ß2-Integrins Regulate Microglial Responses and the Functional Outcome of Hemorrhagic Stroke In Vivo.

Stroke is one of the leading causes of death and long-term disabilities worldwide. In addition to interruption of blood flow, inflammation is widely recognized as an important factor mediating tissue destruction in stroke. Depending on their phenotype, microglia, the main leukocytes in the CNS, are capable of either causing further tissue damage or promoting brain restoration after stroke. ß2-integrins are cell adhesion molecules that are constitutively expressed on microglia. The function of ß2-integrins has been investigated extensively in animal models of ischemic stroke, but their role in hemorrhagic stroke is currently poorly understood. We show in this study that dysfunction of ß2-integrins is associated with improved functional outcome and decreased inflammatory cytokine expression in the brain in a mouse model of hemorrhagic stroke. Furthermore, ß2-integrins affect microglial phenotype and cytokine responses in vivo. Therefore, our findings suggest that targeting ß2-integrins in hemorrhagic stroke may be beneficial.

Pharmacological Regulation of Endoplasmic Reticulum Structure and Calcium Dynamics: Importance for Neurodegenerative Diseases.

The endoplasmic reticulum (ER) is the largest organelle of the cell, composed of a continuous network of sheets and tubules, and is involved in protein, calcium (Ca2+), and lipid homeostasis. In neurons, the ER extends throughout the cell, both somal and axodendritic compartments, and is highly important for neuronal functions. A third of the proteome of a cell, secreted and membrane-bound proteins, are processed within the ER lumen and most of these proteins are vital for neuronal activity. The brain itself is high in lipid content, and many structural lipids are produced, in part, by the ER. Cholesterol and steroid synthesis are strictly regulated in the ER of the blood-brain barrier protected brain cells. The high Ca2+ level in the ER lumen and low cytosolic concentration is needed for Ca2+-based intracellular signaling, for synaptic signaling and Ca2+ waves, and for preparing proteins for correct folding in the presence of high Ca2+ concentrations to cope with the high concentrations of extracellular milieu. Particularly, ER Ca2+ is controlled in axodendritic areas for proper neurito- and synaptogenesis and synaptic plasticity and remodeling. In this review, we cover the physiologic functions of the neuronal ER and discuss it in context of common neurodegenerative diseases, focusing on pharmacological regulation of ER Ca2+ Furthermore, we postulate that heterogeneity of the ER, its protein folding capacity, and ensuring Ca2+ regulation are crucial factors for the aging and selective vulnerability of neurons in various neurodegenerative diseases. SIGNIFICANCE STATEMENT: Endoplasmic reticulum (ER) Ca2+ regulators are promising therapeutic targets for degenerative diseases for which efficacious drug therapies do not exist. The use of pharmacological probes targeting maintenance and restoration of ER Ca2+ can provide restoration of protein homeostasis (e.g., folding of complex plasma membrane signaling receptors) and slow down the degeneration process of neurons.

Protective mechanisms by glial cell line-derived neurotrophic factor and cerebral dopamine neurotrophic factor against the α-synuclein accumulation in Parkinson's disease.

Synucleinopathies constitute a disease family named after alpha-synuclein protein, which is a significant component of the intracellular inclusions called Lewy bodies. Accompanying the progressive neurodegeneration, Lewy bodies and neurites are the main histopathologies of synucleinopathies. The complicated role of alpha-synuclein in the disease pathology makes it an attractive therapeutic target for disease-modifying treatments. GDNF is one of the most potent neurotrophic factors for dopamine neurons, whereas CDNF is protective and neurorestorative with entirely different mechanisms of action. Both have been in the clinical trials for the most common synucleinopathy, Parkinson's disease. With the AAV-GDNF clinical trials ongoing and the CDNF trial being finalized, their effects on abnormal alpha-synuclein accumulation are of great interest. Previous animal studies with an alpha-synuclein overexpression model have shown that GDNF was ineffective against alpha-synuclein accumulation. However, a recent study with cell culture and animal models of alpha-synuclein fibril inoculation has demonstrated the opposite by revealing that the GDNF/RET signaling cascade is required for the protective effect of GDNF on alpha-synuclein aggregation. CDNF, an ER resident protein, was shown to bind alpha-synuclein directly. CDNF reduced the uptake of alpha-synuclein fibrils by the neurons and alleviated the behavioral deficits induced by fibrils injected into the mouse brain. Thus, GDNF and CDNF can modulate different symptoms and pathologies of Parkinson's disease, and perhaps, similarly for other synucleinopathies. Their unique mechanisms for preventing alpha-synuclein-related pathology should be studied more carefully to develop disease-modifying therapies.

Cross-talk between bioactive lipid mediators and the unfolded protein response in ischemic stroke.

Ischemic cerebral stroke is a severe medical condition that affects about 15 million people every year and is the second leading cause of death and disability globally. Ischemic stroke results in neuronal cell death and neurological impairment. Current therapies may not adequately address the deleterious metabolic changes and may increase neurological damage. Oxygen and nutrient depletion along with the tissue damage result in endoplasmic reticulum (ER) stress, including the Unfolded Protein Response (UPR), and neuroinflammation in the affected area and cause cell death in the lesion core. The spatio-temporal production of lipid mediators, either pro-inflammatory or pro-resolving, decides the course and outcome of stroke. The modulation of the UPR as well as the resolution of inflammation promotes post-stroke cellular viability and neuroprotection. However, studies about the interplay between the UPR and bioactive lipid mediators remain elusive and this review gives insights about the crosstalk between lipid mediators and the UPR in ischemic stroke. Overall, the treatment of ischemic stroke is often inadequate due to lack of effective drugs, thus, this review will provide novel therapeutical strategies that could promote the functional recovery from ischemic stroke.

α-Synuclein binding activity of the plant growth promoter asterubine.

Preventing the aggregation of certain amyloid proteins has the potential to slow down the progression of diseases like Alzheimer's, Parkinson's, and type 2 diabetes mellitus. During a high-throughput screen of 300 Australian marine invertebrate extracts, the extract of the marine sponge Thorectandra sp. 4408 displayed binding activity to the Parkinson's disease-associated protein, α-synuclein. Isolation of the active component led to its identification as the known plant growth promoter asterubine (1). This molecule shares distinct structural similarities with potent amyloid beta aggregation inhibitors tramiprosate (homotaurine) and ALZ-801. Herein we report the isolation, NMR data acquired in DMSO and α-synuclein binding activity of asterubine (1).

Cerebral dopamine neurotrophic factor reduces α-synuclein aggregation and propagation and alleviates behavioral alterations in vivo.

A molecular hallmark in Parkinson's disease (PD) pathogenesis are α-synuclein aggregates. Cerebral dopamine neurotrophic factor (CDNF) is an atypical growth factor that is mostly resident in the endoplasmic reticulum but exerts its effects both intracellularly and extracellularly. One of the beneficial effects of CDNF can be protecting neurons from the toxic effects of α-synuclein. Here, we investigated the effects of CDNF on α-synuclein aggregation in vitro and in vivo. We found that CDNF directly interacts with α-synuclein with a KD = 23 ± 6 nM and reduces its auto-association. Using nuclear magnetic resonance (NMR) spectroscopy, we identified interaction sites on the CDNF protein. Remarkably, CDNF reduces the neuronal internalization of α-synuclein fibrils and induces the formation of insoluble phosphorylated α-synuclein inclusions. Intra-striatal CDNF administration alleviates motor deficits in rodents challenged with α-synuclein fibrils, though it did not reduce the number of phosphorylated α-synuclein inclusions in the substantia nigra. CDNF's beneficial effects on rodent behavior appear not to be related to the number of inclusions formed in the current context, and further study of its effects on the aggregation mechanism in vivo are needed. Nonetheless, the interaction of CDNF with α-synuclein, modifying its aggregation, spreading, and associated behavioral alterations, provides novel insights into the potential of CDNF as a therapeutic strategy in PD and other synucleinopathies.

Female C57BL/6J Mice Show Alcohol-Seeking Behaviour after Withdrawal from Prolonged Alcohol Consumption in the Social Environment.

AIMS: Recently we developed a model to study alcohol-seeking behaviour after withdrawal in a social context in female mice. The model raised several questions that we were eager to address to improve methodology. METHODS: In our model, female mice were group-housed in automated cages with three conditioned (CS+) corners and water in both sides of one separate non-conditioned corner. Water was available with opened doors at all the time of training. We established conditioning by pairing alcohol drinking with light cues. Here, we introduced prolonged access to increasing concentrations of alcohol instead of intermittent access. To study motivation to drink alcohol, we carried out the extinction tests on withdrawal days 1 (WD1) and 10 (WD10). During tests, the light cues were present in conditioned corners, but there was no liquid in the bottles. RESULTS: We found that the number of visits and nosepokes in the CS+ corner in the alcohol group was much higher than in the water group. Also, during training, the consumption of alcohol was increasing. In the extinction tests, we found that the number of nosepokes in the CS+ corner increased in the alcohol group on both WD1 and WD10. CONCLUSIONS: Our study supports that alcohol-seeking behaviour after withdrawal can be modelled and studied in group-housed animals and environments without social isolation.

The overexpression of GDNF in nucleus accumbens suppresses alcohol-seeking behavior in group-housed C57Bl/6J female mice.

BACKGROUND: Craving for alcohol, in other words powerful desire to drink after withdrawal, is an important contributor to the development and maintenance of alcoholism. Here, we studied the role of GDNF (glial cell line-derived neurotrophic factor) and BDNF (brain-derived neurotrophic factor) on alcohol-seeking behavior in group-housed female mice. METHODS: We modeled alcohol-seeking behavior in C57Bl/6J female mice. The behavioral experiments in group-housed female mice were performed in an automated IntelliCage system. We conducted RT-qPCR analysis of Gdnf, Bdnf, Manf and Cdnf expression in different areas of the female mouse brain after alcohol drinking conditioning. We injected an adeno-associated virus (AAV) vector expressing human GDNF or BDNF in mouse nucleus accumbens (NAc) after ten days of alcohol drinking conditioning and assessed alcohol-seeking behavior. Behavioral data were analyzed by two-way repeated-measures ANOVA, and statistically significant effects were followed by Bonferroni's post hoc test. The student's t-test was used to analyze qPCR data. RESULTS: The RT-qPCR data showed that Gdnf mRNA level in NAc was more than four times higher (p < 0.0001) in the mice from the sweetened alcohol group compared to the water group. Our data showed a more than a two-fold decrease in Manf mRNA (p = 0.04) and Cdnf mRNA (p = 0.02) levels in the hippocampus and Manf mRNA in the VTA (p = 0.04) after alcohol consumption. Two-fold endogenous overexpression of Gdnf mRNA and lack of CDNF did not affect alcohol-seeking behavior. The AVV-GDNF overexpression in nucleus accumbens suppressed alcohol-seeking behavior while overexpression of BDNF did not. CONCLUSIONS: The effect of increased endogenous Gdnf mRNA level in female mice upon alcohol drinking has remained unknown. Our data suggest that an increase in endogenous GDNF expression upon alcohol drinking occurs in response to the activation of another mesolimbic reward pathway participant.

Cerebral dopamine neurotrophic factor-deficiency leads to degeneration of enteric neurons and altered brain dopamine neuronal function in mice.

Cerebral dopamine neurotrophic factor (CDNF) is neuroprotective for nigrostriatal dopamine neurons and restores dopaminergic function in animal models of Parkinson's disease (PD). To understand the role of CDNF in mammals, we generated CDNF knockout mice (Cdnf-/-), which are viable, fertile, and have a normal life-span. Surprisingly, an age-dependent loss of enteric neurons occurs selectively in the submucosal but not in the myenteric plexus. This neuronal loss is a consequence not of increased apoptosis but of neurodegeneration and autophagy. Quantitatively, the neurodegeneration and autophagy found in the submucosal plexus in duodenum, ileum and colon of the Cdnf-/- mouse are much greater than in those of Cdnf+/+ mice. The selective vulnerability of submucosal neurons to the absence of CDNF is reminiscent of the tendency of pathological abnormalities to occur in the submucosal plexus in biopsies of patients with PD. In contrast, the number of substantia nigra dopamine neurons and dopamine and its metabolite concentrations in the striatum are unaltered in Cdnf-/- mice; however, there is an age-dependent deficit in the function of the dopamine system in Cdnf-/- male mice analyzed. This is observed as D-amphetamine-induced hyperactivity, aberrant dopamine transporter function, and as increased D-amphetamine-induced dopamine release demonstrating that dopaminergic axon terminal function in the striatum of the Cdnf-/- mouse brain is altered. The deficiencies of Cdnf-/- mice, therefore, are reminiscent of those seen in early stages of Parkinson's disease.

GDNF/RET Signaling Pathway Activation Eliminates Lewy Body Pathology in Midbrain Dopamine Neurons.

BACKGROUND: Parkinson's disease (PD) is associated with proteostasis disturbances and accumulation of misfolded α-synuclein (α-syn), a cytosolic protein present in high concentrations at pre-synaptic neuronal terminals. It is a primary constituent of intracellular protein aggregates known as Lewy neurites or Lewy bodies. Progression of Lewy pathology caused by the prion-like self-templating properties of misfolded α-syn is a characteristic feature in the brains of PD patients. Glial cell line-derived neurotrophic factor (GDNF) promotes survival of mature dopamine (DA) neurons in vitro and in vivo. However, the data on its effect on Lewy pathology is controversial. OBJECTIVES: We studied the effects of GDNF on misfolded α-syn accumulation in DA neurons. METHODS: Lewy pathology progression was modeled by the application of α-syn preformed fibrils in cultured DA neurons and in the adult mice. RESULTS: We discovered that GDNF prevented accumulation of misfolded α-syn in DA neurons in culture and in vivo. These effects were abolished by deletion of receptor tyrosine kinase rearranged during transfection (RET) or by inhibitors of corresponding signaling pathway. Expression of constitutively active RET protected DA neurons from fibril-induced α-syn accumulation. CONCLUSIONS: For the first time, we have shown the neurotrophic factor-mediated protection against the misfolded α-syn propagation in DA neurons, uncovered underlying receptors, and investigated the involved signaling pathways. These results demonstrate that activation of GDNF/RET signaling can be an effective therapeutic approach to prevent Lewy pathology spread at early stages of PD. © 2020 International Parkinson and Movement Disorder Society.

Differentiation and molecular heterogeneity of inhibitory and excitatory neurons associated with midbrain dopaminergic nuclei.

Local inhibitory GABAergic and excitatory glutamatergic neurons are important for midbrain dopaminergic and hindbrain serotonergic pathways controlling motivation, mood, and voluntary movements. Such neurons reside both within the dopaminergic nuclei, and in adjacent brain structures, including the rostromedial and laterodorsal tegmental nuclei. Compared with the monoaminergic neurons, the development, heterogeneity, and molecular characteristics of these regulatory neurons are poorly understood. We show here that different GABAergic and glutamatergic subgroups associated with the monoaminergic nuclei express specific transcription factors. These neurons share common origins in the ventrolateral rhombomere 1, where the postmitotic selector genes Tal1, Gata2 and Gata3 control the balance between the generation of inhibitory and excitatory neurons. In the absence of Tal1, or both Gata2 and Gata3, the GABAergic precursors adopt glutamatergic fates and populate the glutamatergic nuclei in excessive numbers. Together, our results uncover developmental regulatory mechanisms, molecular characteristics, and heterogeneity of central regulators of monoaminergic circuits.

Downregulation of tyrosine hydroxylase phenotype after AAV injection above substantia nigra: Caution in experimental models of Parkinson's disease.

Adeno-associated virus (AAV) vector-mediated delivery of human α-synuclein (α-syn) gene in rat substantia nigra (SN) results in increased expression of α-syn protein in the SN and striatum which can progressively degenerate dopaminergic neurons. Therefore, this model is thought to recapitulate the neurodegeneration in Parkinson's disease. Here, using AAV to deliver α-syn above the SN in male and female rats resulted in clear expression of human α-syn in the SN and striatum. The protein was associated with moderate behavioral deficits and some loss of tyrosine hydroxylase (TH) in the nigrostriatal areas. However, the immunohistochemistry results were highly variable and showed little to no correlation with behavior and the amount of α-syn present. Expression of green fluorescent protein (GFP) was used as a control to monitor gene delivery and expression efficacy. AAV-GFP resulted in a similar or greater TH loss compared to AAV-α-syn and therefore an additional vector that does not express a protein was tested. Vectors with double-floxed inverse open reading frame (DIO ORF) encoding fluorescent proteins that generate RNA that is not translated also resulted in TH downregulation in the SN but showed no significant behavioral deficits. These results demonstrate that although expression of wild-type human α-syn can cause neurodegeneration, the variability and lack of correlation with outcome measures are drawbacks with the model. Furthermore, design and control selection should be considered carefully because of conflicting conclusions due to AAV downregulation of TH, and we recommend caution with having highly regulated TH as the only marker for the dopamine system.

MANF Promotes Differentiation and Migration of Neural Progenitor Cells with Potential Neural Regenerative Effects in Stroke.

Cerebral ischemia activates endogenous reparative processes, such as increased proliferation of neural stem cells (NSCs) in the subventricular zone (SVZ) and migration of neural progenitor cells (NPCs) toward the ischemic area. However, this reparative process is limited because most of the NPCs die shortly after injury or are unable to arrive at the infarct boundary. In this study, we demonstrate for the first time that endogenous mesencephalic astrocyte-derived neurotrophic factor (MANF) protects NSCs against oxygen-glucose-deprivation-induced injury and has a crucial role in regulating NPC migration. In NSC cultures, MANF protein administration did not affect growth of cells but triggered neuronal and glial differentiation, followed by activation of STAT3. In SVZ explants, MANF overexpression facilitated cell migration and activated the STAT3 and ERK1/2 pathway. Using a rat model of cortical stroke, intracerebroventricular injections of MANF did not affect cell proliferation in the SVZ, but promoted migration of doublecortin (DCX)+ cells toward the corpus callosum and infarct boundary on day 14 post-stroke. Long-term infusion of MANF into the peri-infarct zone increased the recruitment of DCX+ cells in the infarct area. In conclusion, our data demonstrate a neuroregenerative activity of MANF that facilitates differentiation and migration of NPCs, thereby increasing recruitment of neuroblasts in stroke cortex.

Neuroprotective and reparative effects of endoplasmic reticulum luminal proteins - mesencephalic astrocyte-derived neurotrophic factor and cerebral dopamine neurotrophic factor.

Cerebral dopamine neurotrophic factor (CDNF) and mesencephalic astrocyte-derived neurotrophic factor (MANF) are proteins that have received increasing attention in the last decades. Although they are called neurotrophic factors they are drastically different from neurotrophic factors in their expression and physiological actions. They are located in the lumen of the endoplasmic reticulum (ER) and their basal secretion from neurons is very low. However their secretion is stimulated upon ER calcium depletion by chemical probes such as thapsigargin, a sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) pump inhibitor. Exogenous MANF and CDNF possess therapeutic properties in several neurological disease models, including Parkinson disease and stroke. Endogenous MANF expression has been shown to be neuroprotective, as well as administration of either CDNF or MANF into the extracellular space. In this review, we focus on their therapeutic effects, regulation of expression and secretion, comparison of their mechanisms of action, and their application to the brain parenchyma as recombinant proteins.

Implementation of deep neural networks to count dopamine neurons in substantia nigra.

Unbiased estimates of neuron numbers within substantia nigra are crucial for experimental Parkinson's disease models and gene-function studies. Unbiased stereological counting techniques with optical fractionation are successfully implemented, but are extremely laborious and time-consuming. The development of neural networks and deep learning has opened a new way to teach computers to count neurons. Implementation of a programming paradigm enables a computer to learn from the data and development of an automated cell counting method. The advantages of computerized counting are reproducibility, elimination of human error and fast high-capacity analysis. We implemented whole-slide digital imaging and deep convolutional neural networks (CNN) to count substantia nigra dopamine neurons. We compared the results of the developed method against independent manual counting by human observers and validated the CNN algorithm against previously published data in rats and mice, where tyrosine hydroxylase (TH)-immunoreactive neurons were counted using unbiased stereology. The developed CNN algorithm and fully cloud-embedded Aiforia™ platform provide robust and fast analysis of dopamine neurons in rat and mouse substantia nigra.

Update of neurotrophic factors in neurobiology of addiction and future directions.

Drug addiction is a chronic brain disease and drugs of abuse cause long lasting neuroadaptations. Addiction is characterized by the loss of control over drug use despite harmful consequences, and high rates of relapse even after long periods of abstinence. Neurotrophic factors (NTFs) are well known for their actions on neuronal survival in the peripheral nervous system. Moreover, NTFs have been shown to be involved in synaptic plasticity in the brain. Brain-derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF) are two of the most studied NTFs and both of them have been reported to increase craving when administered into the mesocorticolimbic dopaminergic system after drug self-administration. Here we review recent data on BDNF and GDNF functions in addiction-related behavior and discuss them in relation to previous findings. Finally, we give an insight into how new technologies could aid in further elucidating the role of these factors in drug addiction.

Nigral injection of a proteasomal inhibitor, lactacystin, induces widespread glial cell activation and shows various phenotypes of Parkinson's disease in young and adult mouse.

Proteinaceous inclusions, called Lewy bodies, are used as a pathological hallmark for Parkinson's disease (PD). Lewy bodies contain insoluble α-synuclein (aSyn) and many other ubiquitinated proteins, suggesting a role for protein degradation system failure in the PD pathogenesis. Indeed, proteasomal dysfunction has been linked to PD but commonly used in vivo toxin models, such as 6-OHDA or MPTP, do not have a significant effect on the proteasomal system or protein aggregation. Therefore, we wanted to study the characteristics of a proteasomal inhibitor, lactacystin, as a PD model on young and adult mice. To study this, we performed stereotactic microinjection of lactacystin above the substantia nigra pars compacta in young (2 month old) and adult (12-14 month old) C57Bl/6 mice. Motor behavior was measured by locomotor activity and cylinder tests, and the markers of neuroinflammation, aSyn, and dopaminergic system were assessed by immunohistochemistry and HPLC. We found that lactacystin induced a Parkinson's disease-like motor phenotype 5-7 days after injection in young and adult mice, and this was associated with widespread neuroinflammation based on glial cell markers, aSyn accumulation in substantia nigra, striatal dopamine decrease, and loss of dopaminergic cell bodies in the substantia nigra and terminals in the striatum. When comparing young and adult mice, adult mice were more sensitive for dopaminergic degeneration after lactacystin injection that further supports the use of adult mice instead of young when modeling neurodegeneration. Our data showed that lactacystin is useful in modeling various aspects of Parkinson's disease, and taken together, our findings emphasize the role of a protein degradation deficit in Parkinson's disease pathology, and support the use of proteasomal inhibitors as Parkinson's disease models.

Developing therapeutically more efficient Neurturin variants for treatment of Parkinson's disease.

In Parkinson's disease midbrain dopaminergic neurons degenerate and die. Oral medications and deep brain stimulation can relieve the initial symptoms, but the disease continues to progress. Growth factors that might support the survival, enhance the activity, or even regenerate degenerating dopamine neurons have been tried with mixed results in patients. As growth factors do not pass the blood-brain barrier, they have to be delivered intracranially. Therefore their efficient diffusion in brain tissue is of crucial importance. To improve the diffusion of the growth factor neurturin (NRTN), we modified its capacity to attach to heparan sulfates in the extracellular matrix. We present four new, biologically fully active variants with reduced heparin binding. Two of these variants are more stable than WT NRTN in vitro and diffuse better in rat brains. We also show that one of the NRTN variants diffuses better than its close homolog GDNF in monkey brains. The variant with the highest stability and widest diffusion regenerates dopamine fibers and improves the conditions of rats in a 6-hydroxydopamine model of Parkinson's disease more potently than GDNF, which previously showed modest efficacy in clinical trials. The new NRTN variants may help solve the major problem of inadequate distribution of NRTN in human brain tissue.

Characterization of a new low-dose 6-hydroxydopamine model of Parkinson's disease in rat.

Intrastriatal administration of 6-hydroxydopamine (6-OHDA) induces partial degeneration of the nigrostriatal pathway, mimicking the pathology of Parkinson's disease (PD). Setting up the partial lesion model can be challenging because a number of experimental settings can be altered. This study compares seven experimental settings in a single study on d-amphetamine-induced rotations, tyrosine hydroxylase (TH)-positive neurites in the striatum, dopamine transporter (DAT)-positive neurites in the striatum, and TH-positive cells in the substantia nigra pars compacta (SNpc) in rats. Moreover, we validate a new algorithm for estimating the number of TH-positive cells. We show that the behavior and immunoreactivity vary greatly depending on the injection settings, and we categorize the lesions as progressive, stable, or regressive based on d-amphetamine-induced rotations. The rotation behavior correlated with the degree of the lesion, analyzed by immunohistochemistry; the largest lesions were in the progressive group, and the smallest lesions were in the regressive group. We establish a new low-dose partial 6-OHDA lesion model in which a total of 6 µg was distributed evenly to three sites in the striatum at a 10° angle. The administration of low-dose 6-OHDA produced stable and reliable rotation behavior and induced partial loss of striatal TH-positive and DAT-positive neurites and TH-positive cells in the SNpc. This model is highly suitable for neurorestoration studies in the search for new therapies for PD, and the new algorithm increases the efficacy for estimating the number of dopamine neurons. This study can be extremely useful for laboratories setting up the partial 6-OHDA model.

Accumbal µ-Opioid Receptors Modulate Ethanol Intake in Alcohol-Preferring Alko Alcohol Rats.

BACKGROUND: The nucleus accumbens shell is a key brain area mediating the reinforcing effects of ethanol (EtOH). Previously, it has been shown that the density of µ-opioid receptors in the nucleus accumbens shell is higher in alcohol-preferring Alko Alcohol (AA) rats than in alcohol-avoiding Alko Non-Alcohol rats. In addition, EtOH releases opioid peptides in the nucleus accumbens and opioid receptor antagonists are able to modify EtOH intake, all suggesting an opioidergic mechanism in the control of EtOH consumption. As the exact mechanisms of opioidergic involvement remains to be elucidated, the aim of this study was to clarify the role of accumbal µ- and κ-opioid receptors in controlling EtOH intake in alcohol-preferring AA rats. METHODS: Microinfusions of the µ-opioid receptor antagonist CTOP (0.3 and 1 µg/site), µ-opioid receptor agonist DAMGO (0.03 and 0.1 µg/site), nonselective opioid receptor agonist morphine (30 µg/site), and κ-opioid receptor agonist U50488H (0.3 and 1 µg/site) were administered via bilateral guide cannulas into the nucleus accumbens shell of AA rats that voluntarily consumed 10% EtOH solution in an intermittent, time-restricted (90-minute) 2-bottle choice access paradigm. RESULTS: CTOP (1 µg/site) significantly increased EtOH intake. Conversely, DAMGO resulted in a decreasing trend in EtOH intake. Neither morphine nor U50488H had any effect on EtOH intake in the used paradigm. CONCLUSIONS: The results provide further evidence for the role of accumbens shell µ-opioid receptors but not κ-opioid receptors in mediating reinforcing effects of EtOH and in regulating EtOH consumption. The results also provide support for views suggesting that the nucleus accumbens shell has a major role in mediating EtOH reward.