ucn-1028-c and Morphine-Dependence

Exposure to drugs of abuse or stress results in adaptation in the brain involving changes in gene expression and transcription factors. Morphine withdrawal modulates gene expression through various second-messenger signal transduction systems. Here, we investigated changes in activation of the transcription factor, cAMP-response element binding protein (CREB), in the hypothalamic paraventricular nucleus (PVN) and the kinases that may mediate the morphine withdrawal-triggered activation of CREB and the response of the hypothalamic-pituitary-adrenocortical (HPA) axis after naloxone-induced morphine withdrawal.. The effects of morphine dependence and withdrawal, phosphorylated CREB (pCREB), corticotrophin-releasing factor (CRF) expression in the PVN and HPA axis activity were measured using immunoblotting, immunohistochemistry and radioimmunoassay in controls and in morphine-dependent rats, withdrawn with naloxone and pretreated with vehicle, calphostin C, chelerythrine (inhibitors of protein kinase C (PKC) or SL-327 [inhibitor of extracellular signal regulated kinase (ERK) kinase]. In addition, changes in PKCα and PKCγ immunoreactivity were measured after 60 min of withdrawal.. In morphine-withdrawn rats, pCREB immunoreactivity was increased within CRF immunoreactive neurons in the PVN and plasma corticosterone levels were raised. SL-327, at doses that reduced the augmented pERK levels in the PVN, did not attenuate the rise in pCREB immunoreactivity or plasma corticosterone secretion. In contrast, PKC inhibition reduced the withdrawal-triggered rise in pCREB, pERK1/2 and corticosterone secretion.. PKC mediated, in part, both CREB activation and the HPA response to morphine withdrawal. The ERK kinase/ERK pathway might not be necessary for either activation of CREB or HPA axis hyperactivity.

Topics: Animals; Benzophenanthridines; Corticotropin-Releasing Hormone; Cyclic AMP Response Element-Binding Protein; Extracellular Signal-Regulated MAP Kinases; Hypothalamo-Hypophyseal System; Male; MAP Kinase Kinase Kinases; Mitogen-Activated Protein Kinase 3; Morphine; Morphine Dependence; Naloxone; Naphthalenes; Paraventricular Hypothalamic Nucleus; Phosphorylation; Pituitary-Adrenal System; Protein Kinase C; Rats; Rats, Sprague-Dawley; Substance Withdrawal Syndrome

Our previous studies have shown that morphine withdrawal induced hyperactivity of cardiac noradrenergic pathways. The purpose of the present study was to evaluate the effects of morphine withdrawal on site-specific phosphorylation of TH in the heart.. Dependence on morphine was induced by a 7-day s.c. implantation of morphine pellets in rats. Morphine withdrawal was precipitated on day 8 by an injection of naloxone (2 mg kg(-1)). TH phosphorylation was determined by quantitative blot immunolabelling using phosphorylation state-specific antibodies.. Naloxone-induced morphine withdrawal induced phosphorylation of TH at serine (Ser)40 and Ser31 in the right ventricle, associated with both an increase in total TH levels and an enhancement of TH activity. When HA-1004 (PK A inhibitor) was infused, concomitantly with morphine, it diminished the increase in noradrenaline turnover, total TH levels and TH phosphorylation at Ser40 in morphine-withdrawn rats. In contrast, the infusion of calphostin C (PKC inhibitor), did not modify the morphine withdrawal-induced increase in noradrenaline turnover and total TH levels. In addition, we show that the ability of morphine withdrawal to stimulate phosphorylation at Ser31 was reduced by SL327, an inhibitor of ERK 1/2 activation.. The present findings demonstrate that the enhancement of total TH levels and the increased phosphorylation state of TH during morphine withdrawal were dependent on PKA and ERK activities and suggest that these transduction pathways might contribute to the activation of the cardiac catecholaminergic neurons in response to morphine withdrawal.

Topics: Aminoacetonitrile; Animals; Cyclic AMP-Dependent Protein Kinases; Disease Models, Animal; Drug Implants; Isoquinolines; Male; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Morphine; Morphine Dependence; Myocardium; Naloxone; Naphthalenes; Narcotic Antagonists; Norepinephrine; Phosphorylation; Protein Kinase C-delta; Protein Kinase Inhibitors; Rats; Rats, Sprague-Dawley; Serine; Substance Withdrawal Syndrome; Sulfonamides; Tyrosine 3-Monooxygenase

Our previous studies have shown an enhanced activity of the noradrenergic system in the heart in rats withdrawn from morphine. In the current study, we examined the role of protein kinase A, protein kinase C and Ca(2+) entry through L-type Ca(2+) channels in naloxone-precipitated increase turnover of noradrenaline in the right and left ventricle. Chronic pretreatment for 7 days with the selective protein kinase A inhibitor, HA-1004 (N-(2' guanidinoethyl)-5-isoquinolinesulfonamide) concomitantly with morphine significantly antagonized the increase in normetanephrine/noradrenaline ratio (an index of noradrenaline turnover) observed in morphine withdrawn rats. However, the infusion of calphostin C (2-(12-(2-(benzoyloxy)propyl)-3,10-dihydro-4,9-dihydroxy-2,6,7,11-tetramethoxy-3,10-dioxo-1-perylenyl)-1 methylethy carbonic acid 4-hydroxyphenyl ester, a selective protein kinase C inhibitor) did not modify the morphine withdrawal-induced increase in noradrenaline turnover. In addition, when the selective L-type Ca(2+) channel antagonist, nimodipine, was infused it diminished the increased in noradrenaline turnover observed after naloxone administration to morphine dependent rats. Taken together, these data might indicate that protein kinase A activity is necessary for the enhancement of noradrenaline turnover during morphine withdrawal and that an up-regulated Ca(2+) system might contribute to the increase of noradrenaline turnover. The present finding suggests that protein kinase A and Ca(2+) influx through L-type Ca(2+) channels might contribute to the activation of noradrenergic system in the heart observed during morphine withdrawal.

Topics: Animals; Calcium Channels, L-Type; Calcium Signaling; Cyclic AMP-Dependent Protein Kinases; Drug Combinations; Drug Implants; Heart; Infusion Pumps, Implantable; Injections, Subcutaneous; Isoquinolines; Male; Morphine; Morphine Dependence; Naloxone; Naphthalenes; Nimodipine; Norepinephrine; Normetanephrine; Protein Kinase C; Rats; Rats, Sprague-Dawley; Signal Transduction; Substance Withdrawal Syndrome; Sulfonamides; Up-Regulation

The involvement of cyclic AMP-dependent protein kinase (PKA) and protein kinase C (PKC) in the modulation of naloxone-precipitated withdrawal jumping in morphine-dependent mice by diabetes was examined. Naloxone-precipitated withdrawal jumps were significantly less in morphine-dependent diabetic mice than in morphine-dependent non-diabetic mice. I.c.v. pretreatment with either calphostin C, a PKC inhibitor, or KT-5720, a PKA inhibitor, attenuated naloxone-precipitated withdrawal jumps in morphine-dependent non-diabetic mice. However, naloxone-precipitated withdrawal jumps in morphine-dependent diabetic mice were not attenuated by i.c.v. pretreatment with either calphostin C or KT5720. Moreover, i.c.v. pretreatment with phorbol-12,13-dibutyrate (PDBu), a PKC activator, attenuated naloxone-precipitated withdrawal jumps in morphine-dependent non-diabetic mice, but not in morphine-dependent diabetic mice. The noradrenaline (NA) turnover in the frontal cortex in morphine-dependent non-diabetic mice, but not in morphine-dependent diabetic mice, was significantly increased 5 min after administration of naloxone. Naloxone-induced enhancement of NA turnover in morphine-dependent non-diabetic mice, but not in morphine-dependent diabetic mice, was blocked by i.c.v. pretreatment with either calphostin C or KT5720 1 hr before naloxone challenge and blocked by PDBu 1 hr before the last injection of morphine. These results suggest that the co-activation of PKC and PKA is needed to elicit naloxone-precipitated withdrawal jumps and enhancement of turnover rate of NA in the frontal cortex in morphine-dependent non-diabetic mice. Furthermore, the attenuation of naloxone-precipitated withdrawal jumps in morphine-dependent diabetic mice may be due, in part, to the desensitization of mu-opioid receptors by the activation of PKC.

Topics: Animals; Behavior, Animal; Carbazoles; Carcinogens; Cyclic AMP-Dependent Protein Kinases; Diabetes Mellitus, Experimental; Enzyme Inhibitors; Frontal Lobe; Indoles; Male; Mice; Mice, Inbred ICR; Morphine; Morphine Dependence; Naloxone; Naphthalenes; Narcotic Antagonists; Narcotics; Norepinephrine; Phorbol 12,13-Dibutyrate; Protein Kinase C; Pyrroles; Substance Withdrawal Syndrome