Forebrain medial septum region facilitates nociception in a rat formalin model of inflammatory pain
| Autor: | Mohammed Zacky Ariffin, Sanjay Khanna, Shabbir Moochhala, Jenn Zhou Ye, Andy Thiam-Huat Lee, Mingyi Zhou |
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| Rok vydání: | 2011 |
| Předmět: |
Agonist
Male Nociception Zolpidem medicine.medical_specialty medicine.drug_class Hippocampus Pain Hippocampal formation Rats Sprague-Dawley chemistry.chemical_compound Neuritis Internal medicine medicine Animals Pain Measurement business.industry Nociceptors Rats Disease Models Animal Anesthesiology and Pain Medicine Endocrinology Neurology Muscimol chemistry Forebrain Septum of Brain Neurology (clinical) business Licking Neuroscience medicine.drug |
| Zdroj: | PainReferences. 152(11) |
| ISSN: | 1872-6623 |
| Popis: | The medial septum is anatomically and functionally linked to the hippocampus, a region implicated in nociception. However, the role of medial septum in nociception remains unclear. To investigate the role of the region in nociception in rats, muscimol, a GABA agonist, or zolpidem, a positive allosteric modulator of GABA(A) receptors, was microinjected into medial septum to attenuate the activity of neurons in the region. Electrophysiological studies in anesthetized rats indicated that muscimol evoked a stronger and longer-lasting suppression of medial septal-mediated activation of hippocampal theta field activity than zolpidem. Similarly, microinjection of muscimol (1 or 2 μg/0.5 μl) into the medial septum of awake rats suppressed both licking and flinching behaviors in the formalin test of inflammatory pain, whereas only the latter behavior was affected by zolpidem (8 or 12 μg/0.5 μl) administered into the medial septum. Interestingly, both drugs selectively attenuated nociceptive behaviors in the second phase of the formalin test that are partly driven by central plasticity. Indeed, muscimol reduced the second phase behaviors by 30% to 60%, which was comparable to the reduction seen with systemic administration of a moderate dose of the analgesic morphine. The reduction was accompanied by a decrease in formalin-induced expression of spinal c-Fos protein that serves as an index of spinal nociceptive processing. The drug effects on nociceptive behaviors were without overt sedation and were distinct from the effects observed after septal lateral microinjections. Taken together, these findings suggest that the activation of medial septum is pro-nociceptive and facilitates aspects of central neural processing underlying nociception. |
| Databáze: | OpenAIRE |
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