Brain-derived neurotrophic factor protects serotonergic neurons against 3,4-methylenedioxymethamphetamine ("Ecstasy") induced cytoskeletal damage.

3,4-Methylenedioxymethamphetamine (MDMA, "Ecstasy") use has been linked to persistent alterations of the brain serotonergic (5-HT) system in animal and human studies, but the molecular underpinnings are still unclear. Cytoskeletal structures such as neurofilament light chain (NfL) are promising markers of drug-induced brain toxicity and may be involved in MDMA neurotoxicity. The brain-derived neurotrophic factor (BDNF) promotes the growth and sprouting of 5-HT neurons and its differential response to MDMA administration was suggested to mediate dose- and region-dependent 5-HT damage by MDMA. However, the role of BDNF pre-treatment in preventing MDMA neurotoxicity and the potential effects of MDMA on NfL are still elusive. Therefore, a differentiated 5-HT neuronal cell line obtained from rat raphe nucleus (RN46A) was treated in vitro with either MDMA, BDNF, MDMA + BDNF, or vehicle. Cell viability (measured by MTT) and intracellular NfL levels (immunocytochemistry assay) were reduced by MDMA, but partially rescued by BDNF co-treatment. Our findings confirmed that BDNF levels can influence MDMA-induced 5-HT damage, and support BDNF to be a crucial target for neuroprotective interventions of the 5-HT system. We also provide evidence on the sensitivity of NfL to MDMA neurotoxicity, with potential implications for in-vivo monitoring of drug-induced neurotoxicity.

Early social isolation differentially affects the glucocorticoid receptor system and alcohol-seeking behavior in male and female Marchigian Sardinian alcohol-preferring rats.

Adverse early life experiences during postnatal development can evoke long-lasting neurobiological changes in stress systems, thereby affecting subsequent behaviors including propensity to develop alcohol use disorder. Here, we exposed genetically selected male and female Marchigian Sardinian alcohol-preferring (msP) and Wistar rats to mild, repeated social deprivation from postnatal day 14 (PND14) to PND21 and investigated the effect of the early social isolation (ESI) on the glucocorticoid receptor (GR) system and on the propensity to drink and seek alcohol in adulthood. We found that ESI resulted in higher levels of GR gene and protein expression in the prefrontal cortex (PFC) in male but not female msP rats. In female Wistars, ESI resulted in significant downregulation of Nr3c1 mRNA levels and lower GR protein levels. In male and female msP rats, plasma corticosterone levels on PND35 were similar and unaffected by ESI. Wistar females exhibited higher levels of corticosterone compared with males, independently from ESI. In alcohol self-administration experiments we found that the pharmacological stressor yohimbine (0.0, 0.312, 0.625, and 1.25 mg/kg) increased alcohol self-administration in both rat lines, regardless of ESI. After extinction, 0.625 mg/kg yohimbine significantly reinstated alcohol seeking in female rats only. ESI enhanced reinstatement in female msP rats. Overall, the present results indicate that repeated social deprivation during the third week of postnatal life affects GR expression in a strain- and sex-dependent manner: such effect may contribute, at least partially, to the heightened sensitivity of female msP rats to the effects of yohimbine-induced alcohol seeking.

The effects of nonsteroidal anti-inflammatory drugs on clinical outcomes, synovial fluid cytokine concentration and signal transduction pathways in knee osteoarthritis. A randomized open label trial.

OBJECTIVE: We investigated the effects of celecoxib, diclofenac, and ibuprofen on the disease-specific quality of life, synovial fluid cytokines and signal transduction pathways in symptomatic knee osteoarthritis (OA). DESIGN: Ninety patients scheduled for a total knee arthroplasty (TKA) were randomized to six groups that were treated with low and high dosages of celecoxib, diclofenac or ibuprofen. At the time of the first admission (T0) and at surgery (T1 = 14 days after beginning of the nonsteroidal anti-inflammatory drugs (NSAIDs)), samples of knee synovial fluid were obtained from each patient for analysis. During the surgery the synovial tissue was harvested from the knee of patients. The Western Ontario and McMaster universities (WOMAC) score was used to evaluate the patient disease-specific quality of life at T0 and T1. Microarray tests performed at T0 and T1 were used to evaluate the effects of NSAIDs on Tumor necrosis factor (TNF)-alpha, Interleukin-6 (IL-6), IL8 and Vascular endothelial growth factor (VEGF) concentration in the synovial fluid. Western blot assays evaluated the effects of NSAIDs on MAP kinase (MAPK) signal transduction pathway in the synovial membrane. RESULTS: NSAID treatment induced a statistically significant improvement in the WOMAC score and a statistically significant decrease in the IL-6, VEGF and TNF-alpha concentration in the synovial fluid. Higher dosages of NSAIDs provided a greater improvement in the disease-specific quality of life of patients and lower concentrations of pro-inflammatory cytokines in the synovial fluid. Inhibition of MAPKs was noted after NSAID treatment. CONCLUSION: Short-term NSAID treatment improves the patient disease-specific quality of life with a parallel decrease in pro-inflammatory synovial fluid cytokine levels in knee OA. Signal transduction pathways may be involved in regulating the anti-inflammatory effects of NSAIDs. ClinicalTrial.gov: NCT01860833.

Pin1 contribution to Alzheimer's disease: transcriptional and epigenetic mechanisms in patients with late-onset Alzheimer's disease.

BACKGROUND: Neurofibrillary tangles and senile plaques are hallmarks of Alzheimer's disease (AD) although the molecular basis of their coexistence remains elusive. The peptidyl-prolyl cis/trans isomerase Pin1 acts on both tau and amyloid precursor protein to regulate their functions by influencing tau phosphorylation and amyloid precursor protein processing. OBJECTIVE: In order to identify potential biomarkers for AD in easily accessible cells and to gain insight into the relationship between the brain and peripheral compartments in AD pathology, we investigated Pin1 expression and activity in the peripheral blood mononuclear cells of subjects with late-onset AD (LOAD) and age-matched controls (CT). METHODS: Gene and protein expression, promoter methylation, Ser(16) phosphorylation and activity of Pin1 were evaluated in 32 samples from subjects with LOAD and in 28 samples from CT. RESULTS: In LOAD subjects, there was a statistically significant reduction in Ser(16) phosphorylation (-30%; p = 0.041) and promoter methylation (-8%; p = 0.001), whereas Pin1 expression was significantly increased (+74%; p = 0.018). CONCLUSION: The modifications of Pin1 found in LOAD subjects support its involvement in the pathogenesis of the disease with an important role being played by epigenetic mechanisms.

Ethmoidal adenocarcinoma with lung metastases: diagnosis and multimodal treatment.

We report a case of 68-year-old patient underwent a magnetic resonance imaging (MRI) of the skull and a computed tomography (CT) of the thorax for rhinorrhea and dyspnea. The MRI showed an irregular ethmoidal lesion and the CT of the thorax underlined a solid nodular neoformation in the upper right pulmonary lobe. The patient underwent rhinoscopy with biopsies that showed an ethmoidal adenocarcinoma; excision of the tumour was carried out via trans-sphenoid. After one month the patient underwent wedge-resections in video-thoracoscopy (VATS). Perioperative histologic examination revealed a lung metastases due to an adenocarcinoma of the ethmoid. The patient was treated with chemotherapy and did not show relapses after 12 months from VATS.

Dynorphinergic system alterations in the corticostriatal circuitry of neuropathic mice support its role in the negative affective component of pain.

The dynorphinergic system is involved in pain transmission at spinal level, where dynorphin exerts antinociceptive or pronociceptive effects, based on its opioid or non-opioid actions. Surprisingly, little evidence is currently available concerning the supraspinal role of the dynorphinergic system in pain conditions. The present study aimed to investigate whether neuropathic pain is accompanied by prodynorphin (Pdyn) and κ-opioid receptor (Oprk1) gene expression alterations in selected mouse brain areas. To this end, mice were subjected to chronic constriction injury of the right sciatic nerve and neuropathic pain behavioral signs were ascertained after 14 days. At this interval, a marked increase in Pdyn mRNA in the anterior cingulate cortex (ACC) and prefrontal cortex (PFC) was observed. Oprk1 gene expression was increased in the PFC, and decreased in the ACC and nucleus accumbens (NAc). No changes were observed in the other investigated regions. Because of the relationship between dynorphin and the brain-derived neurotrophic factor, and the role of this neurotrophin in chronic pain-related neuroplasticity, we investigated brain-derived neurotrophic factor gene (Bdnf) expression in the areas showing Pdyn or Oprk1 mRNAs changes. Bdnf mRNA levels were increased in both the ACC and PFC, whereas no changes were assessed in the NAc. Present data indicate that the dynorphinergic system undergoes quite selective alterations involving the corticostriatal circuitry during neuropathic pain, suggesting a contribution to the negative affective component of pain. Moreover, parallel increases in Pdyn and Bdnf mRNA at cortical level suggest the occurrence of likely interactions between these systems in neuropathic pain maladaptive neuroplasticity.

Role of serotonin in the regulation of the dynorphinergic system by a kappa-opioid agonist and cocaine treatment in rat CNS.

It has been shown that chronic cocaine increases prodynorphin mRNA in the caudate putamen and decreases it in the hypothalamus. In addition, treatment with a kappa-opioid receptor agonist produced the opposite effect on prodynorphin gene expression in these brain regions and also evoked a decrease in the hippocampus. It is already known that kappa-opioid receptor agonists decrease the development of sensitization to some of the behavioral effects of cocaine. The serotonin system has also been shown to regulate dynorphin gene expression and a continuous infusion of fluoxetine induced prodynorphin gene expression in the same pattern as the kappa-opioid agonist (+)(5a,7a,8b)-N-methyl-N-[7-(1-pyrrolidinyl)-1 oxaspiro[4.5]dec-8-yl]-benzeneacetamide (U-69593) in the brain regions investigated. It is interesting to note that treatment with a continuous infusion of cocaine produced different effects on this parameter. To determine whether serotonin plays a role in the regulation of prodynorphin mRNA by kappa-opioid agonists or cocaine, rats were treated with the serotonin depleter parachloroamphetamine (PCA). Beginning 24 h later, rats were treated with the selective kappa-opioid agonist U-69593 for 5 days or continuously with cocaine for 7 days and prodynorphin mRNA was measured. Prodynorphin mRNA was decreased significantly in the hypothalamus, caudate putamen, and hippocampus of rats treated with a single injection of PCA. Subsequent to PCA administration the effects of U-69593 or cocaine on prodynorphin mRNA were differentially affected across brain regions. Prodynorphin gene expression was still increased by U-69593 treatment in the hypothalamus and decreased in the caudate putamen. Cocaine treatment still produced a decrease in this parameter in the hypothalamus and an increase in the caudate putamen. In contrast, in the hippocampus, the decrease in prodynorphin mRNA produced by U-69593 was no longer evident after PCA and cocaine, which previously had no effect, now increased it in the serotonin-depleted group. These findings suggest that serotonin is necessary to maintain normal levels of dynorphin mRNA in all of the investigated brain areas and that the regulation of prodynorphin mRNA expression by chronic treatment with a kappa-opioid receptor agonist or cocaine requires serotonin in the hippocampus, but not in the hypothalamus or caudate putamen.

From acute to chronic pain: tapentadol in the progressive stages of this disease entity.

OBJECTIVE: Chronic pain is now recognized as a neural disease, which results from a maladaptive functional and structural transformation process occurring over time. In its chronic phase, pain is not just a symptom but also a disease entity. Therefore, pain must be properly addressed, as many patients still report unsatisfactory pain control despite on-going treatment. The selection of the therapy - taking into account the pathophysiological mechanisms of pain - and the right timing can result in a successful analgesic outcome. This review will present the functional and structural modifications leading to chronification of pain, focusing on the role of tapentadol in this setting. MATERIALS AND METHODS: For inclusion in this review, research studies were retrieved via a keyword-based query of multiple databases (MEDLINE, Embase, Cochrane). The search was last updated in November 2016; no limitations were applied. RESULTS: Functional and structural abnormalities of the nervous system associated with pain chronification have been reported in several conditions, including osteoarthritis, chronic back pain, chronic pelvic pain and fibromyalgia. Correct identification and treatment of pain in recurrent/progressive stage is crucial to prevent chronification and related changes in neural structures. Among analgesic drugs, tapentadol, with its dual mechanism of action (opioid agonist and noradrenaline reuptake blocker), has recently resulted active in pain control at both central and spinal level. CONCLUSIONS: Tapentadol represents a suitable candidate for patients at early progressive stage of pain who have developed neuroplasticity with modification of pain pathways. The availability of different doses of tapentadol may help clinicians to tailor treatment based on the individual need of each patient, with the aim to enhance therapeutic appropriateness in the treatment of musculoskeletal and neuropathic pain.

N/OFQ system in brain areas of nerve-injured mice: its role in different aspects of neuropathic pain.

Several studies showed that chronic pain causes reorganization and functional alterations of supraspinal brain regions. The nociceptin-NOP receptor system is one of the major systems involved in pain control and much evidence also suggested its implication in stress, anxiety and depression. Therefore, we investigated the nociceptin-NOP system alterations in selected brain regions in a neuropathic pain murine model. Fourteen days after the common sciatic nerve ligature, polymerase chain reaction (PCR) analysis indicated a significant decrease of pronociceptin and NOP receptor mRNA levels in the thalamus; these alterations could contribute to the decrease of the thalamic inhibitory function reported in neuropathic pain condition. Nociceptin peptide and NOP mRNA increased in the anterior cingulate cortex (ACC) and not in the somatosensory cortex, suggesting a peculiar involvement of this system in pain regulating circuitry. Similarly to the ACC, an increase of nociceptin peptide levels was observed in the amygdala. Finally, the pronociceptin and NOP mRNAs decrease observed in the hypothalamus reflects the lack of hypothalamus-pituitary-adrenal axis activation, already reported in neuropathic pain models. Our data indicate that neuropathic pain conditions affect the supraspinal nociceptin-NOP system which is also altered in regions known to play a role in emotional aspects of pain.

Chronic and acute effects of 3,4-methylenedioxy-N-methylamphetamine ('Ecstasy') administration on the dynorphinergic system in the rat brain.

The prodynorphin system is implicated in the neurochemical mechanism of psychostimulants. Exposure to different drugs of abuse can induce neuroadaptations in the brain and affect opioid gene expression. The present study aims to examine the possibility of a common neurobiological substrate in drug addiction processes. We studied the effects of single and repeated 3,4-methylenedioxy-N-methylamphetamine ('Ecstasy') on the gene expression of the opioid precursor prodynorphin, and on the levels of peptide dynorphin A in the rat brain. Acute (8 mg/kg, intraperitoneally) 3,4-methylenedioxy-N-methylamphetamine markedly raised, two hours later, prodynorphin mRNA levels in the prefrontal cortex, and in the caudate putamen, whereas it decreased gene expression in the ventral tegmental area. Chronic (8 mg/kg, intraperitoneally, twice a day for 7 days) 3,4-methylenedioxy-N-methylamphetamine increased prodynorphin mRNA in the nucleus accumbens, hypothalamus and caudate putamen and decreased it in the ventral tegmental area. Dynorphin A levels increased after chronic treatment in the ventral tegmental area and decreased after acute treatment in the nucleus accumbens, prefrontal cortex and hypothalamus. These findings confirm the role of the dynorphinergic system in mediating the effects of drugs of abuse, such as 3,4-methylenedioxy-N-methylamphetamine, in various regions of the rat brain, which may be important sites for the opioidergic mechanisms activated by addictive drugs.

Alterations in prodynorphin gene expression and dynorphin levels in different brain regions after chronic administration of 14-methoxymetopon and oxycodone-6-oxime.

Previous studies showed that opioid drugs-oxycodone-6-oxime and 14-methoxy-5-methyl-dihydromorphinone (14-methoxymetopon)-produced less respiratory depressive effect and slower rate of tolerance and dependence, respectively. It was also reported that morphine decreased the prodynorphin gene expression in the rat hippocampus, striatum and hypothalamus. In this study, we determined the prodynorphin gene expression and dynorphin levels in selected brain regions of opioid tolerant rats. We found that in the striatum morphine decreased, while oxycodone-6-oxime increased and 14-methoxymetopon did not alter the prodynorphin gene expression. In the nucleus accumbens, morphine and oxycodone-6-oxime did not change, while 14-methoxymetopon increased the prodynorphin gene expression. In the hippocampus both oxycodone-6-oxime and 14-methoxymetopon enhanced, whereas morphine did not alter the prodynorphin gene expression. In the rat striatum only oxycodone-6-oxime increased dynorphin levels significantly in accordance with the prodynorphin mRNA changes. In the hippocampus both opioid agonists increased the dynorphin levels significantly similarly to the augmented prodynorphin gene expression. In ventral tegmental area only 14-methoxymetopon increased dynorphin levels significantly. In nucleus accumbens and the temporal-parietal cortex the changes in the prodynorphin gene expression and the dynorphin levels did not correlate. Since the endogenous prodynorphin system may play a modulatory role in the development of opioid tolerance, the elevated supraspinal dynorphin levels appear to be partly responsible for the reduced degree of tolerance induced by the investigated opioids.

Dynorphin and epilepsy.

Studies on dynorphin involvement in epilepsy are summarised in this review. Electrophysiological, biochemical and pharmacological data support the hypothesis that dynorphin is implicated in specific types of seizures. There is clear evidence that this is true for complex partial (limbic) seizures, i.e. those characteristic of temporal lobe epilepsy, because; (1) dynorphin is highly expressed in various parts of the limbic system, and particularly in the granule cells of the hippocampus; (2) dynorphin appears to be released in the hippocampus (and in other brain areas) during complex partial seizures; (3) released dynorphin inhibits excitatory neurotransmission at multiple synapses in the hippocampus via activation of kappa opioid receptors; (4) kappa opioid receptor agonists are highly effective against limbic seizures. Data on generalised tonic-clonic seizures are less straightforward. Dynorphin release appears to occur after ECS seizures and kappa agonists exert a clear anticonvulsant effect in this model. However, more uncertain biochemical data and lack of efficacy of kappa agonists in other generalised tonic-clonic seizure models argue that the involvement of dynorphin in this seizure type may not be paramount. Finally, an involvement of dynorphin in generalised absence seizures appears unlikely on the basis of available data. This may not be surprising, given the presumed origin of absence seizures in alterations of the thalamo-cortical circuit and the low representation of dynorphin in the thalamus. In conclusion, it may be suggested that dynorphin plays a role as an endogenous anticonvulsant in complex partial seizures and in some cases of tonic-clonic seizures, but most likely not in generalised absence. This pattern of effects may coincide with the antiseizure spectrum of selective kappa agonists.

What to Do, and What Not to Do, When Diagnosing and Treating Breakthrough Cancer Pain (BTcP): Expert Opinion.

Clinical management of breakthrough cancer pain (BTcP) is still not satisfactory despite the availability of effective pharmacological agents. This is in part linked to the lack of clarity regarding certain essential aspects of BTcP, including terminology, definition, epidemiology and assessment. Other barriers to effective management include a widespread prejudice among doctors and patients concerning the use of opioids, and inadequate assessment of pain severity, resulting in the prescription of ineffective drugs or doses. This review presents an overview of the appropriate and inappropriate actions to take in the diagnosis and treatment of BTcP, as determined by a panel of experts in the field. The ultimate aim is to provide a practical contribution to the unresolved issues in the management of BTcP. Five 'things to do' and five 'things not to do' in the diagnosis and treatment of BTcP are proposed, and evidence supporting said recommendations are described. It is the duty of all healthcare workers involved in managing cancer patients to be mindful of the possibility of BTcP occurrence and not to underestimate its severity. It is vital that all the necessary steps are carried out to establish an accurate and timely diagnosis, principally by establishing effective communication with the patient, the main information source. It is crucial that BTcP is treated with an effective pharmacological regimen and drug(s), dose and administration route prescribed are designed to suit the particular type of pain and importantly the individual needs of the patient.

Effects of acute ethanol exposure on class I HDACs family enzymes in wild-type and BDNF(+/-) mice.

BACKGROUND: Alterations of brain-derived neurotrophic factor (BDNF) have been associated with the development of addiction to different drugs of abuse, including ethanol (EtOH). EtOH exposure activates the BDNF-signaling cascade in dorsal striatum, which in turn affects further EtOH intake. Different alcohol exposures have been widely demonstrated to modulate chromatin remodeling, affecting histone acetylation/deacetylation balance. Recently, class I histone deacetylases (HDACs) inhibition has been reported to modulate BDNF mRNA expression and to attenuate morphological and behavioral phenomena related to EtOH exposure. However, the role played by different HDAC isoforms in EtOH-induced plasticity is still unclear. METHODS: We investigated the effects induced by acute EtOH exposure on the protein levels of class I HDAC 1-3 isoforms of wild-type (WT) and BDNF heterozygous mice (BDNF(+/-)), in nuclear and cytoplasmic extracts of specific brain regions associated with EtOH addiction. RESULTS: Nuclear HDAC 1-3 levels were markedly reduced after acute EtOH treatment in the caudate putamen (CPu) of WT mice only. Furthermore, CPu basal levels of nuclear HDAC isoforms were significantly lower in BDNF(+/-) mice compared to WT. With the exception of nuclear HDAC 3, no significant changes were observed after acute EtOH treatment in the prefrontal cortex (PFCx) of BDNF(+/-) and WT mice. In this area, the nuclear HDAC basal levels were significantly different between the two experimental groups. CONCLUSIONS: These results provide details about EtOH effects on class I HDAC isoforms and strongly support a correlation between BDNF and class I HDACs, suggesting a possible influence of BNDF on these enzymes.

The prevention of analgesic opioids abuse: expert opinion.

Opioids are drugs of reference for the treatment of moderate to severe pain. Their proper use and a periodic assessment of the patient are crucial to prevent misuse. A multidisciplinary group suggests strategies for all stakeholders involved in the management of pain and suggests the importance of the doctor-patient relationship.

Substance P is diminished and vasoactive intestinal peptide is augmented in psoriatic lesions and these peptides exert disparate effects on the proliferation of cultured human keratinocytes.

An involvement of neurogenic components in the pathogenesis of psoriatic lesions has been suggested and neuropeptides are thought to play a modulatory role in cutaneous inflammation. In this study, we evaluated the immunoreactivity of the neuropeptides vasoactive intestinal polypeptide (VIP) and substance P (SP) in the skin of patients with chronic plaque psoriasis, by immunohistochemistry and radioimmunoassay. No differences were observed, by immunohistochemistry, in the expression and localization of VIP and SP between psoriatic and normal skin. Using the radioimmunologic technique on whole skin homogenates, VIP levels were significantly increased in psoriatic lesions as compared to normal skin. By contrast, SP levels were significantly lower in lesional and non-lesional psoriatic skin than in normal skin. In addition, we examined the effect of VIP and SP on the proliferation of cultured normal human keratinocytes. VIP (1-28) (1 nM-1 microM) as well as VIP fragments (10-28) (1 nM-1 microM) and (22-28) (1 nM-1 microM) stimulated the proliferation of keratinocytes in a dose-dependent manner, whereas the VIP fragment (1-12) (1 nM-1 microM) was ineffective. The VIP antagonist (N-Ac-Tyr1, D-Phe2)-GRF (1-29)-NH2 (0.1 microM) significantly inhibited the VIP effect on keratinocytes. On the other hand, SP (0.1 microM) not only failed to stimulate keratinocyte growth, but also blocked the VIP-induced stimulation of these cells. The imbalance of cutaneous VIP and SP and their disparate effects on the proliferation of normal human keratinocytes in culture would suggest that these peptides are involved in the pathogenesis of psoriasis and may exert different modulatory activities in the mechanisms underlying the psoriatic lesion.

The effect of a paracetamol and morphine combination on dynorphin A levels in the rat brain.

The purpose of this study was to find out whether the combination of inactive doses of paracetamol (PARA) and morphine was able to change dynorphin (DYN) A levels, evaluated by radioimmunoassay, and whether naloxone or [(-)-2-(3 furylmethyl)-normetazocine] (MR 2266), a kappa-opioid antagonist, modifies or prevents the activity of this combination on nociception and on DYN levels. The work was suggested by our previous findings which demonstrated that inactive doses of PARA and morphine, when given in combination, share an antinociceptive effect, and that PARA, at antinociceptive doses, decreases DYN levels in the frontal cortex, thus indicating a selective action within the CNS. Our present results demonstrate that the combination of inactive doses of PARA (100 mg/kg) and morphine (3 mg/kg) is just as effective in decreasing the levels of DYN A as full antinociceptive doses of PARA or morphine alone in the frontal cortex of the rat. The values, expressed in pmol/g tissue, were: control = 2.83 +/- 0.20; paracetamol (100) = 2.60 +/- 0.23; morphine (3) = 2.73 +/- 0.24; paracetamol + morphine = 1.34 + 0.16 (P < 0.05). The decrease was partially antagonised by MR 2266, but not by naloxone, suggesting that the activity of PARA and morphine in combination on DYN A levels could be mediated, at least in part, through kappa-receptors, although other systems may be involved. On the other hand, both naloxone and MR 2266 prevented the antinociceptive effect of the combination in the hot plate test. All our experimental data suggest that PARA and morphine in combination exert their antinociceptive effect through the opioidergic system, which in turn may cause a decrease in DYN levels in the CNS of the rat.

Region-specific changes in prodynorphin mRNA and ir-dynorphin A levels after kindled seizures.

The opioid peptide dynorphin is thought to be implicated in specific types of seizures. In particular, complex partial seizures have been shown to cause release of dynorphin, activation of prodynorphin gene expression, and new peptide synthesis in the hippocampus. In this study, the kinetics of the seizure-induced changes in prodynorphin mRNA and ir-dynorphin A levels in the hippocampus have been compared with those induced in the temporal and frontal cortex, i.e., in other regions involved in the pathophysiology of complex partial seizures. Experiments have been run using kindling, one of the most valuable models of partial epilepsy. In the hippocampus (1) prodynorphin mRNA levels transiently increase (threefold) 1 h after kindled seizures, and return to baseline by 2 h, and (2) dynorphin A levels are slightly decreased at 1 h, but increase (twofold) at 2 h and return to baseline by 6 h. In the temporal and in the frontal cortex, a late (beginning at 2 h) and prolonged (up to 24 h) decrease in both prodynorphin mRNA and ir-dynorphin A levels have been observed. These data suggest that differential changes in dynorphin metabolism occur in different brain areas after seizures. The mechanisms and functional implications of this observation remain to be investigated.

Chronic intracerebroventricular cocaine differentially affects prodynorphin gene expression in rat hypothalamus and caudate-putamen.

We investigated the effects of sustained administration of cocaine on the regulation of prodynorphin gene expression in rat brain. Intracerebroventricular (i.c.v.) infusion of cocaine hydrochloride (30 micrograms/day) for 7 days, by means of osmotic minipumps, elicited a significant 35% decrease of prodynorphin mRNA levels in rat hypothalamus and increase (22%) in caudate-putamen. At the same time and in the same animals, no significant changes were detected in the hippocampus or in the nucleus accumbens. These results indicate that continuously infused cocaine is able to modulate expression of the prodynorphin gene in opposite directions or has no effect on prodynorphin expression, depending on the brain region analysed. Cocaine, as well as opiates, might activate specific neuronal pathways, shared by different classes of drugs of abuse, involving, at least in part, the endogenous opioid system.

Possible mediation of catecholaminergic pathways in the antinociceptive effect of an extract of Cannabis sativa L.

An extract of cannabis (5 and 15 mg/kg expressed as delta 9-THC) orally administered to rats caused an elevation of the nociceptive threshold (tail-flick latency and vocalization tests). Naloxone and naltrexone (blockers of mu-type opiate receptors) as well as MR 1452 (blocker of kappa opiate receptors) did not prevent the antinociceptive effect of cannabis when used at the dose of 2 mg/kg SC; only a high dose (10 mg/kg SC) of these narcotic antagonists partially blocked cannabis antinociception. ICI 154, 129, an antagonist of delta-type opiate receptors, failed to prevent the cannabis-induced rise in nociceptive threshold when used at a dose of 2 mg/kg SC but produced a significant effect at 10 mg/kg SC. While the role of opiate receptors does not seem fundamental to cannabis antinociception, the clear-cut effectiveness shown by 6-hydroxydopamine (a neurotoxin which causes a degeneration of catecholamine-containing terminals) in reducing cannabis antinociception is indicative of a participation of catecholamines in the phenomenon.