The transient receptor potential vanilloid-1 (TRPV1) receptor is involved in peripheral and spinal nociceptive processing and is a therapeutic target for pain. We have shown previously that TRPV1 in the ventrolateral periaqueductal grey (VL-PAG) tonically contributes to brainstem descending antinociception by stimulating glutamate release into the rostral ventromedial medulla and OFF neuron act...

μ-Opioid receptors are among the most studied G protein-coupled receptors because of the therapeutic value of agonists, such as morphine, that are used to treat chronic pain. However, these drugs have significant side effects, such as respiratory suppression, constipation, allodynia, tolerance, and dependence, as well as abuse potential. Efforts to fine tune pain control while alleviating the s...

The opioid receptors (ORs) are known to be distributed widely in the central nervous system (CNS) and in peripheral sensory and autonomic nerves. Activation of ORs by endogenous and exogenous ligands results in a multitude of physiological functions and behaviors, e.g. pain and analgesia, stress and social status, tolerance and dependence, learning and memory, eating and drinking, and many more...

Positive social interactions are essential for emotional well-being and proper behavioral development of young individuals. Here, we studied the neural underpinnings of social reward by investigating the involvement of opioid neurotransmission in the nucleus accumbens (NAc) in social play behavior, a highly rewarding social interaction in adolescent rats. Intra-NAc infusion of morphine (0.05-0....

Morphine is the most widely used compound among narcotic analgesics and remains the gold standard when the effects of other analgetic drugs are compared. The most characteristic effect of morphine is the modulation of pain perception resulting in an increase in the threshold of noxious stimuli. Antinociception induced by morphine is mediated via opioid receptors, namely the μ-type opioid recept...

opium is one of the oldest herbal medicines currently used as an analgesic, sedative and antidiarrheal treatment. the effects of opium are principally mediated by the μ -,κ- and δ-opioid receptors. opioid substances consist of all natural and synthetic alkaloids that are derived from opium. most of their effects on gastrointestinal motility and secretion result from suppression of neural activi...

Pain is one of the most common and incapacitating symptoms experienced by patients with advanced cancer. Methadone is a potent opioid with strong affinity for the μ opioid receptor. In addition to being a potent μ opioid receptor ligand, methadone blocks the N-methyl-D-aspartic acid receptor and modulates neurotransmitters involved in descending pain modulation. These 3 properties enhance analg...

Salvinorin A is a psychoactive natural product that has been found to be a potent and selective κ opioid receptor agonist in vitro and in vivo. The activity of salvinorin A is unusual compared to other opioids such as morphine in that it mediates potent κ opioid receptor signaling yet leads to less receptor downregulation than observed with other κ agonists. Our initial chemical modifications o...