neuropeptide-y and adenosine-3--5--cyclic-phosphorothioate

The nucleus accumbens (NAc) brain structures have been implicated in the reward and reinforcing properties of ethanol. The present study investigated the role of nucleus accumbal cyclic AMP (cAMP)-dependent protein kinase A (PKA) signaling in alcohol drinking and anxiety-like behaviors of rats. It was found that infusion of PKA inhibitor (Rp-cAMP) into the NAc shell significantly increased the alcohol but not the sucrose intake, without modulating the anxiety-like behaviors, as measured by elevated plus maze test in rats. PKA inhibitor infusion into the NAc shell significantly decreased the protein levels of alpha-catalytic subunit of PKA (PKA-Calpha) and phosphorylated cAMP response element-binding protein (p-CREB) as well as decreased the protein levels of neuropeptide Y (NPY) in the shell but not in the NAc core of rats. On the other hand, infusion of PKA activator (Sp-cAMP) or NPY alone into the NAc shell did not produce any changes in alcohol intake; however, when these agents were coinfused with PKA inhibitor, they significantly attenuated the increases in alcohol preference induced by pharmacological inhibition of PKA. Interestingly, PKA activator coinfusion with PKA inhibitor into the NAc shell significantly normalized the PKA inhibitor-induced decreases in the protein levels of PKA-Calpha and p-CREB as well as of NPY in the NAc shell of rats. Taken together, these results provide the first evidence that decreased PKA function in the NAc shell is involved in alcohol drinking but not in anxiety-like behaviors of rats. Furthermore, decreased function of PKA may regulate alcohol drinking behaviors via CREB-mediated decreased expression of NPY in the NAc shell of rats.

Topics: Alcohol Drinking; Animals; Anxiety; Behavior, Animal; Central Nervous System Depressants; Cyclic AMP; Cyclic AMP Response Element-Binding Protein; Cyclic AMP-Dependent Protein Kinases; Dose-Response Relationship, Drug; Drinking; Drug Interactions; Ethanol; Immunohistochemistry; Male; Maze Learning; Neuropeptide Y; Nucleus Accumbens; Protein Kinase Inhibitors; Rats; Rats, Sprague-Dawley; Thionucleotides; Time Factors

We investigated the role of cAMP-responsive element-binding protein (CREB) in genetic predisposition to anxiety and alcohol-drinking behaviors using alcohol-preferring (P) and -nonpreferring (NP) rats. The levels of CREB, phosphorylated CREB, and neuropeptide Y (NPY) were innately lower in the central amygdala (CeA) and medial amygdala (MeA), but not in the basolateral amygdala (BLA), of P rats compared with NP rats. P rats displayed higher baseline anxiety-like behaviors and consumed higher amounts of alcohol compared with NP rats. Ethanol injection or voluntary intake reduced the higher anxiety levels in P rats. Ethanol also increased CREB function in the CeA and MeA, but not in the BLA, of P rats. Infusion of the PKA activator Sp-cAMP or NPY into the CeA decreased the alcohol intake and anxiety-like behaviors of P rats. PKA activator infusion also increased CREB function in the CeA of P rats. On the other hand, ethanol injection or voluntary intake did not produce any changes either in anxiety levels or on CREB function in the amygdaloid structures of NP rats. Interestingly, infusion of the PKA inhibitor Rp-cAMP into the CeA provoked anxiety-like behaviors and increased alcohol intake in NP rats. PKA inhibitor decreased CREB function in the CeA of NP rats. These novel results provide the first evidence to our knowledge that decreased CREB function in the CeA may be operative in maintaining the high anxiety and excessive alcohol-drinking behaviors of P rats.

Topics: Alcoholism; Amygdala; Animals; Anxiety; Behavior, Animal; Cyclic AMP; Cyclic AMP Response Element-Binding Protein; Cyclic AMP-Dependent Protein Kinases; Genetic Predisposition to Disease; Humans; Male; Neuropeptide Y; Protein Kinase Inhibitors; Rats; Rats, Inbred Strains; Signal Transduction; Thionucleotides

Following central administration, neuropeptides that decrease the level of cAMP induce feeding. Conversely, cAMP activating neuropeptides tend to elicit satiety. When the inhibitory effect of neuropeptide Y (NPY) on the hypothalamic cAMP production was blocked by pertussis toxin, the potent orexigenic effect of NPY was lost. These findings suggest that there may be a link between hypothalamic cAMP and the central regulation of food intake. In this report, we show that the injection of the membrane-permeable cAMP agonist, adenosine-3',5'-cyclic monophosphorothioate Sp-isomer (Sp-cAMP), into perifornical hypothalamus (PFH) significantly inhibited schedule-induced and NPY-induced food intake for up to 4h. This inhibitory effect was normalized within 24h. A taste aversion could not be conditioned to Sp-cAMP treatment, suggesting that the anorectic response was not due to malaise. Sp-cAMP administration significantly increased the active protein kinase A (PKA) activity in dorsomedial (DMH) and ventromedial (VMH), but not in lateral (LH) hypothalamus. Consistently, food deprivation lowered, while refeeding normalized endogenous cAMP content in DMH and VMH, but not in LH areas. No significant effect of adenosine-3',5'-cyclic monophosphorothioate Rp-isomer (Rp-cAMP, cAMP antagonist) was observed on hypothalamic PKA activity, schedule-induced, or NPY-induced food intake. These findings suggest that the increase in cAMP level and PKA activity in DMH and VMH areas may trigger a satiety signal.

Topics: Animals; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Eating; Enzyme Activation; Feeding Behavior; Hypothalamus; Male; Neuropeptide Y; Radioimmunoassay; Rats; Rats, Sprague-Dawley; Thionucleotides; Time Factors

We have previously demonstrated that neuropeptide Y (NPY) inhibits depolarization-stimulated catecholamine synthesis in rat pheochromocytoma (PC12) cells differentiated to a sympathetic neuronal phenotype with nerve growth factor (NGF). The present study uses multiple selective Ca2+ channel and protein kinase agonists and antagonists to elucidate the mechanisms by which NPY modulates catecholamine synthesis as determined by in situ measurement of DOPA production in the presence of the decarboxylase inhibitor m-hydroxybenzylhydrazine (NSD-1015). The L-type Ca2+ channel blocker nifedipine inhibited the depolarization-induced stimulation of DOPA production by approximately 90% and attenuated the inhibitory effect of NPY. In contrast, the N-type Ca2+ channel blocker omega-conotoxin GVIA inhibited neither the stimulation of DOPA production nor the effect of NPY. Antagonism of Ca2+/calmodulin-dependent protein kinase (CaM kinase) greatly inhibited the stimulation of DOPA production by depolarization and prevented the inhibitory effect of NPY, whereas alterations in the cyclic AMP-dependent protein kinase pathway modulated DOPA production but did not prevent the effect of NPY. Stimulation of Ca2+/phospholipid-dependent protein kinase (PKC) with phorbol 12-myristate 13-acetate (PMA) did not affect the basal rate of DOPA production in NGF-differentiated PC12 cells but did produce a concentration-dependent inhibition of depolarization-stimulated DOPA production. In addition, NPY did not produce further inhibition of DOPA production in the presence of PMA, and the inhibition by both PMA and NPY was attenuated by the specific PKC inhibitor chelerythrine. These results indicate that NPY inhibits Ca2+ influx through L-type voltage-gated Ca2+ channels, possibly through a PKC-mediated pathway, resulting in attenuation of the activation of CaM kinase and inhibition of depolarization-stimulated catecholamine synthesis.

Topics: 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; Adenine; Animals; Calcium Channel Blockers; Calcium Channels; Calcium-Calmodulin-Dependent Protein Kinases; Carcinogens; Catecholamines; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Egtazic Acid; Enzyme Inhibitors; Imidazoles; Ion Channel Gating; Isoquinolines; Neuropeptide Y; Nifedipine; omega-Conotoxin GVIA; PC12 Cells; Peptides; Piperazines; Protein Kinase C; Protein Kinases; Protein Synthesis Inhibitors; Rats; Tetradecanoylphorbol Acetate; Thionucleotides

The effect of neuropeptide Y (NPY) on cellular adenosine 3',5'-cyclic monophosphate (cAMP) contents and macromolecule permeability was studied in cultured monolayers of microvascular coronary endothelial cells from rat. Macromolecule permeability was continuously determined as passage of albumin across the monolayers. NPY (10(-10)-10(-7) M) decreased albumin flux and cellular cAMP content in a dose-dependent manner, with a half-maximal effect on albumin flux at 1.4 x 10(-9) M and on cAMP contents at 0.7 x 10(-9) M. A maximum effect of NPY was observed at 10(-7) M, decreasing albumin flux by 71 +/- 8% and cellular cAMP contents by 80 +/- 9% (mean +/- SD, n = 6, P < 0.05) compared with control. The effect of NPY on albumin flux was not altered in the presence of 10(-5) M indomethacin (an inhibitor of cyclooxygenase) and 10(-5) M NG-nitro-L-arginine (an inhibitor of nitric oxide synthase). NPY (10(-7) M) also antagonized the increase of albumin flux and cAMP content induced by 10(-6) M isoproterenol. Pretreatment of endothelial monolayers with pertussis toxin (1 microgram/ml for 2 h) abolished the effect of NPY on albumin flux and cAMP contents. This study shows that NPY can modulate macromolecule permeability of endothelial monolayers by reducing the cellular cAMP contents. Together with the effect of pertussis toxin, the data suggest that NPY exerts its antiadrenergic effect on cAMP metabolism and endothelial barrier function by receptors linked to adenylyl cyclase via an inhibitory guanosine-binding protein in coronary endothelial cells.

Topics: Adenylate Cyclase Toxin; Animals; Capillary Permeability; Cells, Cultured; Coronary Vessels; Cyclic AMP; Endothelium, Vascular; Enzyme Inhibitors; Isoproterenol; Macromolecular Substances; Male; Neuropeptide Y; Nitroarginine; Pertussis Toxin; Rats; Rats, Wistar; Thionucleotides; Virulence Factors, Bordetella