Background & Aims
Pain is a topic of global and public health concern, as well as being directly related to the suffering of patients affected by a wide range of conditions, illnesses and injuries. Nociceptive inflammatory pain (NIP) is characterized by an inflammatory process resulting from neural damage promotes inflammatory mediators release capable of altering the stimulus response in the nociceptive terminals, increasing the sensitivity of nociceptors and consequently reducing the pain threshold, causing hyperalgesia and allodynia (Bonica et al., 1990). Nerve Growth Factor (NGF) release by neural cells in order to reverse neural damage, however, it exacerbates the threshold decrease and It intensifies hyperalgesia and pain. Classic model is the plantarNGF application. Cerebral Dopamine Neurotrophic Factor (CDNF) is a recent neurotrophic fator (CDNF). Our group resolved full-length structure (Latge et al., 2015). The aim of this study is to verify whether CDNF participates in (NIP).
Methods
Dorsal root ganglia (DRG) culture: DRG were dissected and incubated in DMEM F-12 (Gibco) containing nerve growth factor (NGF, 30 ng/mL, Life Technologies) or CDNF, Our group (1umol/L) for 72 hours at 37 °C and 5% CO2. CDNF was synthesized and purified according to (maciel et al., 2021). To investigate signaling pathways we used inhibitors of the PI3K (Wortmannin) or mTOR (Rapamycin). In vitro degeneration was caused by model NGF deprivation (Deshmukh and Johnson, 1997).
A specific marker for neurites, TUJ-1 antibody was used.
Neuritic extension, neuritogenesis area and collaterals were calculated.
Cell viability was measured by LDH assay.
In vivo assay
Animal test: Animals were divided into groups according to treatment: Vehicle (PBS), NGF and CDNF. 9 animals per group.
The animals were subjected to a plantar application on the right hind paw. Afterwards, von Frey hair test was applied before treatment (baseline), 1, 3, 6, 9 and 24 h after injection to verify pain.
Results
In DGR cultures it was possible to observe that CDNF is able to stimulating neuritogenic potential and neuroprotection in peripheral neurons. CDNF promoted viability of these cells, neurite growth and collateral sprout formation, in addition to protecting against axonal degeneration in vitro. Interestingly, our results data demonstrate in a pioneering way that CDNF has effect on sensory neurons. Futhermore, NGF and CDNF share signaling pathways (PI3K and mTOR).
In a nociceptive pain model, it was observed by the von fry hair test that CDNF was able to reduce the animals’ sensitivity at the first timepoint and this effect persists for up to 6-9 hours compared to the vehicle group. The effect of CDNF was similar to that of NGF, a classic factor in this model.
Conclusions
In a pioneering way, this study shows that CDNF has effects on sensory neurons. In summary, CDNF stimulates neuritic potential, in addition to promoting neuroprotection in an in vitro degeneration model.
Our initial in vivo findings indicate for the first time that CDNF is related to nociceptive inflammatory pain. Surprisingly, CDNF was able to lower the threshold of nociceptive neurons, promoting hypersensitivity and pain. These data suggest that CDNF participates in DNI, making it an alternative factor for this model and, more importantly, a possible new target for the search for analgesic agents.
We are now evaluating CDNF residues and mutants in order to identify the sequence that produces the effect and, thus, look for inhibitors with analgesic effects.
References
Bonica JJ, Yaksh T, Liebeskind JC et al – Biochemistryand modulation of nociception and pain.
The Management of Pain, 2nd Ed, vol1, Malvern, Lea & Febiger,1990; 95-121.
Cristiane Latge , Katia M S Cabral , Guilherme A P de Oliveira , Diana P Raymundo , Julia A Freitas , Laizes Johanson , Luciana F Romão , Fernando L Palhano , Torsten Herrmann , Marcius S Almeida , Debora Foguel. The Solution Structure and Dynamics of Full-length Human Cerebral Dopamine Neurotrophic Factor and Its Neuroprotective Role against ?-Synuclein Oligomers. J Biol Chem
. 2015 Aug 14;290(33):20527-40. doi: 10.1074/jbc.M115.662254. Epub 2015 Jul 6.
Leonardo Maciel , Dahienne Ferreira de Oliveira , Fernanda Mesquita , Hercules Antônio da Silva Souza , Leandro Oliveira , Michelle Lopes Araújo Christie , Fernando L Palhano , Antônio Carlos Campos de Carvalho , José Hamilton Matheus Nascimento , Debora Foguel. New Cardiomyokine Reduces Myocardial Ischemia/Reperfusion Injury by PI3K-AKT Pathway Via a Putative KDEL-Receptor Binding. J Am Heart Assoc . 2021 Jan 5;10(1):e019685. doi: 10.1161/JAHA.120.019685. Epub 2020 Dec 29.
M Deshmukh , E M Johnson Jr. Programmed cell death in neurons: focus on the pathway of nerve growth factor deprivation-induced death of sympathetic neurons. Mol Pharmacol
. 1997 Jun;51(6):897-906. doi: 10.1124/mol.51.6.897.
Presenting Author
Raphael Santos
Poster Authors
Raphael Santos
PhD
federal University of Rio de Janeiro
Lead Author
Alexandre Nascimento. Graduate student
University of São Paulo (USP)
Lead Author
Ana Maria Rodrigues. Postdoctoral student
University of São Paulo (USP)
Lead Author
Camila Squarzoni Dale
Department of Anatomy, Institute of Biomedical Sciences, University of Sao Paulo
Lead Author
Deborah Schechtman
PhD.
Institute of Chemistry of University of São Paulo - Brazil
Lead Author
Debora Foguel
Federal University of Rio de Janeiro (UFRJ)
Lead Author
Topics
- Specific Pain Conditions/Pain in Specific Populations: Acute Pain and Nociceptive Pain