The different pharmacological syndromes produced by morphine and related drugs in the chronic spinal dog led Martin and his colleagues (1,2) to suggest that these drugs exert their agonist actions 0y interacting with three distinct receptors (~,K, and e). Morphine was hypothesized to be an agonist for the p receptor, ketazocine (ketocyclazocine) was an agonist for the K receptor, and SKF-10,0q7...

The existence of neural opioid-mediated networks that are specific for the modulation of nociception is well established. Parallel non-opioid pathways exist, but their underlying physiology is little known. We now report that oxytocin administered intraperitoneally to rats, and intraperitoneally or intracisternally to mice has an anti-nociceptive effect, which is related to the activation of de...

The effects of the opiate antagonist naloxone on electrophysiological measures of human selective attention were examined utilizing a paradigm which dissociates selective information processing from any concurrent processes of general arousal that may be present. Subjects were injected with naloxone (2 mg, i.v.) or placebo prior to performing a three-channel selective listening task. The measur...

Inbred mouse lines selectively bred for divergent levels of swim induced analgesia were differed in the ability to escape electric footshock. Mice displaying a high analgesia on a hot plate, after swimming for 3 min at 20 degrees centigrade terminated electric current applied at ascending intensity to the grid floor at a higher value compared to the low analgesia line. The difference was partic...

Plasma samples were obtained before and during parturition from conscious rats implanted chronically with a jugular cannula. Rats were either allowed to remain in their nesting cage throughout parturition, or were moved immediately following the birth of the second or third pup into an empty glass chamber. The time-course of parturition was prolonged for mother rats which were moved in mid-part...

Recent studies have shown that naloxone (N), an opioid antagonist, increases concentrations of luteinizing hormone (LH) in the postpartum anestrous beef cow. However, the LH response to N was influenced by the postpartum interval. For example, a significant LH response to 200 mg of N occurred on d 42 but not on d 14 or 28 postpartum. The present study was conducted to determine the effect of di...

BACKGROUND Availability of the opioid antagonist naloxone for lay administration has grown substantially since first proposed in 1996. Gaps remain, though, in our understanding of how people who inject drugs (PWID) engage with naloxone programmes over time. AIMS This paper aimed to address three specific evidence gaps: the extent of naloxone supply to PWID; supply-source (community or prisons...

Naltrexone is a long acting opioid antagonist that is used in rehabilitation programmes to maintain heroin abstinence. It is a relatively new drug prescribed by specialists in substance misuse. Its actions and effects may not be familiar to many accident and emergency doctors or even to the people who take it. A case report is described where accidental ingestion of naltrexone results in a medi...

Human neonates and infants can become tolerant and dependent during continuous fentanyl or morphine administration. The long-term consequences in these individuals as juveniles and adults are unknown. This study compared fentanyl self-administration behavior in juvenile rats that were opioid naive or were exposed chronically to fentanyl as infants. Postnatal day 14 infant rats remained naive or...

Accumulating evidence suggests that empathy for pain recruits similar neural processes as the first-hand experience of pain. The pain-related P2, an event-related potential component, has been suggested as a reliable indicator of neural processes associated with first-hand pain. Recent evidence indicates that placebo analgesia modulates this component for both first-hand pain and empathy for pa...