Epicatechin, a flavonoid, is a well-known antioxidant linked to a variety of protective effects in both humans and animals. In particular, its role in protection against cardiovascular disease has been demonstrated by epidemiologic studies. Low-dose epicatechin, which does not have significant antioxidant activity, is also protective; however, the mechanism by which low-dose epicatechin induces...

Cebranopadol (trans-69-fluoro-49,99-dihydro-N,N-dimethyl-4-phenylspiro[cyclohexane-1,19(39H)-pyrano[3,4-b]indol]-4-amine) is a novel analgesic nociceptin/orphanin FQ peptide (NOP) and opioid receptor agonist [Ki (nM)/EC50 (nM)/relative efficacy (%): human NOP receptor 0.9/13.0/89; human mu-opioid peptide (MOP) receptor 0.7/1.2/104; human kappa-opioid peptide receptor 2.6/17/67; human delta-opio...

BACKGROUND Opioid-addicted patients undergoing detoxification provide a unique opportunity to assess the effects of chronic opioid receptor stimulation on the sympathetic nervous system. We tested the hypothesis that chronic oral methadone intake decreases resting efferent sympathetic nerve activity to muscle (MSA). Furthermore, we assessed whether this effect is reversed by mu-opioid receptor ...

In the present study, the contribution of pertussis toxin (PTX)-sensitive G(i/o)-proteins to opioid tolerance and mu-opioid receptor down-regulation in the mouse were examined. Mice were injected once intracerebroventricularly and intrathecally with PTX (0.1 microg/site). Controls were treated with saline. On the 10th day following PTX treatment, continuous subcutaneous infusion of etorphine (1...

Opioid-induced constipation (OIC), a prevalent and distressing side effect of opioid therapy, does not reliably respond to treatment with conventional laxatives. OIC can be a treatment-limiting adverse event. Recent advances in medications with peripherally acting μ-opioid receptor antagonists, such as methylnaltrexone, naloxegol, and alvimopan, hold promise for treating OIC and thus extending ...

The aim of this study was to examine the effects of kappa-opioid receptor selective agonists on responses of mechanosensitive afferent fibers in the pelvic nerve. Single-fiber recordings were made from pelvic nerve afferents in the decentralized S1 dorsal root of the rat. A total of 572 afferent fibers in the S1 dorsal root were identified by electrical stimulation of the pelvic nerve; 252 (44%...

It is unclear how opioid selectivity and activation are regulated within the receptor core. In previous studies, the OFQ receptor was converted into a functional opioid receptor by mutating five amino acids at three sites to the corresponding residues conserved across the mu-, kappa-, and delta-opioid receptors, suggesting that these sites comprise an opioid binding pocket. To examine this hypo...

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....

BACKGROUND AND PURPOSE The opioid receptor family comprises four structurally homologous but functionally distinct sub-groups, the μ (MOP), δ (DOP), κ (KOP) and nociceptin (NOP) receptors. As most opioid agonists are selective but not specific, a broad spectrum of behaviours due to activation of different opioid receptors is expected. In this study, we examine whether other opioid receptor syst...