Neuropeptide FF receptors exhibit direct and anti-opioid effects on mice dorsal raphe nucleus neurons

Diet-induced adaptive thermogenesis requires neuropeptide FF receptor-2 signalling

Excess caloric intake results in increased fat accumulation and an increase in energy expenditure via diet-induced adaptive thermogenesis; however, the underlying mechanisms controlling these processes are unclear. Here we identify the neuropeptide FF receptor-2 (NPFFR2) as a critical regulator of diet-induced thermogenesis and bone homoeostasis. Npffr2^−/− mice exhibit a stronger bone phenotype and when fed a HFD display exacerbated obesity associated with a failure in activating brown adipose tissue (BAT) thermogenic response to energy excess, whereas the activation of cold-induced BAT thermogenesis is unaffected. NPFFR2 signalling is required to maintain basal arcuate nucleus NPY mRNA expression. Lack of NPFFR2 signalling leads to a decrease in BAT thermogenesis under HFD conditions with significantly lower UCP-1 and PGC-1α levels in the BAT. Together, these data demonstrate that NPFFR2 signalling promotes diet-induced thermogenesis via a novel hypothalamic NPY-dependent circuitry thereby coupling energy homoeostasis with energy partitioning to adipose and bone tissue.

Excess caloric intake leads to increased thermogenesis in brown adipose tissue, to limit weight gain. Here, the authors show that neuropeptide FF receptor-2 signalling promotes thermogenesis via control of NPY expression in the arcuate nucleus, and that it absence in mice leads to a failure of activation of diet-induced thermogenesis and the development of exacerbated obesity.

Endogenous opiates and behavior: 2014

This paper is the thirty-seventh consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2014 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (endogenous opioids and receptors), and the roles of these opioid peptides and receptors in pain and analgesia (pain and analgesia); stress and social status (human studies); tolerance and dependence (opioid mediation of other analgesic responses); learning and memory (stress and social status); eating and drinking (stress-induced analgesia); alcohol and drugs of abuse (emotional responses in opioid-mediated behaviors); sexual activity and hormones, pregnancy, development and endocrinology (opioid involvement in stress response regulation); mental illness and mood (tolerance and dependence); seizures and neurologic disorders (learning and memory); electrical-related activity and neurophysiology (opiates and conditioned place preferences (CPP)); general activity and locomotion (eating and drinking); gastrointestinal, renal and hepatic functions (alcohol and drugs of abuse); cardiovascular responses (opiates and ethanol); respiration and thermoregulation (opiates and THC); and immunological responses (opiates and stimulants). This paper is the thirty-seventh consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2014 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (endogenous opioids and receptors), and the roles of these opioid peptides and receptors in pain and analgesia (pain and analgesia); stress and social status (human studies); tolerance and dependence (opioid mediation of other analgesic responses); learning and memory (stress and social status); eating and drinking (stress-induced analgesia); alcohol and drugs of abuse (emotional responses in opioid-mediated behaviors); sexual activity and hormones, pregnancy, development and endocrinology (opioid involvement in stress response regulation); mental illness and mood (tolerance and dependence); seizures and neurologic disorders (learning and memory); electrical-related activity and neurophysiology (opiates and conditioned place preferences (CPP)); general activity and locomotion (eating and drinking); gastrointestinal, renal and hepatic functions (alcohol and drugs of abuse); cardiovascular responses (opiates and ethanol); respiration and thermoregulation (opiates and THC); and immunological responses (opiates and stimulants).

Cholesterol-rich lipid rafts are involved in neuropeptide FF anti-nociceptin/orphanin FQ effect

The participation of a signaling platform to the anti-nociceptin/orphanin FQ (N/OFQ) effect of neuropeptide FF (NPFF) receptors was investigated in both acutely dissociated neurons and SH-SY5Y human neuroblastoma cells. The NPFF anti-N/OFQ, not anti-μ opioid effect, on the Ca²⁺ transient triggered by depolarization was reversed by methyl-β-cyclodextrin which depletes cholesterol from cell membranes. While the inactive α-cyclodextrin had no effect. By using [³⁵ S]GTPγS binding assay, a significant 20% decrease in the activity of nociceptin/orphanin FQ peptide receptors induced by the NPFF analog 1DMe was observed in detergent-resistant membranes, but not in total membranes of SH-SY5Y cells. Moreover, siRNA knock-down of G-protein-coupled receptor kinase 2 indicated that G-protein-coupled receptor kinase 2, but not protein kinase C, acted as the mediator in the NPFF anti-N/OFQ process. These data indicate that cholesterol-rich lipid rafts play an important role in the anti-N/OFQ effect of NPFF receptors. We proposed the participation of a signaling platform to the anti-Nociceptin/Orphanin FQ (N/OFQ) effect of Neuropeptide FF (NPFF) receptors both in mouse neurons and SH-SY5Y cells, with GRK2 protein acting as the mediator in this process. These findings should provide a more precise way to understand the anti-opioid effect of NPFF. NOP, Nociceptin/Orphanin FQ peptide.