The Effects of Pre-emptive Administration of Ketamine and norBNI on Pain Behavior, c-Fos, and Prodynorphin Protein Expression in the Rat Spinal Cord after Formalin-induced Pain Is Modulated by the DREAM Protein

Abstract

BackgroundWe investigated the effects of pre-emptive administration of ketamine and norBNI on pain behavior and the expression of DREAM, c-Fos, and prodynorphin proteins on the ipsilateral side of the rat spinal cord at 2 and 4 hours after formalin injection.MethodsEighty-four male Sprague Dawley rats were divided into 4 major groups consisting of control rats (C) (n = 12), rats given only formalin injections (F) (n = 24), and rats treated with pre-emptive administration of either ketamine (K+F) (n = 24) or norBNI (N+F) (n = 24). The non-control groups were further divided into subgroups consisting of rats that were sacrificed at 2 and 4 hours (n = 12 for each group) after formalin injection. Pain behavior was recorded for 1 hour. After 2 and 4 hours, the rats were sacrificed and the spinal cords (L4-L5 sections) were removed for immunohistochemistry and Western blot analysis.ResultsThe pain behavior response was reduced in the K+F group compared to the other groups during the second phase of the formalin pain response. We detected an increase in the nuclear DREAM protein level in the K+F group at 2 and 4 hours and a transient decrease in the N+F group at 2 hours; however, it increased at 4 hours after injection. Fos-like immunoreactivity (FLI) and Prodynorphin-like immunoreactivity (PLI) neurons decreased in the K+F group but increased in the N+F group at 2 hours after injection. While FLI decreased, PLI increased in all groups at 4 hours after injection.ConclusionsWe suggest that NMDA and kappa opioid receptors can modulate DREAM protein expression, which can affect pain behavior and protein transcriptional processes at 2 hours and bring about either harmful or protective effects at 4 hours after formalin injection.

Minocycline attenuates the development of diabetic neuropathy by modulating DREAM and BDNF protein expression in rat spinal cord

“…It is the reason for sacrificing the rats at three days after formalin injection. Thoracotomy and perfusion fixation technique was performed to expose rats spinal cord according to our previous study [27]. The lumbar enlargement of L4-L5 spinal cord segment were sectioned (40 μm thickness) using a cryostat and sections were rinsed with Tris-buffered saline (TBS) twice for 5 min each and incubated overnight at 4°C with primary mouse monoclonal antibody for OX-42 protein (microglia protein marker) diluted to 1:500 in buffer (mixture of TBS with 2% normal goat or horse serum and 0.2% Triton-X) followed by incubation with biotinylated horse anti-mouse IgG (for microglia protein) diluted at 1:200 in buffer (mixture of TBS with 2% normal goat/horse serum and 0.2% Triton-X) for 1 h with gentle agitation at room temperature.…”

Emerging Role of DREAM in Healthy Brain and Neurological Diseases

“…For these reasons, the pharmacological inhibition of DREAM may represent an interesting new analgesic strategy for the treatment of pain because of the lack of typical side-effects of opioids. Moreover, formalin injections cause an increase in DREAM protein expression in the spinal cord of rat models of inflammatory pain [69], showing a possible feedback regulation of DREAM expression by inflammatory pain. In addition, more recently, it was found that the N-terminal 31-50 fragment of DREAM interacts with transient receptor potential vanilloid 1 (TRPV1) and reduces its surface localization in the rat dorsal root ganglia.…”

Minocycline alleviates nociceptive response through modulating the expression of NR2B subunit of NMDA receptor in spinal cord of rat model of painful diabetic neuropathy

“…Meanwhile, the duration of time (seconds) the rat spent licking the injected paw was recorded for up to 60 min. The data was then summed for phase 1 (acute pain and peripheral actions: 0 to 10 min post-formalin injection), early phase 2 (early chronic pain and central actions: 15 to 35 min), and late phase 2 (late chronic pain and central actions: 40 to 60 min) [25].…”