preproenkephalin and Chronic-Disease

The Fischer 344 (F344) rat strain differs from the Lewis strain in the response to neuropathic pain. Recently, we found that F344 rats totally recover from mechanical allodynia induced by chronic constriction injury (CCI) of the sciatic nerve 28 days after surgery whereas Lewis rats are initiating their recovery at this time point. Thus, the use of this neuropathic pain model in these different rat strains constitutes a good strategy to identify possible target genes involved in the development of neuropathic pain. Since differences between Lewis and F344 rats in their response to pain stimuli in acute pain models have been related to differences in the endogenous opioid and noradrenergic systems, we aimed to determine the levels of expression of key genes of both systems in the spinal cord and dorsal root ganglia (DRG) of both strains 28 days after CCI surgery. Real time RT-PCR revealed minimal changes in gene expression in the spinal cord after CCI despite the strain considered, but marked changes in DRG were observed. A significant upregulation of prodynorphin gene expression occurred only in injured DRG of F344 rats, the most resistant strain to neuropathic pain. In addition, we found a significant downregulation of tyrosine hydroxylase and proenkephalin gene expression levels in both strains whereas delta-opioid receptor was found to be significantly downregulated only in injured DRG of Lewis rats although the same trend was observed in F344 rats. The data strongly suggest that dynorphins could be involved in strain differences concerning CCI resistance.

Topics: Animals; Chronic Disease; Denervation; Disease Models, Animal; Down-Regulation; Dynorphins; Enkephalins; Ganglia, Spinal; Gene Expression Regulation; Hyperalgesia; Ligation; Male; Neurons, Afferent; Norepinephrine; Peripheral Nerve Injuries; Peripheral Nerves; Peripheral Nervous System Diseases; Protein Precursors; Rats; Rats, Inbred F344; Rats, Inbred Lew; Receptors, Opioid, delta; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Species Specificity; Spinal Cord; Tyrosine 3-Monooxygenase

To provide a sound cell source for further ex-vivo gene therapy for chronic pain, we attempt to develop an immortalized rat astrocyte cell line that expresses enkephalin regulated by doxycycline.. Retrovirus infection method was employed to develop an immortalized rat astrocyte cell line that could express enkephalin regulated by doxycycline. The hPPE gene expression level of immoralized astroyte cells (IAC)/ hPPE was detected by RT-PCR, indirect immunofluorescence staining and radioimmunoassay.. IAC carrying Tet-on system transfected with preproenkephalin gene could secrete enkephalin that was regulated by doxycycline in a dose-dependent manner and hPPE gene activation could be repeated in on-off-on cycles through administration or removal of doxycycline.. An immortalized rat astrocyte cell line that secrete enkephalin under the control of doxycycline is established successfully, which provides a research basis for transgenic cell transplantation for analgesia.

Topics: Animals; Anti-Bacterial Agents; Astrocytes; Cell Line, Transformed; Chronic Disease; Doxycycline; Enkephalins; Genetic Therapy; Genetic Vectors; Neurotransmitter Agents; Pain Management; Protein Precursors; Rats; Retroviridae

To observe the changes of enkephalin mRNA and prodynorphin mRNA in hippocampus of rats induced by chronic immobilization stress.. Thirty rats were randomly divided into three groups of 10 each: the normal control group (group A), the group induced by chronic immobilization stress for 7 d (group B) and the group induced by chronic immobilization stress for 21 d (group C). The changes of the enkephalin mRNA and prodynorphin mRNA in the rat hippocampus were detected by reverse transcription-polymerase chain reaction (RT-PCR).. Expression levels of enkephalin mRNA and prodynorphin mRNA in rat hippocampus were significantly increased under chronic immobilization stress, and the expression of prodynorphin mRNA in the rat hippocampus in group C was remarkably higher than that in group B (0.624 +/- 0.026; n = 5; P<0.01).. The increased enkephalin mRNA and prodynorphin mRNA gene expressions in rat hippocampus were involved in chronic stress.

Topics: Animals; Chronic Disease; Enkephalins; Gene Expression; Hippocampus; Male; Protein Precursors; Rats; Rats, Sprague-Dawley; Restraint, Physical; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Stress, Physiological

While levodopa-induced neurochemical changes have been studied in animal models of Parkinson's disease, very little is known regarding the effects of levodopa administration in normal animals. The present study investigates the effects normal and MPTP-lesioned mice chronically treated with two different doses of levodopa. We assess changes in striatal dopamine (DA) receptor binding, striatal DA receptor mRNA levels and striatal neuropeptide precursor levels (preproenkephalin-A [PPE-A]; preprotachykinin [PPT]; preproenkephalin-B [PPE-B]). The extent of the lesion was measured by striatal DA transporter binding and stereological estimation of the number of tyrosine hydroxylase immunoreactive neurones in the substantia nigra pars compacta (SNc). In non-lesioned animals, chronic levodopa treatment induced an increase in PPE-A mRNA, whereas both D3R binding and PPE-B mRNA levels were dramatically increased in the lesioned animals in a dose dependent manner. The present results show that chronic levodopa administration may induce pathophysiological changes, even in the absence of a lesion of the nigro-striatal pathway, suggesting that the sensitization process involves predominantly the indirect striatofugal pathway in non-lesioned animals, whereas the direct pathway is primarily involved in lesioned animals.

Topics: 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine; Animals; Antiparkinson Agents; Binding, Competitive; Chronic Disease; Corpus Striatum; Disease Models, Animal; Dopamine Plasma Membrane Transport Proteins; Enkephalins; Levodopa; Male; Membrane Glycoproteins; Membrane Transport Proteins; Mice; Mice, Inbred C57BL; Nerve Tissue Proteins; Neural Pathways; Neurons; Parkinsonian Disorders; Protein Precursors; Receptors, Dopamine D1; Receptors, Dopamine D2; Receptors, Dopamine D3; RNA, Messenger; Substantia Nigra; Tachykinins; Tyrosine 3-Monooxygenase

There is evidence that suggests that increased corticotropin-releasing hormone (CRH) release in the central nucleus of the amygdala underlies the anxiogenic and stress-like consequences of withdrawal that are common in phenomenology to all drugs of abuse. The present studies were undertaken to determine levels of CRH mRNA in the amygdala, and also in the hypothalamus, frontal cortex and brainstem after short-term (2 days) and intermediate-term (10 days) cocaine withdrawal (with continued saline injections) from chronic (14 days) 'binge' pattern cocaine administration (3 x 15 mg/kg per day at hourly intervals). Confirming our recent finding of an activation of stress responsive hypothalamic-pituitary-adrenal activity during early cocaine withdrawal, there was a significant elevation of plasma corticosterone level after 2-day cocaine withdrawal. There was also a significant elevation of CRH mRNA levels in the amygdala, but not in the hypothalamus, frontal cortex or brainstem after 2-day cocaine withdrawal. A negative correlation between amygdalar CRH mRNA and plasma corticosterone levels was found in the 2-day cocaine withdrawn rats but not in control rats, suggesting that CRH neurons in the amygdala may be differentially responsive to glucocorticoids after chronic cocaine exposure and withdrawal. There were no changes in either plasma corticosterone or amygdalar CRH mRNA levels after 10-day cocaine withdrawal. Our findings of an increase in amygdalar CRH gene expression during early cocaine withdrawal support a potentially important role for amygdalar CRH activity in the anxiogenic and aversive consequences of withdrawal from cocaine during a time when humans are most subject to relapse.

Topics: Amygdala; Animals; Brain Stem; Chronic Disease; Cocaine; Cocaine-Related Disorders; Corticosterone; Corticotropin-Releasing Hormone; Dopamine Uptake Inhibitors; Enkephalins; Frontal Lobe; Gene Expression; Hypothalamo-Hypophyseal System; Male; Pituitary-Adrenal System; Protein Precursors; Rats; Rats, Inbred F344; RNA, Messenger; Substance Withdrawal Syndrome

Pancreatic intraductal neoplasia (PanIN) is thought to be the precursor to infiltrating pancreatic ductal adenocarcinoma. We have previously shown that the preproenkephalin (ppENK) and p16 genes are aberrantly methylated in pancreatic adenocarcinoma. In this study we define the methylation status of the ppENK and p16 genes in various grades of PanINs. One hundred seventy-four samples (28 nonneoplastic pancreatic epithelia, 7 reactive epithelia, 29 PanIN-1A, 48 PanIN-1B, 27 PanIN-2, 14 PanIN-3, 15 invasive ductal adenocarcinomas, and 6 miscellaneous pancreatic neoplasms) were microdissected from 29 formalin-fixed paraffin-embedded surgically resected pancreata, and were analyzed by methylation-specific polymerase chain reaction. Fourteen of 15 (93.3%) invasive pancreatic ductal adenocarcinomas showed methylation of the ppENK gene and 4 of 15 (26.7%) showed methylation of the p16 gene. Nonneoplastic pancreatic epithelia did not harbor methylation of either gene. The prevalence of methylation of the ppENK gene increased significantly with increasing PanIN grade. A similar nonsignificant trend was noted for p16 methylation. Aberrant methylation of the ppENK gene was found in 7.7% of PanIN-1A, 7.3% of PanIN-1B, 22.7% of PanIN-2, and 46.2% of PanIN-3. Aberrant methylation of the p16 gene was found in 12% of PanIN-1A, 2.6% of PanIN-1B, 4.5% of PanIN-2, and 21.4% of PanIN-3. All but one of the PanINs from the 14 pancreata without pancreatic carcinoma was unmethylated with respect to either the p16 or ppENK gene. Our results suggest that methylation-related inactivation of the ppENK and p16 genes is an intermediate or late event during pancreatic carcinogenesis. Because aberrant methylation of ppENK or p16 was more often detected in similar grade PanINs from patients with pancreatic carcinoma than in those with other pancreatic diseases, it may be a useful indicator of the potential malignancy of epithelial cells of the pancreas.

Topics: Aged; Aged, 80 and over; Carcinoma, Pancreatic Ductal; Chronic Disease; Cyclin-Dependent Kinase Inhibitor p16; DNA Methylation; DNA, Neoplasm; Enkephalins; Epithelium; Female; Humans; Male; Middle Aged; Neoplasm Invasiveness; Pancreas; Pancreatic Neoplasms; Pancreatitis; Protein Precursors

The functional interactions between the endogenous cannabinoid and opioid systems were evaluated in pre-proenkephalin-deficient mice. Antinociception induced in the tail-immersion test by acute Delta9-tetrahydrocannabinol was reduced in mutant mice, whereas no difference between genotypes was observed in the effects induced on body temperature, locomotion, or ring catalepsy. During a chronic treatment with Delta9-tetrahydrocannabinol, the development of tolerance to the analgesic responses induced by this compound was slower in mice lacking enkephalin. In addition, cannabinoid withdrawal syndrome, precipitated in Delta9-tetrahydrocannabinol-dependent mice by the injection of SR141716A, was significantly attenuated in mutant mice. These results indicate that the endogenous enkephalinergic system is involved in the antinociceptive responses of Delta9-tetrahydrocannabinol and participates in the expression of cannabinoid abstinence.

Topics: Acute Disease; Analysis of Variance; Animals; Autoradiography; Behavior, Animal; Body Temperature; Body Weight; Brain; Chronic Disease; Dronabinol; Drug Tolerance; Enkephalins; Hyperalgesia; Mice; Mice, Inbred C57BL; Mice, Knockout; Piperidines; Protein Precursors; Psychotropic Drugs; Pyrazoles; Receptors, Cannabinoid; Receptors, Drug; Rimonabant; Substance Withdrawal Syndrome

Topics: Animals; beta-Endorphin; Chronic Disease; Enkephalin, Methionine; Enkephalins; Gene Transfer Techniques; Genetic Therapy; Genetic Vectors; Humans; Mice; Pain Management; Protein Precursors; Simplexvirus; Spinal Cord

This study examined the extent of striatal dopamine (DA) denervation and coincident expression of preproenkephalin (PPE) mRNA in monkeys made parkinsonian by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) administration. Some animals (n = 4) became moderately parkinsonian after receiving large doses of MPTP over short periods of time and were symptomatic for only a short period of time (1-3 months; acute parkinsonian group). Other animals became moderately parkinsonian after receiving either escalating doses of MPTP over long periods (4-6 months; n = 5) or a high dose of MPTP over a short period (<1 month; n = 1) and remained symptomatic for an extended period (>8 months; chronic parkinsonian group). Despite similar symptomatology and similar degrees of striatal DA denervation at the time of their deaths, only acute parkinsonian animals had significantly increased PPE expression in sensorimotor striatal regions. PPE expression in chronic parkinsonian animals was either not changed or significantly decreased in most striatal regions. These findings suggest that the duration and not the extent of striatal DA denervation is a critical factor in modulating changes in striatal PPE expression. Furthermore, these results question the role of increased activity in the enkephalin-containing indirect striatopallidal pathway in the expression of parkinsonian symptoms.

Topics: Acute Disease; Animals; Autoradiography; Behavior, Animal; Chronic Disease; Corpus Striatum; Enkephalins; Gene Expression Regulation; Globus Pallidus; In Situ Hybridization; Macaca fascicularis; Male; Mazindol; Neural Pathways; Parkinson Disease, Secondary; Protein Precursors

To evaluate whether the endogenous opioid system is activated in the higher brain centre while a chronic resistance to airflow, we examined changes of mRNAs for preproenkephalin (PPE)-A, which is a precursor of enkephalin, and for 70 kD heat shock protein (HSP70) in the cerebral cortex of rat brain during chronic tracheal stenosis. Northern blot revealed that PPE-A mRNA was induced at 3 days of airway stenosis. In situ hybridization revealed that PPE-A mRNA was gradually induced in frontal cortex. The significant induction of PPE-A mRNA was observed at 3 and 7 days. However, no significant induction of HSP70 gene was observed. These results suggest that the endogenous opioid system may be at work as an important compensatory mechanism to reduce the respiratory sensation during chronic respiratory stress.

Topics: Animals; Base Sequence; Blotting, Northern; Cerebral Cortex; Chronic Disease; Enkephalins; Gene Expression; In Situ Hybridization; Male; Molecular Sequence Data; Protein Precursors; Rats; Rats, Sprague-Dawley; Respiratory Mechanics; RNA; Tidal Volume; Tracheal Stenosis