Effects of Botulinum toxin type A on nitroglycerin-induced trigeminal hyperalgesia

This dataset comprises the findings obtained in the study aimed at investigating the the anti-hyperalgesic effect of Botulinum toxin type A (BoNT/A) in an animal model of migraine based on nitroglycerin (NTG) administration to provide a deeper understanding of how it modulates pain pathways. Male rats were treated unilaterally with BoNT/A (25 μl bolus of 10 U/kg) or 0.9% saline (25 μL) into the right upper lip seven days before NTG (10 mg/kg, i.p.) and NTG vehicle administration. Four hours after NTG/NTG vehicle administration rats were subjected to the orofacial formalin test, at the end of which the medulla-pons area and the trigeminal ganglia were collected and processed for RT-PCR analysis. - Orofacial formalin test: the face rubbing was measured counting the seconds the animal spent grooming the injected area (upper lip, lateral to the nose) with the ipsilateral forepaw or hindpaw 0–3 min (Phase I) or 12–45 min (Phase II) after formalin injection (50 µl, s.c.). The observation time was divided into 15 blocks of 3 min each. - Gene expression analysis: mRNA expression levels of calcitonin gene-related peptide (CGRP), pituitary adenylate cyclase-activating polypeptide (PACAP), vasoactive intestinal peptide (VIP) in the medulla-pons and trigeminal ganglion ipsilateral and contralateral to BoNT/A and formalin injection. mRNA levels were measured by rt-PCR. All samples were assayed in triplicate and gene expression levels were calculated according to the ΔΔCt method and expressed as relative quantification. RESULTS: BoNT/A reduces NTG-induced hyperalgesia during the orofacial formalin test. Additionally, it significantly reduced the gene expression of CGRP, PACAP, and VIP in the medulla-pons compared to NTG. Pre-treatment with BoNT/A in NTG-challenged rats prevented the increase in mRNA levels of CGRP and VIP in both trigeminal ganglia, while PACAP was only reduced in the ipsilateral trigeminal ganglion.