morphine antinociception in arthritic rats?

In a chronic pain model, the arthritic rat, tricyclic antidepressants (TCAs) have been shown to clearly reduce behavioural signs of nociception. In the present work, using a test of acute nociception (vocalization threshold to graded foot pressure) in the same model, we evaluated the possible potentiation of morphine analgesia by 2 TCAs: amitriptyline (AMIT) and imipramine (IMIP). Using this test of acute nociception, we failed to demonstrate any analgesic effect of AMIT or IMIP given either acutely or chronically. We also failed to demonstrate any potentiation of morphine by these compounds. On the contrary, we found a significant decrease of morphine antinociception after acute AMIT administration and a tendency towards diminution with both TCAs given chronically. These results appear to temper enthusiasm for human application of this combination. They also indicate that careful further studies in a chronic pain model using behaviour evaluations are necessary before definite conclusions can be drawn concerning TCAs/opiate interaction.

Amitriptyline↗

PubMed1985

Reduction of arthritis and pain behaviour following chronic administration of amitriptyline or imipramine in rats with adjuvant-induced arthritis.

Tricyclic antidepressants (TCAs) are used extensively to treat chronic pain in man without an adequate explanation for their activity. The purpose of the present study was to investigate this problem by testing the effect of chronic TCAs in an animal pain model: the arthritic rat. Sprague-Dawley rats with adjuvant-induced arthritis were injected daily for 4 weeks with amitriptyline (10 mg/kg) or imipramine (10 mg/kg) or saline, beginning 21 days after the induction of arthritis. Baseline evaluations were made prior to the injection series and at 4 weeks, 24 h after the last injection. Both TCAs significantly reduced 'scratching' and increased 'exploring' behaviour, without changing the response to graded foot pressure. In addition clinical signs of arthritis (ankle circumference, swelling, conjunctivitis, balanitis ...) were significantly reduced, while mobility was increased. This study shows that both amitriptyline and imipramine decrease pain behaviour and arthritis in this chronic pain model. Possible 'antiinflammatory' effects of TCAs and their eventual 'analgesic' effect will be discussed.

Amitriptyline↗

PubMed1978

Effects of doxepin on perception of laboratory-induced pain in man.

Beneficial effects have been observed in University of Washington Pain Clinic patients treated with tricyclic antidepressants, but such effects occur much earlier than predicted mood elevation. A laboratory investigation of pain perception was employed to test the hypothesis that doxepin, a tricyclic antidepressant, has analgesic properties. Healthy, normal volunteers were tested over a 4-week period during which they repeatedly performed Sensory Decision Theory tasks while undergoing painful dental stimulation. Doxepin and a placebo were administered after baseline measurement for 4 weeks under double blind conditions. No significant changes due to drug administration were observed in detection threshold or sensory sensitivity indices, but response bias against reporting the stimuli as painful changed dramatically after subjects began ingesting capsules. This effect was evident in both drug and placebo groups, and it was maintained across repeated weeks of testing. These observations suggest that the instructions given patients when the drug is administered have a profound effect on pain report.

Adult↗