A behavioral hypalgesia (increased response threshold to noxious stimuli) has been
consistently, although not invariably, reported in spontaneous and experimental acute and …

Chronic pain differs from acute pain in that it serves no useful function, causes suffering,
limits activities of daily living, and increases costs of healthcare payments, disability, and …

Of the three major types of opioid receptors (μ, δ κ) in the nervous system, μ‐opioid receptor
shows the highest affinity for morphine that exerts powerful effects on nociceptive …

The present study was conducted to demonstrate immunohistochemically, the sites of c-fos
protein expression in the brains of mice subjected to acute and chronic social defeat stress …

Opioid-produced antinociception in mammals seems to be mediated in part by pathways
originating in the periaqueductal gray (PAG) and the rostroventral medulla (RVM), and these …

Background Opioids produce analgesia by direct effects as well as by activating neural
pathways that release nonopioid transmitters. This study tested whether systematically …

The noradrenergic system is considered to be one of the major descending analgesia
systems originating in the brainstem. The relationship between the periaqueductal gray …

The 1965 hypothesis proposed the following: 1. excitatory impulses originating from both
noxious and innocuous stimuli converged onto common cells in the dorsal horn; 2. impulses …

In previous studies, we reported that supraspinally administered DAMGO, a mu-opioid
agonist, produces a dose-related, naloxone-reversible inhibition of formalin-evoked pain …

Recent studies suggest that non-steroidal anti-inflammatory drugs have central sites of
action which contribute to their analgesic efficacy. In the present study microinjections of the …