Could Small Heat Shock Protein HSP27 Be a First-Line Target for Preventing Protein Aggregation in Parkinson's Disease?

Small heat shock proteins (HSPs), such as HSP27, are ubiquitously expressed molecular chaperones and are essential for cellular homeostasis. The major functions of HSP27 include chaperoning misfolded or unfolded polypeptides and protecting cells from toxic stress. Dysregulation of stress proteins is associated with many human diseases including neurodegenerative diseases, such as Parkinson's disease (PD). PD is characterized by the presence of aggregates of α-synuclein in the central and peripheral nervous system, which induces the degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNpc) and in the autonomic nervous system. Autonomic dysfunction is an important non-motor phenotype of PD, which includes cardiovascular dysregulation, among others. Nowadays, the therapies for PD focus on dopamine (DA) replacement. However, certain non-motor symptoms with a great impact on quality of life do not respond to dopaminergic drugs; therefore, the development and testing of new treatments for non-motor symptoms of PD remain a priority. Since small HSP27 was shown to prevent α-synuclein aggregation and cytotoxicity, this protein might constitute a suitable target to prevent or delay the motor and non-motor symptoms of PD. In the first part of our review, we focus on the cardiovascular dysregulation observed in PD patients. In the second part, we present data on the possible role of HSP27 in preventing the accumulation of amyloid fibrils and aggregated forms of α-synuclein. We also include our own studies, highlighting the possible protective cardiac effects induced by L-DOPA treatment through the enhancement of HSP27 levels and activity.

Cardiac Changes in Parkinson's Disease: Lessons from Clinical and Experimental Evidence.

Dysautonomia is a common non-motor symptom in Parkinson's disease (PD). Most dysautonomic symptoms appear due to alterations in the peripheral nerves of the autonomic nervous system, including both the sympathetic and parasympathetic nervous systems. The degeneration of sympathetic nerve fibers and neurons leads to cardiovascular dysfunction, which is highly prevalent in PD patients. Cardiac alterations such as orthostatic hypotension, heart rate variability, modifications in cardiogram parameters and baroreflex dysfunction can appear in both the early and late stages of PD, worsening as the disease progresses. In PD patients it is generally found that parasympathetic activity is decreased, while sympathetic activity is increased. This situation gives rise to an imbalance of both tonicities which might, in turn, promote a higher risk of cardiac damage through tachycardia and vasoconstriction. Cardiovascular abnormalities can also appear as a side effect of PD treatment: L-DOPA can decrease blood pressure and aggravate orthostatic hypotension as a result of a negative inotropic effect on the heart. This unwanted side effect limits the therapeutic use of L-DOPA in geriatric patients with PD and can contribute to the number of hospital admissions. Therefore, it is essential to define the cardiac features related to PD for the monitorization of the heart condition in parkinsonian individuals. This information can allow the application of intervention strategies to improve the course of the disease and the proposition of new alternatives for its treatment to eliminate or reverse the motor and non-motor symptoms, especially in geriatric patients.

Cardiac Noradrenaline Turnover and Heat Shock Protein 27 Phosphorylation in Dyskinetic Monkeys.

BACKGROUND: Autonomic dysfunction is a well-known dominant symptom in the advanced stages of Parkinson's disease. However, the role of cardiac sympathetic nerves still needs to be elucidated. OBJECTIVES: To evaluate cardiac sympathetic response in Parkinsonian and dyskinetic monkeys. METHODS: Adult male monkeys were divided into 1 of the following 3 groups: controls, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-treated monkeys, and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine+levodopa-treated animals. Noradrenaline, its metabolite normetanephrine, and phospho-Heat shock proten 27 (p-Hsp27) at serine 82 levels were analyzed in the left and right ventricles of the heart. Tyrosine hydroxylase immunohistochemistry was performed in the ventral mesencephalon. RESULTS: The results were the following: (1) 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine intoxication significantly increased normetanephrine levels and decreased noradrenaline turnover in the right ventricle without changes in the left ventricle; however, (2) levodopa treatment decreased noradrenaline levels and enhanced the normetanephrine/noradrenaline ratio in parallel with a very significant increase of Hsp27 activity in both ventricles. CONCLUSIONS: Levodopa treatment could induce protective cardiac effects through the increased Hsp27 activity. © 2019 International Parkinson and Movement Disorder Society.

Conditioned aversive memory associated with morphine withdrawal increases brain-derived neurotrophic factor in dentate gyrus and basolateral amygdala.

Morphine has been shown to increase the expression of brain-derived neurotrophic factor (BDNF) in the brain. However, little is known about the effect of conditioned naloxone-precipitated morphine withdrawal on BDNF and its precursor protein, proBDNF. We used the conditioned place aversion (CPA) paradigm to evaluate the role of corticotropin-releasing factor (CRF)/CRF1 receptor signaling on the BDNF expression and corticosterone plasma levels after CPA expression and extinction. Male mice were rendered dependent on morphine and injected acutely with naloxone before paired to confinement in a naloxone-associated compartment. The expression of BDNF and proBDNF in the dentate gyrus (DG) and basolateral amygdala (BLA) was measured in parallel with the corticosterone plasma levels with and without CRF1 receptor blockade. Mice subjected to conditioned naloxone-induced morphine withdrawal showed an increased expression of BDNF (in DG and BLA) in parallel with an enhancement of corticosterone plasma levels. These results demonstrated that BDNF expression together with the increased activity of hypothalamic-pituitary-adrenocortical (HPA) axis are critical to the acquisition of aversive memory. However, we have observed a decrease in corticosterone plasma levels and BDNF expression after CPA extinction reaffirming the importance of BDNF in the maintenance of aversive memory. In addition, the pre-treatment with the CRF1 receptor antagonist CP-154 526 before naloxone conditioning session impaired morphine withdrawal-induced aversive memory acquisition, the increased corticosterone plasma levels, and the expression of BDNF observed after CPA expression in the DG and BLA. Altogether, present results are suggesting a clear connection between HPA axis and BDNF in the formation and extinction of aversive memory.

Cardiac Protective Role of Heat Shock Protein 27 in the Stress Induced by Drugs of Abuse.

Heat shock proteins (HSP) are induced after different stress situations. Some of these proteins, particularly HSP-27, function as markers to indicate cellular stress or damage and protect the heart during addictive processes. Morphine withdrawal induces an enhancement of sympathetic activity in parallel with an increased HSP-27 expression and phosphorylation, indicating a severe situation of stress. HSP-27 can interact with different intracellular signaling pathways. Propranolol and SL-327 were able to antagonize the activation of hypothalamic-pituitary adrenal (HPA) axis and the phosphorylation of HSP-27 observed during morphine withdrawal. Therefore, ß-adrenergic receptors and the extracellular signal-regulated kinase (ERK) pathway would be involved in HPA axis activity, and consequently, in HSP-27 activation. Finally, selective blockade of corticotrophin releasing factor (CRF)-1 receptor and the genetic deletion of CRF1 receptors antagonize cardiac adaptive changes. These changes are increased noradrenaline (NA) turnover, HPA axis activation and decreased HSP-27 expression and phosphorylation. This suggests a link between the HPA axis and HSP-27. On the other hand, morphine withdrawal increases µ-calpain expression, which in turn degrades cardiac troponin T (cTnT). This fact, together with a co-localization between cTnT and HSP-27, suggests that this chaperone avoids the degradation of cTnT by µ-calpain, correcting the cardiac contractility abnormalities observed during addictive processes. The aim of our research is to review the possible role of HSP-27 in the cardiac changes observed during morphine withdrawal and to understand the mechanisms implicated in its cardiac protective functions.

Identification of Benzodiazepine Use Based on Dried Blood Stains Analysis.

Biological matrices are typically used in forensic toxicological or pharmacological analysis: mainly blood, vitreous humor or urine. However, there are many cases in which crimes are a consequence of drug intoxication or drug abuse and they are not closed because over the months or years the samples become altered or decomposed. A dried blood stains test (DBS-MS) has recently been proposed to be used in drug toxicology when blood is found at a crime scene. This test could help an investigator to reveal what a person had consumed before the perpetration of the crime. In order to check the possibilities of this test, we analyzed several dried blood stains located on a cotton fabric. Therefore, the aim of this study was to determine if the analysis of a dried blood spot located on a cotton fabric could be an alternate source of obtaining toxicological results, particularly regarding benzodiazepines. We splashed blood stains on cotton fabric with different concentrations of the following benzodiazepines: alprazolam, bromazepam, clonazepam, diazepam and lorazepam, which were dried for 96 h and subsequently quantified by high-performance liquid chromatography coupled mass spectrometry (HPLC-MS). Our results show that it is possible to identify several benzodiazepines contained in a cotton fabric blood stain; consequently, this method may add another sample option to the toxicological analysis of biological vestiges found at a crime scene.

Pregabalin and topiramate regulate behavioural and brain gene transcription changes induced by spontaneous cannabinoid withdrawal in mice.

This study examined the actions of pregabalin and topiramate on behavioural and gene transcription alterations induced by spontaneous cannabinoid withdrawal in mice. Tolerance was induced in mice by administration of CP-55,940 (0.5 mg/kg/12 hours; i.p.; 7 days). Behavioural assessment of spontaneous cannabinoid withdrawal was performed by measuring motor activity, somatic signs and anxiety-like behaviour on days 1 and 3 after cessation of treatment with CP-55,940. On days 1-3 of cannabinoid withdrawal, mice received pregabalin (40 mg/kg/12 hours; p.o.) or topiramate (50 mg/kg/12 hours; p.o.) and their actions on signs of withdrawal and anxiety-like behaviour were evaluated. The administration of CP-55,940 decreased rectal temperature and motor activity on day 1. On day 1 after interruption of cannabinoid administration, motor activity and the number of rearings increased compared with control group. Anxiety-like behaviour induced by cessation of cannabinoid treatment increased significantly on days 1 and 3 of withdrawal. The administration of pregabalin or topiramate blocked the motor signs and reduced significantly anxiety-like behaviour. Cannabinoid withdrawal decreased tyrosine hydroxylase (TH) gene expression in the ventral tegmental area and µ-opioid receptor gene expression in the nucleus accumbens (NAcc) and increased CB1 receptor gene expression in the NAcc. Treatment with topiramate or pregabalin blocked the decrease of TH and the increase of CB1 gene expressions induced by cannabinoid withdrawal. Both drugs failed to alter µ-opioid receptor gene expression. These results suggest that pregabalin and topiramate may result useful for the treatment of anxiety-like behaviour and motor symptoms associated with spontaneous cannabinoid withdrawal.

Cut-off value for ß-trace protein (ß-TP) as a rapid diagnostic of cerebrospinal fluid (CSF) leak detection.

Objective: To find an adequate cut-off point for beta trace protein (ß-TP) in nasal secretion (NS) and validate this diagnostic test with a large sample of patients. Likewise, we evaluated ß-TP test efficacy to confirm the cerebrospinal fluid (CSF) leakage closure after treatment. Methods: We performed a retrospective analysis with 207 samples from 162 patients with suspected CSF leakage received in the Hospital Universitario Virgen de la Arrixaca between 2010 and 2016. Twenty-five samples were included in the control group. Samples were obtained from NS through a swab to determine ß-TP using a nephelometry-based assay. Sensitivity, specificity, and area under the curve (AUC) for ß-TP in NS were assessed using the receiver operator characteristic (ROC) analysis. Results: Using imaging techniques, the diagnosis of CSF leak was confirmed in 57 patients (35.19%), while 105 had a negative diagnosis (64.81%). Patients with CSF leakage had significantly higher ß-TP values in NS (16.07 ± 16.94 mg/L, p < .001) than the control group (0.33 ± 0.12 mg/L) and patients without CSF leakage (0.61 ± 2.34 mg/L). Applying a 1 mg/L cut-off point resulted in 96.5% sensitivity and 97.1% specificity. Positive and negative predictive values (PPV and NPV) at this cut-off were 94.9% and 98.6%, respectively. Finally, this cut-off point yields a test efficacy for CSF leak diagnosis of 97% (95% CI 92.9-98.9). Conclusion: Our study has established a 1 mg/L ß-TP concentration in NS as a cut-off point for CSF leakage diagnosis with high sensibility and specificity. These results suggest that ß-TP analysis could be useful to check CSF leak resolution. Level of Evidence: 4.

Upregulation of Heat-Shock Protein (hsp)-27 in a Patient with Heterozygous SPG11 c.1951C>T and SYNJ1 c.2614G>T Mutations Causing Clinical Spastic Paraplegia.

We report a 49-year-old patient suffering from spastic paraplegia with a novel heterozygous mutation and analyzed the levels of heat shock proteins (hsp)-27, dopamine (DA), and its metabolites in their cerebrospinal fluid (CSF). The hsp27 protein concentration in the patient's CSF was assayed by an ELISA kit, while DA levels and its metabolites in the CSF, 3,4-dihydroxyphenylacetic acid (DOPAC), Cys-DA, and Cys-DOPA were measured by HPLC. Whole exome sequencing demonstrated SPG-11 c.1951C>T and novel SYNJ1 c.2614G>T mutations, both heterozygous recessive. The patient's DA and DOPAC levels in their CSF were significantly decreased (53.0 ± 6.92 and 473.3 ± 72.19, p < 0.05, respectively) while no differences were found in their Cys-DA. Nonetheless, Cys-DA/DOPAC ratio (0.213 ± 0.024, p < 0.05) and hsp27 levels (1073.0 ± 136.4, p < 0.05) were significantly higher. To the best of our knowledge, the c.2614G>T SYNJ1 mutation has not been previously reported. Our patient does not produce fully functional spatacsin and synaptojanin-1 proteins. In this line, our results showed decreased DA and DOPAC levels in the patient's CSF, indicating loss of DAergic neurons. Many factors have been described as being responsible for the increased cys-DA/DOPAC ratio, such as MAO inhibition and decreased antioxidant activity in DAergic neurons which would increase catecholquinones and consequently cysteinyl-catechols. In conclusion, haploinsufficiency of spatacsin and synaptojanin-1 proteins might be the underlying cause of neurodegeneration produced by protein trafficking defects, DA vesicle trafficking/recycling processes, autophagy dysfunction, and cell death leading to hsp27 upregulation as a cellular mechanism of protection and/or to balance impaired protein trafficking.

Naloxone-induced conditioned place aversion score and extinction period are higher in C57BL/6J morphine-dependent mice than in Swiss: Role of HPA axis.

Intense associative memories develop between drug-paired contextual cues and the drug withdrawal associated aversive feeling. They have been suggested to contribute to the high rate of relapse. Our study was aimed to elucidate the involvement of hypothalamic-pituitary-adrenocortical (HPA) axis activity in the expression and extinction of aversive memory in Swiss and C57BL/6J (B6) mice. The animals were rendered dependent on morphine by i.p. injection of increasing doses of morphine (10-60 mg/kg). The negative state associated with naloxone (1 mg/kg s.c.) precipitated morphine withdrawal was examined by using conditioned place aversion (CPA) paradigm. B6 mice obtained a higher aversion score and took longer to extinguish the aversive memory than Swiss mice. In addition, corticosterone levels were increased after CPA expression. Moreover, corticosterone levels were decreased during CPA extinction in Swiss mice without changes in B6 mice. Pre-treatment with the selective CRF1 receptor antagonist CP-154,526 before naloxone, impaired morphine-withdrawal aversive memory acquisition and decreased the extinction period. CP-154,526 also antagonized the increased levels of corticosterone observed after CPA expression in Swiss mice, without any changes in B6 mice. These results indicate that HPA axis could be a critical factor governing opioid withdrawal memory storage and retrieval, but in a strain or stock-specific manner. The differences observed between Swiss and B6 mice suggest that the treatment of addictive disorders should consider different individual predisposition to associate the aversive learning with the context.

Cardiac tyrosine hydroxylase activation and MB-COMT in dyskinetic monkeys.

The impact of age-associated disorders is increasing as the life expectancy of the population increments. Cardiovascular diseases and neurodegenerative disorders, such as Parkinson's disease, have the highest social and economic burden and increasing evidence show interrelations between them. Particularly, dysfunction of the cardiovascular nervous system is part of the dysautonomic symptoms of Parkinson's disease, although more studies are needed to elucidate the role of cardiac function on it. We analyzed the dopaminergic system in the nigrostriatal pathway of Parkinsonian and dyskinetic monkeys and the expression of some key proteins in the metabolism and synthesis of catecholamines in the heart: total and phosphorylated (phospho) tyrosine hydroxylase (TH), and membrane (MB) and soluble (S) isoforms of catechol-O-methyl transferase (COMT). The dopaminergic system was significantly depleted in all MPTP-intoxicated monkeys. MPTP- and MPTP + L-DOPA-treated animals also showed a decrease in total TH expression in both right (RV) and left ventricle (LV). We found a significant increase of phospho-TH in both groups (MPTP and MPTP + L-DOPA) in the LV, while this increase was only observed in MPTP-treated monkeys in the RV. MB-COMT analysis showed a very significant increase of this isoform in the LV of MPTP- and MPTP + L-DOPA-treated animals, with no significant differences in S-COMT levels. These data suggest that MB-COMT is the main isoform implicated in the cardiac noradrenergic changes observed after MPTP treatment, suggesting an increase in noradrenaline (NA) metabolism. Moreover, the increase of TH activity indicates that cardiac noradrenergic neurons still respond despite MPTP treatment.

Tyrosine hydroxylase phosphorylation after naloxone-induced morphine withdrawal in the left ventricle.

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 tyrosine hydroxylase (TH) phosphorylation in the rat left ventricle. Dependence on morphine was induced by a 7-day s.c. implantation of morphine pellets. Morphine withdrawal was precipitated on day 8 by an injection of naloxone (2 mg/kg, s.c.). TH phosphorylation was determined by quantitative blot immunolabelling using phosphorylation state-specific antibodies. Ninety min after naloxone administration to morphine-dependent rats there was an increase in phospho-Ser40-TH (139.0 +/- 13%, P < 0.05) and Ser31-TH (135.5 +/- 11%, P < 0.05) in the left ventricle which is associated with both an increase in total TH levels (114.4 +/- 4.6%, P < 0.05, P < 0.01) and an enhancement of TH activity (51.0 +/- 11 dm/microg protein, P < 0.001). When HA-1004 (40 nmol/day), inhibitor of cyclic AMP dependent protein kinase (PKA) was infused, concomitantly with morphine, it diminished the increase in noradrenaline (NA) turnover, total TH expression (95.76 +/- 4.1 %, P < 0.01) and TH phosphorylation at Ser40 (85.5 +/- 11%, P < 0.01) in morphine-withdrawn rats. In addition, we showed that the ability of morphine withdrawal to stimulate phosphorylation at serine 31 is reduced (101.7 +/- 7.7%, P < 0.05) by SL327 (100 mg/kg, i.p.), an inhibitor of extracellular signal-regulated kinase (ERK) activation. The present findings demonstrate that the enhancement of total TH expression and the increase of the phosphorylation state of TH during morphine withdrawal are dependent on PKA and ERK and suggest that these transduction pathways might contribute to the activation of the cardiac catecholaminergic neurons in response to morphine- withdrawal.

Liposome-Encapsulated Morphine Affords a Prolonged Analgesia While Facilitating Extinction of Reward and Aversive Memories.

Morphine is thoroughly used for pain control; however, it has a high addictive potential. Opioid liposome formulations produce controlled drug release and have been thoroughly tested for pain treatment although their role in addiction is still unknown. This study investigated the effects of free morphine and morphine encapsulated in unilamellar and multilamellar liposomes on antinociception and on the expression and extinction of the positive and negative memories associated with environmental cues. The hot plate test was used to measure central pain. The rewarding effects of morphine were analyzed by the conditioned-place preference (CPP) test, and the aversive aspects of naloxone-precipitated morphine withdrawal were evaluated by the conditioned-place aversion (CPA) paradigm. Our results show that encapsulated morphine yields prolonged antinociceptive effects compared with the free form, and that CPP and CPA expression were similar in the free- or encapsulated-morphine groups. However, we demonstrate, for the first time, that morphine encapsulation reduces the duration of reward and aversive memories, suggesting that this technological process could transform morphine into a potentially less addictive drug. Morphine encapsulation in liposomes could represent a pharmacological approach for enhancing extinction, which might lead to effective clinical treatments in drug addiction with fewer side effects.

Pharmacological modulation of the behavioral effects of social defeat in memory and learning in male mice.

RATIONALE: Previous studies have demonstrated that repeated social defeat (RSD) stress only induces cognitive deficits when experienced during adulthood. However, RSD increases cocaine-rewarding effects in adult and adolescent mice, inducing different expressions of proBDNF in the ventral tegmental area. OBJECTIVE: The aim of the present study was to evaluate the effect of cocaine administration in socially defeated adult or adolescent mice on learning, memory, and anxiety. Additionally, the role of BDNF was also studied. METHODS: Adolescent and young adult mice were exposed to four episodes of social defeat or exploration (control), being treated with a daily injection of four doses of saline or 1 mg/kg of cocaine 3 weeks after the last social defeat. Other groups were treated with the TrkB receptor antagonist ANA-12 during this 21-day period. After this treatment, their cognitive and anxiogenic profiles were evaluated, along with the expression of BDNF, pCREB, and pERK1/2 in the dentate gyrus (DG) and basolateral amygdala (BLA). RESULTS: Cocaine induced an increased expression of pCREB and BDNF in the DG and BLA only in defeated animals. Although RSD did not affect memory, the administration of cocaine induced memory impairments only in defeated animals. Defeated adult mice needed more time to complete the mazes, and this effect was counteracted by cocaine administration. RSD induced anxiogenic effects only when experienced during adulthood and cocaine induced a general anxiolytic effect. Blockade of Trkb decreased memory retention without affecting spatial learning and modified anxiety on non-stressed mice depending on their age. CONCLUSION: Our results demonstrate that the long-lasting effects of social defeat on anxiety and cognition are modulated by cocaine administration. Our results highlight that the BDNF signaling pathway could be a target to counteract the effects of cocaine on socially stressed subjects.

Differential involvement of 3', 5'-cyclic adenosine monophosphate-dependent protein kinase in regulation of Fos and tyrosine hydroxylase expression in the heart after naloxone induced morphine withdrawal.

We previously demonstrated that morphine withdrawal induced hyperactivity of the heart by the activation of noradrenergic pathways innervating the left and right ventricle, as evaluated by noradrenaline (NA) turnover and Fos expression. We investigated whether cAMP-dependent protein kinase (PKA) plays a role in this process by estimating changes in PKA immunoreactivity and the influence of inhibitor of PKA on Fos protein expression, tyrosine hydroxylase (TH) immunoreactivity levels and NA turnover in the left and right ventricle. Dependence on morphine was induced by a 7-day s.c. implantation of morphine pellets. Morphine withdrawal was precipitated on day 8 by an injection of naloxone (5 mg/kg). When opioid withdrawal was precipitated, an increase in PKA immunoreactivity and phospho-CREB (cyclic AMP response element protein) levels were observed in the heart. Moreover, morphine withdrawal induces Fos expression, an enhancement of NA turnover and an increase in the total TH levels. When the selective PKA inhibitor HA-1004 was infused, concomitantly with morphine pellets, it diminished the increase in NA turnover and the total TH levels observed in morphine-withdrawn rats. However, this inhibitor neither modifies the morphine withdrawal induced Fos expression nor the increase of nonphosphorylated TH levels. The present findings indicate that an up-regulated PKA-dependent transduction pathway might contribute to the activation of the cardiac catecholaminergic neurons in response to morphine withdrawal and suggest that Fos is not a target of PKA at heart levels.

Development of Poly(lactide-co-glicolide) Nanoparticles Incorporating Morphine Hydrochloride to Prolong its Circulation in Blood.

BACKGROUND: Formulations incorporating nanoparticles (NPs) are widely used to prolong drug release. In this regard, poly(lactide-co-glicolide) (PLGA) is often used in their preparation due to its high degree of biocompatibility and biodegradability. In the present study, morphine HCl is incorporated in PLGA-NPs and different preparation alternatives are evaluated for their effects on the properties, stability and capacity of encapsulation. METHODS: NPs were prepared by a double emulsion solvent diffusion-ammonium loading (DESD-AL) or double emulsion solvent diffusion-traditional (DESD-T) technique. NP morphology, size, zeta potential and encapsulation efficiency were investigated. In vitro studies were performed in phosphate buffer pH 7.4 at 37 ºC and deionized water at 4ºC. Adult male Swiss mice were used to study the pharmacokinetic behavior in vivo. RESULTS: Our results show that DESD-AL provides a higher level of morphine entrapment and that increasing the sonication time reduces the size but does not appreciably reduce the entrapment percentage. It was also observed that NP stability was greater when Pluronic F68 was used rather than PVA, and that in vitro assays provided better results with low concentrations of both stabilizers. Lyophilized NPs, after rehydration showed properties that were only slightly different from those of the untreated ones, with no sign of precipitation or aggregation. Finally, the obtained NPs enhanced morphine bioavailability. CONCLUSIONS: In conclusion, a useful method for encapsulating morphine in order to obtain an extended delivery period is described and its effects are compared with those of the free drug.

Repeated social defeat and the rewarding effects of cocaine in adult and adolescent mice: dopamine transcription factors, proBDNF signaling pathways, and the TrkB receptor in the mesolimbic system.

RATIONALE: Repeated social defeat (RSD) increases the rewarding effects of cocaine in adolescent and adult rodents. OBJECTIVE: The aim of the present study was to compare the long-term effects of RSD on the conditioned rewarding effects of cocaine and levels of the transcription factors Pitx3 and Nurr1 in the ventral tegmental area (VTA), the dopamine transporter (DAT), the D2 dopamine receptor (D2DR) and precursor of brain-derived neurotrophic factor (proBDNF) signaling pathways, and the tropomyosin-related kinase B (TrkB) receptor in the nucleus accumbens (NAc) in adult and adolescent mice. METHODS: Male adolescent and young adult OF1 mice were exposed to four episodes of social defeat and were conditioned 3 weeks later with 1 mg/kg of cocaine. In a second set of mice, the expressions of the abovementioned dopaminergic and proBDNF and TrkB receptor were measured in VTA and NAc, respectively. RESULTS: Adolescent mice experienced social defeats less intensely than their adult counterparts and produced lower levels of corticosterone. However, both adult and adolescent defeated mice developed conditioned place preference for the compartment associated with this low dose of cocaine. Furthermore, only adolescent defeated mice displayed diminished levels of the transcription factors Pitx3 in the VTA, without changes in the expression of DAT and D2DR in the NAc. In addition, stressed adult mice showed a decreased expression of proBDNF and the TrkB receptor, while stressed adolescent mice exhibited increased expression of latter without changes in the former. CONCLUSION: Our findings suggest that dopaminergic pathways and proBDNF signaling and TrkB receptors play different roles in social defeat-stressed mice exposed to cocaine.

Role of PKC in regulation of Fos and TH expression after naloxone induced morphine withdrawal in the heart.

We previously demonstrated that morphine withdrawal induced hyperactivity of the heart by activation of noradrenergic pathways innervating the left and right ventricle, as evaluated by noradrenaline (NA) turnover and Fos expression. The present study was designed to investigate the role of protein kinase C (PKC) in this process, by estimating whether pharmacological inhibition of PKC would attenuate morphine withdrawal induced Fos expression and changes in tyrosine hydroxylase (TH) immunoreactivity levels and NA turnover in the left and right ventricle. Dependence on morphine was induced on day 8 by an injection of naloxone. Morphine withdrawal induced Fos expression and increased TH levels and NA turnover in the right and left ventricle. Infusion of calphostin C, a selective PKC inhibitor, did not modify the morphine withdrawal-induced increase in NA turnover and TH levels. However, this inhibitor produced a reduction in the morphine withdrawal-induced Fos expression. The results of the present study provide new information on the mechanisms that underlie morphine withdrawal-induced up-regulation of Fos expression in the heart and suggest that TH is not a target of PKC during morphine withdrawal at heart levels.

Expression of heat shock protein 27 and troponin T and troponin I after naloxone-precipitated morphine withdrawal.

Heat shock protein (Hsp27) renders cardioprotection from stress situations but little is known about its role in myofilaments. In this study we have evaluated the relationship between Hsp27 and troponin response after naloxone-induced morphine withdrawal. Rats were treated with two morphine (75 mg) pellets during six days. Precipitated withdrawal was induced by naloxone on day seven. Hsp27 expression, Hsp27 phosphorylated at serine 82 (Ser82), cardiac troponin T (cTnT), cardiac troponin I (cTnI) and µ-calpain were evaluated by immunoblotting in left ventricle. Hsp, cTnT and cTnI was also evaluated by immunofluorescence procedure. Our results show that enhancement in Hsp27 expression and phosphorylation induced by naloxone-precipitated morphine withdrawal occurs with concomitant increases of cTnT and µ-calpain expression, whereas cTnI was decreased. We also observed co-localization of Hsp27 with cTnT in cardiac tissues. These findings provide new information into the possible role of Hsp27 in the protection of cTnT degradation by µ-calpain (a protease mediating proteolysis of cTnT and cTnI) after morphine withdrawal.

CP-154,526 Modifies CREB Phosphorylation and Thioredoxin-1 Expression in the Dentate Gyrus following Morphine-Induced Conditioned Place Preference.

Corticotropin-releasing factor (CRF) acts as neuro-regulator of the behavioral and emotional integration of environmental and endogenous stimuli associated with drug dependence. Thioredoxin-1 (Trx-1) is a functional protein controlling the redox status of several proteins, which is involved in addictive processes. In the present study, we have evaluated the role of CRF1 receptor (CRF1R) in the rewarding properties of morphine by using the conditioned place preference (CPP) paradigm. We also investigate the effects of the CRF1R antagonist, CP-154,526, on the morphine CPP-induced activation of CRF neurons, CREB phosphorylation and Trx expression in paraventricular nucleus (PVN) and dentate gyrus (DG) of the mice brain. CP-154,526 abolished the acquisition of morphine CPP and the increase of CRF/pCREB positive neurons in PVN. Moreover, this CRF1R antagonist prevented morphine-induced CRF-immunoreactive fibers in DG, as well as the increase in pCREB expression in both the PVN and DG. In addition, morphine exposure induced an increase in Trx-1 expression in DG without any alterations in PVN. We also observed that the majority of pCREB positive neurons in DG co-expressed Trx-1, suggesting that Trx-1 could activate CREB in the DG, a brain region involved in memory consolidation. Altogether, these results support the idea that CRF1R antagonist blocked Trx-1 expression and pCREB/Trx-1 co-localization, indicating a critical role of CRF, through CRF1R, in molecular changes involved in morphine associated behaviors.