The formalin test: an evaluation of the method.

The formalin test for nociception, which is predominantly used with rats and mice, involves moderate, continuous pain generated by injured tissue. In this way it differs from most traditional tests of nociception which rely upon brief stimuli of threshold intensity. In this article we describe the main features of the formalin test, including the characteristics of the stimulus and how changes in nociceptive behaviour may be measured and interpreted. The response to formalin shows an early and a late phase. The early phase seems to be caused predominantly by C-fibre activation due to the peripheral stimulus, while the late phase appears to be dependent on the combination of an inflammatory reaction in the peripheral tissue and functional changes in the dorsal horn of the spinal cord. These functional changes seem to be initiated by the C-fibre barrage during the early phase. In mice, the behavioural response in the late phase depends on the ambient temperature. We argue that the peripheral tissue temperature as well as other factors influencing the peripheral inflammation may affect the response, possibly confounding the results obtained with the test. Furthermore, we discuss the methods of recording the response and the value of observing more than one aspect of behaviour. Scoring of several behavioural variables provides a means of assessing motor or sensorimotor function as possible causes for changes in behaviour. In conclusion, the formalin test is a valuable addition to the battery of methods available to study nociception.

Spatial and temporal aspects of spinal cord and brainstem activation in the formalin pain model

Measurement of pain and analgesia in animals poses a variety of problems. In addition to the fact that pain itself constitutes a multiplicity of sensory entities, the term pain is poorly defined in relationship to animals and animal behaviour.

Animal Models of Analgesia

Objective—To determine anesthetic techniques and the drugs used to provide anesthesia and analgesia to reptiles. Design—Mail-out questionnaire. Sample Population—367 members of the Association of Reptile and Amphibian Veterinarians. Procedure—1,091 members listed in the 2002 directory of the Association of Reptile and Amphibian Veterinarians were asked to complete a questionnaire regarding anesthesia and analgesia. Results—367 of 1,091 (33.6%) individuals completed the questionnaire; 88.8% used inhalants (particularly isoflurane) for anesthesia, and ketamine, propofol, and butorphanol were the most commonly used injectable agents. Intubation, fluids, and having a dedicated anesthetist were most commonly used for patient support, and pulse oximetry and Doppler ultrasonography were most commonly used for monitoring. Respiratory depression, difficulty monitoring anesthetic depth, prolonged recovery, and hypothermia were the most frequent complications. Nearly all respondents believed that reptiles feel pain,...

Evaluation of the use of anesthesia and analgesia in reptiles

Analyse de l'existence et de la sensibilite d'un systeme nociceptif chez C.n. africana par l'utilisation de 3 tests experimentaux

Nociception in Crocodiles: Capsaicin Instillation, Formalin and Hot Plate Tests: COMMUNICATION: Physiology

Comparative investigations were made between wild and domestic ruminants from arid and semi-arid regions and those species from non-arid areas in an attempt to evaluate the adaptations of these ruminants in terms of the effects of heat stress and dehydration on food intake and digestibility. The effect of (a) an intermittent heat load (a daily light cycle of 12 h at 22 degrees C and 12 h at 40 degrees C) compared to 22 degrees C throughout the day and (b) dehydration level of 15% weight loss, with and without the heat load, on the intake and digestibility of a poor quality hay was investigated in the Grant's gazelle, Oryx, the domestic Turkana goats, fat-tailed sheep, zebu cattle, Thomson's gazelle and wildebeest. The intermittent heat load with water available ad libitum depressed the food intake of zebu cattle and Turkana goats by more than 40%. It had no significant effect on the food intake of the other species. The Thomson's and Grants gazelle, oryx, wildebeest and fat-tailed sheep appear well adapted to withstanding a periodic heat load. Dehydration at 22 degrees C caused a marked depression on food intake of all the species investigated. Dehydration together with a heat load caused no further reduction in the food intake by the Grants's gazelle, oryx, and goats but it did cause a further reduction in the intake in the other species. The small non-domestic ruminants (i.e. Grant's and Thomson's gazelle) appear much more digestive efficient than any of their domestic counterpart.

Effects of dehydration and heat stress on food intake and dry matter digestibility in East African ruminants

Data available on the role of the opioid systems of the naked mole-rat in nociception is scanty and unique compared to that of other rodents. In the current study, the effect of DAMGO, DPDPE and U-50488 and U-69593 on formalin-induced (20 microl, 10%) nociception were investigated. Nociceptive-like behaviors were quantified by scoring in blocks of 5 min the total amount of time (s) the animal spent scratching/biting the injected paw in the early (0-5 min) and in the late (25-60 min) phase of the test. In both the early and late phases, administration of 1 or 5 mg/kg of DAMGO or DPDPE caused a naloxone-attenuated decrease in the mean scratching/biting time. U-50488 and U-69593 at all the doses tested did not significantly change the mean scratching/biting time in the early phase. However, in the late phase U-50488 or U-69593 at the highest doses tested (1 or 5 mg/kg or 0.025 or 0.05 mg/kg, respectively) caused a statistically significant and naloxone-attenuated decrease in the mean scratching/biting time. The data showed that mu, delta or kappa-selective opioids causes antinociception in the formalin test in this rodent, adding novel information on the role of opioid systems of the animal on pain regulation.

Activation of micro, delta or kappa opioid receptors by DAMGO, DPDPE, U-50488 or U-69593 respectively causes antinociception in the formalin test in the naked mole-rat (Heterocephalus glaber).

Five locally known plants, Solanum aculeastrum, Erythrina abyssinica, Carissa edulis, Croton megalocarpus and Myrica salicifolia used by Maasai traditional healers for treatment of bacterial infections were extracted using chloroform, ethanol and water. The extracts obtained were then tested for in-vitro antibacterial activity on clinical isolates of gram-positive bacteria; Staphylococcus aureus and gram-negative bacteria; Escherichia coli, Pseudomonas aerugenosa, Salmonella typhi and Krebsiella pneumonaie. The activity of the water extracts of all the plants was the highest, followed by ethanol and chloroform extracts respectively. The water extract of Croton megalocarpus was observed to be the most active against all strains of bacteria.

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Antibacterial activity of five medicinal plant extracts used by the maasai people of kenya

The effects of intragastric arterial infusions (1 mL min−1) of physiological saline, vasoactive intestinal polypeptide (VIP) or VIP-antagonist [4Cl-D-Phe6, Leu17] VIP (1 nmol mL−1) on electromyographic (EMG) activities of the reticulum and reticulo-omasal orifice (ROO) in conscious, solid, meal-fed ewes kept in either warm (18 °C) or cold (1 °C) environments were studied. Infusions were of 15 min duration before, during and after feeding in both environments. In each ruminoreticular cycle the ROO showed long bursts of EMG activity coincidental with reticular EMG activity. Quiescence of the ROO was never fully observed until the reticulum relaxed. The frequencies of reticular bursts in both environments were higher during the period of active eating than during the post- and prefeeding periods. Infusion of VIP in the warm but not in the cold environment reduced frequency of reticular EMG. Compared with saline and antagonist, VIP increased the mean duration of the ROO quiescence to 13 s in the cold environm...

J. O. Miaron

Papers

Nociception in Crocodiles: Capsaicin Instillation, Formalin and Hot Plate Tests: COMMUNICATION: Physiology

Effects of dehydration and heat stress on food intake and dry matter digestibility in East African ruminants

Activation of micro, delta or kappa opioid receptors by DAMGO, DPDPE, U-50488 or U-69593 respectively causes antinociception in the formalin test in the naked mole-rat (Heterocephalus glaber).

Antibacterial activity of five medicinal plant extracts used by the maasai people of kenya

Vasoactive intestinal polypeptide inhibits electromyographic activity of the reticulo-omasal orifice in meal-fed sheep in warm and cold environments