Biomedical subjects

M J Gentle

Publications and source records attributed to M J Gentle.

At least 19 recordsLinked to original sources

PubMed2005

Effects of non-steroidal anti-inflammatory drugs on pain-related behaviour in a model of articular pain in the domestic fowl.

The optimum doses of carprofen, flunixin, ketoprofen and sodium salicylate for the treatment of inflammatory pain were determined in domestic fowl using the microcrystalline sodium urate model of articular pain. The response criteria were the changes in pain-related behaviour over 60 min commencing 1 h after an intra-articular injection of sodium urate and an intramuscular injection of a range of doses of each of the drugs. The minimum effective doses for carprofen, flunixin and ketoprofen, respectively, were 30, 3 and 12 mg kg(-1). The minimum dose for sodium salicylate ranged from 100 to 200 mg kg(-1) and did not fully restore normal behaviour.

Animals↗

PubMed2004

Substance P immunoreactive nerve fibres in the domestic chick ankle joint before and after acute urate arthritis.

Substance P immunoreactive (SP-IR) nerve fibres were identified using fluorescence immunohistochemistry and the length of the labelled individual nerve fibres was measured using confocal microscopy of whole mounts of the lateral wall of the ankle joint in 2-week-old domestic chicks. In the normal ankle there was an extensive network of SP-IR fibres in the synovial and subsynovial tissue of the joint capsule. Fours hours after injection of sodium urate into the joint space the joint was inflamed and there was a significant reduction in the labelled nerve fibres. These results demonstrate experimentally that painful gouty arthritis produces a neurogenic depletion of substance P from peripheral nerve fibres in the synovial and subsynovial tissue.

Animals↗

PubMed2003

Preliminary study of joint disease in poultry by the analysis of synovial fluid.

Samples of synovial fluid and synovial membrane were obtained from the hock joints of several groups of broilers, including lame birds and two strains of broilers raised on different feeding regimens and given different drug treatments (carprofen or placebo). There were more significant differences between the groups on the basis of the analysis of the synovial fluid samples than the synovial membrane samples. Experimental birds fed ad libitum had the highest median red blood cell counts and median ghost cell counts of all of the groups, but there were no differences between the groups in the thickness of the synovial lining cell layer or the degree of cellular infiltrate in the synovial membrane. The synovial fluid from the broilers and lame birds fed ad libitum was more turbid, suggestive of intra-articular pathology, and the large numbers of heterophils in samples from the lame birds indicated an inflammatory arthropathy. The birds fed ad libitum which were treated with carprofen had more cells in the synovial fluid than the birds given the placebo. A large number of the samples of synovial fluid from the ad libitum-fed broilers contained blood.

Animal Husbandry↗

PubMed2001

Mechanothermal nociceptors in the scaly skin of the chicken leg.

Electrophysiological recordings were made from single sensory mechanothermal nociceptive afferent fibres in dissected nerve filaments of the parafibular nerve innervating the scaly skin of the lower leg of the chicken. Two classes of mechanothermal nociceptors were identified consisting of 34 C fibres (conduction velocities 0.45-1.5 m/s, mean 1.08) and nine A-delta fibres (3-15 m/s, mean 6.34). The C fibre afferents had receptive fields which were circular or elliptical in shape and ranged in size from 1 mm in diameter to 4 x 3 mm. Thresholds to mechanical stimulation in the C fibre afferents ranged from 0.3 to 33 g (median 1.5 g) and thermal thresholds were in the range 39-61 degrees C (median 49.4 degrees C). Stimulus-response curves to thermal and/or mechanical stimulation were recorded from 28 C fibre afferents and subjected to a linear regression analysis to determine whether they were best fitted by a linear, log or power function. The results were variable and no single function provided the best fit for all the responses. Of the fibres tested with both stimulus modalities (n=17), only 12 fibres showed the same best fit for both stimuli; in the others the best fit regression lines differed between stimuli. The response of the A-delta fibres to mechanical and thermal stimulation was very similar to the C fibres but the small number of A-delta fibres precluded any detailed statistical analysis. Comparison of the physiological properties of the C fibres in the leg with those previously identified in the beak showed that those in the leg had significantly lower thermal thresholds, but higher mechanical thresholds. The possible functional significance of these differences is discussed. These findings are also discussed in a comparative context to identify similarities and differences between mechanothermal nociceptors in birds and other vertebrates, relating these to their possible evolutionary and functional significance.

Action Potentials↗

PubMed2001

Effects of anti-inflammatory steroid drugs on pain coping behaviours in a model of articular pain in the domestic fowl.

The optimum dose rates of betamethasone, dexamethasone (sodium phosphate) and methylprednisolone (acetate salt) were determined for the treatment of inflammatory pain in domestic fowl using the microcrystalline sodium urate model of articular pain. The response criteria were the changes in behavioural profiles and pain-related activity over 60 minutes commencing 1 hour after an intra-articular injection of sodium urate and a course of intramuscular injections of a range of doses of each drug on the previous 2 days. The optimum dose rates for betamethasone, dexamethasone and methylprednisolone respectively were 0.04, 0.06 and 2 mg kg(-1)and are in the range of the recommended doses for these drugs in mammals.

Animals↗

PubMed1999

Reduction in peripheral inflammation by changes in attention.

Peripheral inflammation in response to intra-articular injection of sodium urate was measured in birds showing pain-coping behaviour as well as in birds showing endogenous analgesia produced by changes in attention. Sixteen birds were injected with sodium urate into the left ankle joint. Eight birds were returned to their cages, and eight were placed in pairs into a novel pen. The birds placed into the novel pen showed significantly less pain coping behaviour in the 3-h period after injection than those birds returned to their cages. Both groups of birds showed elevated skin temperature over the inflamed joint, but in the birds in the novel pen this increase in temperature was significantly less than in the birds in cages. These results demonstrate that attentional shifts cannot only reduce the severe tonic pain of sodium urate arthritis, but also reduce peripheral inflammation.

Adaptation, Psychological↗

PubMed1999

Evaluation of intraarticular opioid analgesia for the relief of articular pain in the domestic fowl.

An experimental paradigm, based on the microcrystalline sodium urate-induced arthritis pain model, was used to investigate the potential peripheral analgesic properties of a variety of opioid agonists. The response criteria were changes in behavioral profiles and pain-related behaviors over 60 min commencing 1 h after intraarticular injection. The testing system was used to determine the potential optimum dose of intraarticular application of morphine sulphate (1-3 mg), fentanyl citrate (0.5-3 mg), and buprenorphine hydrochloride (0.05-1 mg). None of the opioid analgesics used had any effect on pain behavior, and it was concluded that opioids with a high affinity for the mu receptor when injected intraarticularly were unlikely to be of use in the treatment or diagnosis of inflammatory arthritic pain in the strain of domestic fowl chosen.

Analgesia↗

PubMed1998

Feeding-induced tonic pain suppression in the chicken: reversal by naloxone.

Endogenous analgesia induced by changes in motivation has been identified in the chicken in previous studies but either the motivational changes were difficult to interpret or the motivation was unpredictable. Experimental sodium urate (SU) arthritis of the ankle joint resulted in pain-coping behaviour (one-legged standing or sitting) for a 2-h period in non-food-deprived birds without access to food. Complete analgesia or marked hypoalgesia was observed in birds which had been food deprived overnight and given access to food immediately after SU injection. This analgesia seen during feeding behaviour in the food-deprived bird could be completely reversed by intravenous injection of naloxone. These results demonstrate that feeding motivation can totally suppress, in some animals, the severe tonic pain of SU arthritis and that this analgesia may be opioid mediated.

Adaptation, Psychological↗

PubMed1997

Effects of caudolateral neostriatal ablations on pain-related behaviour in the chicken.

As a measure of pain-related behaviour, beak guarding was investigated by recording the pecking response of adult chickens to a visually attractive stimulus before and after bilateral suction ablation of the caudolateral neostriatum (CLN). Two control groups of birds were used: a sham-operated group and an ablated group, in which the ablation was confined to the rostral dorsolateral telencephalon. Comparing the birds that had undergone ablation with the sham-operated controls showed that the ablation did not affect pecking behaviour. Five days after ablation, all birds were subjected to partial amputation of one third of the beak. A significant reduction in pecking behaviour (beak-guarding) was observed in both control groups, but was not observed in those birds that had previously received CLN ablations. In a second experiment, where beak amputation preceeded CLN ablation by 6 days, ablation did not affect the reduced pecking. The absence of guarding or other pain-related behaviours would indicate that an intact CLN was necessary for these behaviours to develop but, once they had developed, ablation had no effect.

Animals↗

PubMed1997

Pain-related behaviour following sodium urate arthritis is expressed in decerebrate chickens.

The role of the telencephalon in pain-related behaviour in arthritis was investigated by measuring pain-coping behaviour (one-legged standing, lameness, sitting) of birds following intra-articular injection of sodium urate crystals. Ten sham-operated and 10 decerebrate birds were injected with sodium urate into the left ankle joint 4 days after surgery, and their behaviour recorded during a 3-h period. Both groups of birds showed pain-coping behaviour, and there was no significant difference between the 2 groups of birds. These results suggest that the behaviours associated with tonic arthritic pain are organised in the brainstem.

Animals↗

PubMed1997

Sodium urate arthritis: effects on the sensory properties of articular afferents in the chicken.

The physiological properties of joint capsule mechanoreceptors in the ankle joint of the chicken were studied in the 3-h period immediately after intra-articular injection of microcrystal sodium urate. The electrical activity was recorded from single C- and A-delta sensory fibres dissected from the parafibular nerve. C-fibres showed high levels of spontaneous activity and receptive fields that varied from single spots 1 mm in diameter up to 4 x 4 mm. Thresholds to mechanical stimulation ranged from 0.1 to 8 g and 80% of the units responded to movement of the joint. A-delta fibres showed little spontaneous activity and receptive fields that varied from 1 mm to 9 x 1 mm. Thresholds to mechanical stimulation ranged from 0.1 to 16 g and 17% responded to joint movement. A comparison of the physiological properties of the C- and A-delta fibres in sodium urate arthritis with similar fibres in normal and monoarthritic animals indicated an increased sensitivity in the C-fibres but not in the A-delta fibres. Sensitisation was observed in the significantly increased receptive field size, decreased response thresholds, increased response to joint movement and the high level of spontaneous activity. These changes in the sensitivity of the joint capsule C-fibre receptors provides peripheral neural evidence for the pain experienced in acute gouty arthritis.

Animals↗

PubMed1997

Behavioural and anatomical consequences of two beak trimming methods in 1- and 10-d-old domestic chicks.

1. To examine the effects of beak trimming on behaviour, beak anatomy, weight gain, food intake and feather condition 360 ISA Brown chicks were trimmed by hot cut or cold cut at 1 d or 10 d of age or were sham-operated controls. The experiment was a 3 x 2 factorial design, with the chicks housed in littered pens in groups of 10 and observed for 6 weeks after trimming. 2. In the first week after trimming, when trimmed birds were compared with untrimmed controls, they were less active (sat and slept more), fed less, preened less and generally engaged in less beak-related behaviour. 3. These differences waned sharply during week 2 and had disappeared by week 5. There were very few differences between hot- and cold-cut birds. 4. There were also differences in production variables: trimmed birds grew more slowly during the week after trimming, their food intake was depressed for 3 weeks and food conversion efficiency improved for 2 weeks. 5. The only significant effect on feather scores was better plumage condition in the groups trimmed at 1 d and scored at 6 weeks. 6. To examine the anatomical effects 36 ISA Brown chicks trimmed by hot or cold cut at 1 d or 10 d of age were killed at 21 and 42 d after trimming, and their beaks were processed and examined histologically. In all trimmed groups healing was very rapid and no scar tissue was seen but, unlike the controls, the regrown tips contained no afferent nerves or sensory corpuscles. 7. Beak lengths immediately after trimming were 40% to 50% shorter than controls; the anatomical consequences of both methods were identical. 8. Overall, it was judged that the effects on behaviour and beak anatomy were much less severe than previously reported for birds trimmed at older ages. If birds do have to be trimmed then the procedure should be carried out in young birds: from the birds' standpoint 1 d appears to be the most suitable.

Aggression↗

PubMed1995

Endogenous analgesia in the chicken.

Endogenous analgesia has been identified in mammals, but little is known about suppression of tonic pain following trauma or disease. Birds suffer from gouty arthritis which can be induced experimentally by intra-articular injection of sodium urate (SU) crystals. SU injection into the ankle joint of the chicken tested in cages resulted in pain-coping behaviour (one-legged standing, sitting) together with severe lameness. Birds kept and tested in large pens showed significantly less pain-coping behaviour, while birds tested in novel pens showed either complete analgesia or marked hypoalgesia, together with a significant reduction in lameness. Complete analgesia was observed during pre-laying behaviour. These results demonstrate a remarkable ability of birds to suppress such severe tonic pain as SU arthritis.

Analgesia↗

PubMed1995

Projections of ankle joint afferents to the spinal cord and brainstem of the chicken (Gallus g. domesticus).

The projections of the ankle joint capsule afferents were studied by transganglionic transport of horseradish peroxidase injected directly into the ankle joint. The number and size of the labelled dorsal root ganglion cells were measured from synsacral nerves 2-9. In the dorsal root ganglia, all sizes of sensory neurones were labelled, and the largest number of labelled cells was in ganglia 5-7. The extensive sympathetic innervation of the ankle joint was identified by the large number of cell bodies labelled in the sympathetic ganglia of the paravertebral chain. Labelled afferent fibres projected to the spinal cord from the 2nd to the 8th synsacral nerves, with the rostral projection mainly via Lissauer's tract and the dorsal funiculus. Terminal labelling in the dorsal horn was identified in laminae I-III and VI, with a slight projection to V. Two areas of dense labelling, which did not correspond with the largest number of labelled dorsal root ganglion cells, were identified. A rostral area with the highest density of label was observed at the level of synsacral nerves 3-4 and a second slightly less dense area between synsacral nerves 7-8. In the caudal medulla, diffuse terminal labelling was observed in the nucleus gracilis et cuneatus, nucleus of the tractus solitarius, and the nucleus cuneatus externus. These results are discussed in a comparative context to identify similarities and differences between different primary afferent projections in birds and mammals and to highlight the possible functional significance of the avian articular afferent projection.

Afferent Pathways↗

PubMed1995

An experimental investigation of the costs and benefits of beak trimming in turkeys.

An investigation was carried out on 504 BUT 8 female poults to identify the optimum technique and age for beak trimming breeding turkeys, which have to be kept at relatively high light intensities and are thus at serious risk of cannibalism. Different groups of birds were subjected to electronic trimming (Bio-beaking) at one day old, cold cutting (with secateurs) at six days or at 21 days, or hot cutting (with a cautery iron) at six days or 21 days old. The behaviour, production traits, feather damage, injuries and mortality of the birds were measured up to 12 weeks old. None of the methods had much effect on the behaviour or production traits, other than relatively minor reductions in beak-related activities such as pecking other birds and preening, and short term depressions of food intake and bodyweight gain, and improvements in food conversion ratio. All the beak-trimming techniques resulted in marked reductions in mortality (controls 8.7 per cent, trimmed 1.6 per cent), in injuries due to cannibalism (controls 68.1/100 birds, trimmed 9.8/100 birds) and in the scores of feather damage caused by pecking (controls 1.05, trimmed 0.29). The adverse effects of beak trimming were minor and short-lived, and were clearly outweighed by the benefits in reducing cannibalism. Of the different methods, trimming with a hot blade is not recommended. Electronic trimming appeared to offer the most benefits and caused little apparent distress, but can be hazardous in unskilled hands.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

Anatomical consequences of partial beak amputation (beak trimming) in turkeys.

A detailed anatomical study was made of the effects of trimming the upper beak of turkeys. The anatomy of the normal beak was compared with that of beaks from birds which had been trimmed by one of three methods, all commonly used in the poultry industry: the Bio-Beaker which passes an electric current through the premaxilla, secateurs, or a heated blade debeaker. All three resulted in the loss of significant amounts of beak tissue. By 42 days after trimming the beak had healed with extensive regrowth, including bone and cartilage formation, and the pattern of regrowth was similar after all three methods. In the normal bird the dermis at the tip of the upper beak contains large numbers of nerve fibres and sensory receptors, but in the beak-trimmed birds the dermal tissue, although well supplied with blood vessels, was devoid of afferent nerve fibres and sensory nerve endings. In contrast with the results of previous studies with older chickens there was no evidence of neuroma formation. Trimming with secateurs was the most precise method. The heated blade damaged additional tissue close to the position of the cut, and the BioBeaker produced the most tissue damage. Behavioural studies suggested that the effectiveness of beak trimming in controlling feather pecking depends on the extent of the tissue damage.

Animals↗

PubMed1994

Sensory properties of ankle joint capsule mechanoreceptors in acute monoarthritic chickens.

The physiological properties of joint capsule mechanoreceptors in the ankle joint of monoarthritic chickens were studied by recording the electrical activity from single sensory afferent nerve fibres dissected from the parafibular nerve. A monoarticular arthritis was induced by the intra-articular injection of Freund's complete adjuvant which resulted in an acute inflammatory condition and a very rapid onset of destructive cartilage damage. A detailed description of the anatomy in both the normal and arthritic joints was presented. It was considered that by day 3 after adjuvant injection there was a reproducible severe destructive arthropathy which was of value for investigating the physiological responses of the joint capsule receptors. The majority of receptor units identified were slowly adapting mechanoreceptors which were divided into groups III (CV: 2.5-20 m/sec) and IV (CV: < 2.5 m/sec) units. At least 3 significant differences were observed in the response characteristics of the joint capsule receptors from arthritic joints compared to those receptors found in normal joints. Firstly, there was an increase in receptive field size with 62% of group IV and 80% of group III units having large receptive fields. Secondly, there was a decrease in response threshold to mechanical stimulation of the joint capsule. Thirdly, a higher proportion of units responded to joint movement in the arthritic joints. These changes in sensitivity of the joint capsule receptors showed some similarities to adjuvant arthritis models in the rat and provide peripheral neural evidence for the possible painful consequences of the inflammatory arthropathies found in chicken.

Acute Disease↗

PubMed1993

Neurogenic inflammation in the chicken (Gallus gallus var domesticus).

1. Neurogenic inflammation has been studied in the anaesthetized adult hen using a variety of different stimuli. 2. Plasma extravasation was produced following antidromic stimulation of the external mandibular ramus of the trigeminal nerve which innervates the skin at the angle of the jaw and the anterior part of the wattle. 3. Stimulation of the wattle by external application of mustard oil, thermal and mechanical stimuli, as well as intradermal injection of substance P and bradykinin, all produced plasma extravasation. 4. These results demonstrate that, in contrast to previous findings in the pigeon, at least in the trigeminal of the chicken peripheral C-fibre nociceptors have similar physiological characteristics in relation to the neurogenic inflammatory mechanism to those seen in mammals.

Anesthesia↗