Regulation of spinal Cav2.2 is involved in pain transmission of herpetic neuralgia 

Heloísa Alonso Matieloa, Erika Paula Machado Peixotob, Adilson Silva Alvesc, Luiz Roberto Giorgetti de Brittoc, Cláudio Romero Farias Marinhob, Gerald Zamponid, Thiago Mattar Cunhae, Camila Squarzoni Dalea. 

aDepartment of Anatomy, ICB/USP– São Paulo, SP- email: heloisa.matielo@usp.br;  camila.dale@usp.br

bDepartment of Parasitology, ICB/USP - São Paulo, SP- emails: e.machado@usp.br; marinho@usp.br 

cDepartment of Physiology, ICB/USP - São Paulo, SP- emails: adilsonusp@gmail.com; britto@icb.usp.br 

d Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada- email: zamponi@ucalgary.ca

eFaculty of Medicine of Ribeirão Preto – USP – São Paulo, SP- email: thicunha@fmrp.usp.br

 

Background and Aims: Herpetic (HN) and post-herpetic neuralgia (PHN) constitute the herpes zoster pain phases. Cav2.2 is a N-type high voltage-gated calcium channel involved in pain transmission in peripheral and central pathways, also being a target of drugs used for chronic pain treatment. Herein, we aimed to assess the development of hypersensitivity in HN and PHN mice and the involvement of Cav2.2 in HN painful transmission by the administration of Pregabalin and Ziconotide and evaluation of Cav2.2 levels in the spinal cord. Methods: C57BL/6 male mice (8 weeks, 25g-30g, Ethical Committee nº2319150920) were inoculated with Herpes simplex virus (HSV-1 2x107; 50 µl) as described by Silva et al. (J. of Neurosc. 37: 6408, 2017), and were evaluated for mechanical, heat and cold hypersensitivity by von Frey filaments, hot plate and acetone tests, respectively at 9 days post induction (dpi). General behavior was evaluated by rota rod test. Pregabalin (100mg/kg; 100ul i.p.) or Ziconotide (10pmol; 20ul i.t.) were injected and animals evaluated after 30 or 10 min, respectively. Fresh and fixed with 4% paraformaldehyde spinal cord samples were collected after 9dpi and 30min after pregabalin treatment. Cav2.2 was analyzed by western blotting and immunohistochemistry.  Data was analyzed using GraphPad Prism by One- way or two-way ANOVA followed by Bonferroni post-hoc test. p<0.05 was considered significant. Results: Animals showed ipsilateral mechanical hypersensitivity and heat hyposensitivity, without changes in cold sensitivity. Pregabalin but not ziconotide induced antinociception. No changes on locomotion where observed. Cav2.2 levels assessed by western blotting was increased in HN compared to Sham. Imunoreactivity for Cav2.2 in ipsilateral dorsal and ventral spinal cord were similar in HN and Sham, but decreased in PGB-treated HN mice.  Conclusions: Our results demonstrate the regulation of Cav2.2 as a potential target in painful pathways involved with Herpetic Neuralgia. 

References: Financial support: FAPESP-202012120-4. Relevance for Patient Care: We present the Cav2.2 as a valuable target for the orientated treatment of patients with Herpetic and Post-Herpetic Neuralgia.