Reduced Formalin Nociceptive Responses In A Rat Model Of Post-Surgical Pain

Oyadeyi, AS; Ajao, F.O.; Afolabi, AO; Ibironke, G. F.

doi:10.4314/jbi.v3i2.30404

Cited by 3 publications

(3 citation statements)

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“…The salt-loaded rats also had reduced formalin score and increased tail-flick latency, suggesting that the salt-loaded hypertensive rats had lower pain perception frequency and higher threshold compared with the controls. The finding of higher tolerance for pain in the salt-loaded hypertensive group above that of normal diet-fed control group, though at variance with the findings of Sitsen and de Long,8 is consistent with previous studies that reported a close association between experimentally induced high blood pressure and hypoalgesia 19–22. The fact that formalin score and latency period were not significantly different in the two groups before administration of salt-loaded diet further suggested that the observed hypoalgesia after its treatment was undoubtedly induced by salt-loading hypertension.…”

Section: Discussionsupporting

confidence: 91%

“…Although both early and late phase have nociceptive effect and travel through the same pathways (ie, Aδ and C fibers), the early phase is thought to act by direct chemical stimulation of nociceptors,27 while late phase response acts through inflammation 22. The results may reflect reduced activity in chemical sensitivity of afferents, Aδ and C fibers that mediate the second phase response 21.…”

Section: Discussionmentioning

confidence: 99%

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Effects of salt-loading hypertension on nociception in rats

Afolabi¹,

Mudashiru²,

Alagbonsi³

2013

JPR

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BackgroundThere is on going controversy on the effect of experimentally induced hypertension on nociception. The effect of salt-loading-induced hypertension on pain was studied in male rats.MethodTwenty-four male Sprague-Dawley rats (160–280 g) were divided into two groups. Group A (n = 12) was treated with normal-feed diet (control), while group B (n = 12) was treated with 8% salt-loaded diet for 10 weeks. After 10 weeks of the treatment, six rats each from groups A and B were used for blood pressure measurement, while the remaining six rats were used for both the tail-flick and formalin tests. Thermal and chemical pain test were assessed using tail immersion test (tail flick) and formalin test pain paradigms at onset of salt-loading diet and after 10 weeks of salt loading.ResultsChronic administration of salt-loading diet caused significant increases (P < 0.001) in systolic blood pressure, diastolic blood pressure, and mean arterial blood pressure. Moreover, salt-loading-induced hypertension was found to significantly reduce pain sensitivity in the tail-immersion test (P < 0.001) and in the early and late phase of the formalin test (P < 0.01). However, the hypoalgesia was higher in the late phase (94.8%) than in the early phase (56.8%) of the formalin test.ConclusionThe present study suggests that high salt-loading-induced hypertension causes hypoalgesia in rats, which might be due more to reduction in inflammatory response.

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Section: Discussionsupporting

confidence: 91%

Section: Discussionmentioning

confidence: 99%

Effects of salt-loading hypertension on nociception in rats

Afolabi¹,

Mudashiru²,

Alagbonsi³

2013

JPR

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“…The formalin test, by contrast, is a prolonged, steady pain which measures the response to a long-lasting nociceptive stimulus and, therefore, resembles clinical pain. 32 The early phase is thought to act by direct chemical stimulation of nociceptors, 33 while the late phase response acts through inflammation 34 mediated by histamine, serotonin, and prostaglandins. 30 Centrally acting drugs like narcotics inhibit both phases of formalin-induced pain, while peripherally acting drugs such as aspirin only inhibit the late phase.…”

Section: Discussionmentioning

confidence: 99%

Pharmacological mechanisms involved in the analgesia induced by ethanol extract of <em>Hybanthus enneaspermus</em> leaves

Afolabi¹,

Alagbonsi²,

Aliyu³

2017

JPR

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BackgroundHybanthus enneaspermus (HE) leaves are being used traditionally to relieve pain, and scientific studies have demonstrated their analgesic potential. This study attempted to elucidate the pharmacological mechanism(s) involved in the analgesic action of ethanol extract of H. enneaspermus leaves (EEHE).Materials and methodsForty-two male Wistar rats were separately randomized into seven groups (n=6 rats in each group) for tail immersion and formalin tests. Group I (control) received distilled water (10 mL/kg) while groups II and III received acetaminophen (the reference drug, 100 mg/kg ip) and EEHE (1000 mg/kg po), respectively. Groups IV–VII were pretreated with cimetidine (50 mg/kg ip), naloxone (5 mg/kg ip), propranolol (0.15 mg/kg ip), and prazosin (0.15 mg/kg ip), respectively, 1 hour before EEHE (1000 mg/kg po) treatment.ResultsThe EEHE-induced increase in tail-flick latency was reduced by blockade of histamine and adrenergic receptors but prevented by blockade of opiate receptor in the tail-flick test. However, the EEHE-induced decrease in paw licking time was prevented only by blockade of opiate receptor but unaffected by histamine and adrenergic receptors blockers.ConclusionThese findings suggest that the analgesic effect of EEHE in different pain types may involve different neural mechanisms and that the opioidergic pathway contributes more to EEHE-induced analgesia than the other pathways.

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