Certain personality traits, such as sociability, anxiety or depression influence the manifestations of neuropathic pain in mice, according to a new study conducted by the Neuropharmacology Laboratory (NeuroPhar) of the Pompeu Fabra University (UPF). The work, led by Rafael Maldonado, is published in the journal Neuropharmacology.

Chronic pain is a serious clinical problem with a huge economic and social burden. Currently, the treatment of chronic neuropathic pain has limited efficacy and significant adverse effects. Specifically, it appears as a consequence of a traumatic or degenerative injury of nervous structures, without an obvious stimulus. This pain is difficult to alleviate with conventional therapies and can be severe and disabling.

The high variability in the manifestations of neuropathic pain among individuals can lead to a differential response to treatments by patients, making it difficult to establish general therapeutic guidelines. The reasons for this variability are largely unknown. Therefore, identifying the factors that determine the severity of neuropathic pain manifestations is important, so the treatment can be adapted to each patient.

So, the team of researchers evaluated in rodent models how sociability, anxiety or depression affect the intensity of neuropathic pain. Miriam Martínez-Navarro, first author of the article, details: “In fact, the anxiety feature appears as a vulnerability factor that contributes to increasing pain, as well as the consequences on emotional behavior and memory. On the contrary, a sociable personality exerts a positive influence by attenuating neuropathic pain.”

The role of the amygdala

“The genetic analyzes showed that mice with high expression levels of Il6  and  Pdyn genes  in the amygdala were more sensitive to pain and these changes are also correlated with personality traits,” says Rafael Maldonado, professor of pharmacology at the UPF Department of Experimental and Health Sciences (DCEXS).

These genes code for interleukin-6 and prodynorphin, proteins involved in inflammatory and pain-sensitizing processes, which overexpression under conditions of neuropathic pain had previously been reported in other areas of the nervous system such as the spinal cord.

Interestingly, the expression of these genes in the amygdala after a nerve injury is influenced by personality traits. Thus, the anxiety trait enhances the expression of Pdyn and Il6 in the amygdala, while the trait of sociability correlates with a lower expression of Pdyn. These data suggest that the impact of personality traits on the manifestations of neuropathic pain should, in part, be due to the modulation of gene expression in the amygdala.

“The results help to understand some of the mechanisms that explain the variability of neuropathic pain manifestations depending on personality traits, which could favor the development of personalized treatments more effective for chronic pain,” concludes Rafael Maldonado.

 

Source: SINC