introduction: transient receptor potential vanilloid type 1 (trpv1) and protein kinase cγ (pkcγ) are involved in sensitization/desensitization to noxious stimuli. we aimed to examine the gene expression levels of trpv1 and pkcγ in rat lumbosacral cord and midbrain on days 1, 4 and 8 of induction of morphine analgesic tolerance. methods: two groups of male wistar rats received twice daily saline...

BACKGROUND Clinical studies indicate that patients with post-traumatic stress disorder (PTSD) frequently share comorbidity with numerous chronic pain conditions. However, the sustained effects of PTSD-like stress over time on visceral nociception and hyperalgesia have been rarely studied, and the underlying mechanisms of stress-induced modulation of visceral hyperalgesia remain elusive. The pur...

BACKGROUND Excitatory interneurons account for the majority of neurons in laminae I-III, but their functions are poorly understood. Several neurochemical markers are largely restricted to excitatory interneuron populations, but we have limited knowledge about the size of these populations or their overlap. The present study was designed to investigate this issue by quantifying the neuronal popu...

The previous study indicated that aquaporin 4 (AQP4) deficiency attenuated opioid physical dependence. However, the underlying mechanism remains unknown. In the present study, the effects of AQP4 deficiency on the expression of three factors, protein kinase C (PKC) α, PKCγ and c-Fos in the spinal cord, which are known to be concerned with spinal neuronal sensitization and opiate dependence, wer...

Cerebellar motor coordination and cerebellar Purkinje cell synaptic function require metabotropic glutamate receptor 1 (mGluR1, Grm1). We used an unbiased proteomic approach to identify protein partners for mGluR1 in cerebellum and discovered glutamate receptor δ2 (GluRδ2, Grid2, GluΔ2) and protein kinase Cγ (PKCγ) as major interactors. We also found canonical transient receptor potential 3 (TR...

BACKGROUND Morphine-induced hyperalgesia and tolerance significantly limits its clinical use in relieving acute and chronic pain. Melatonin, a pineal gland neurohormone, has been shown to participate in certain neuropsychopharmacological actions. The present study investigated the effect of melatonin on morphine-induced hyperalgesia and tolerance and possible involvement of protein kinase C (PK...

Recent studies indicate a critical role for metabotropic glutamate receptor 5 (mGluR5) in the reinstatement of cocaine seeking. However, the signal transduction pathways through which mGluR5s regulate cocaine seeking have not been identified. Here, we show that intra-accumbens shell administration of an mGluR5 (9.0 μm MPEP), but not mGluR1 (50.0 μm YM 298198), antagonist before a priming inject...

AIMS Morphine signaling via the μ-opioid receptor (MOR) is coupled to redox-dependent zinc release from endogenous stores. Thus, MOR activation stimulates the complex formed by RGSZ2 (a regulator of G protein signaling) and neural nitric oxide synthase (nNOS) to produce NO, and to recruit PKCγ and Raf-1 in a zinc-dependent manner. Accordingly, we investigated whether redox regulation of zinc me...

AIMS The in vivo pharmacology of the sigma 1 receptor (σ1R) is certainly complex; however, σ1R antagonists are of therapeutic interest, because they enhance mu-opioid receptor (MOR)-mediated antinociception and reduce neuropathic pain. Thus, we investigated whether the σ1R is involved in the negative control that glutamate N-methyl-d-aspartate acid receptors (NMDARs) exert on opioid antinocicep...