Effects of the dual FAAH/MAGL inhibitor AKU-005 on trigeminal hyperalgesia

This dataset comprises the findings obtained in the study aimed at investigating the effects of AKU-005, a dual fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL) inhibitor, in an in vivo model of migraine based on nitroglycerin (NTG) administration. AKU-005 (0,5 mg/Kg, i.p.) or its vehicle (10% polyethylene glycol 200, 10% tween 80 and saline) was administered 3 h after NTG (10mg/kg i.p.) or its vehicle (6% alcohol and 16% propylene glycol and saline) and after 1 h rats were sacrificed or tested for behavioral assessments depending on the experimental set.

In vivo assessments:

- Open field test: distance (expressed in meters) travelled in the apparatus, time spent (expressed in seconds) in the center of the apparatus, number of rearing, time spent in grooming behavior (expressed in seconds) were evaluated. Each animal was placed in a 92 x 92 cm arena and videorecorded for 10 minutes. The analysis was done manually (for rearing and grooming) and with the ANY-Maze software (for total distance and time in the center).

-Pain-related behavior in the 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.

Ex vivo assessments:

- Gene expression analysis: mRNA expression levels of calcitonin gene-related peptide (CGRP), tumor necrosis factor alpha (TNF-alpha), interleukin-6 (IL-6) in the meninges, medulla, cervical spinal cord, trigeminal ganglion ipsilateral to 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.

- CGRP protein levels in serum: the blood samples were collected in clot activator with gel separator serum tubes and centrifugated for 15 min at 1500×g. Serum CGRP levels were measured using a commercial enzyme-linked immuno-sorbent assay (ELISA) kit (Elabsciences). Data are expressed as pg/ml.

- Lipid levels: measurement of endocannabinoids (N-arachidonoylethanolamine and 2-arachidonoylglycerol) and related lipids (palmitoylethanolamide and oleoyl ethanolamide) by HPLC in medulla, cervical spinal cord and trigeminal ganglion (expressed as ng/g tissue).

RESULTS:

AKU-005 reduces NTG-induced hyperalgesia during the orofacial formalin test but did not influence NTG-induced changes in the open field test. Furthermore, AKU-005 significantly reduced the gene expression of CGRP, TNF-alpha, and IL-6 in the meninges, trigeminal ganglia, cervical spinal cord, medulla, and CGRP serum levels. Surprisingly, AKU-005 caused no change in cranial levels of endocannabinoids and related lipids.