Sex‐Related Pain Behavioral Differences following Unilateral NGF Injections in a Rat Model of Low Back Pain

Academic Article


  • Low back pain (LBP) is a globally prevalent and costly societal problem with multifacto-rial etiologies and incompletely understood pathophysiological mechanisms. To address such shortcomings regarding the role of neurotrophins in the underlying mechanisms of pain, an LBP model was developed in rats involving two unilateral intramuscular injections of nerve growth factor (NGF) into deep trunk muscles. To date, behavioral investigations of this NGF‐LBP model have been limited, especially as it pertains to female pain behaviors. This study compared mechanical sensitivity to noxious (hyperalgesia) and non‐noxious (hypersensitivity) stimuli in control and NGF‐injected male and female rats through pain resolution. Although the baseline testing revealed no differences between males and females, NGF‐injected females demonstrated prolonged ipsilat-eral deep trunk mechanical hyperalgesia that resolved seven days later than males. Moreover, females showed bilateral trunk mechanical sensitivity to noxious and non‐noxious stimuli compared to only ipsilateral behaviors in males. Sex differences were also observed in the severity of behavioral responses, with females displaying greater mean differences from baseline at several timepoints. Overall, these NGF‐LBP behavioral findings mirror some of the sex differences reported in the clinical presentation of LBP and accentuate the translatability of this NGF‐LBP model. Future studies using this LBP‐NGF model could help to elucidate the neurobiological mechanisms respon-sible for the development, severity, and/or resolution of muscular LBP as well as to provide insights into the processes governing the transition from acute to chronic LBP.
  • Authors

    Published In

  • Biology  Journal
  • Digital Object Identifier (doi)

    Author List

  • Syrett M; Reed NR; Reed WR; Richey ML; Frolov A; Little JW
  • Volume

  • 11
  • Issue

  • 6