Melatonin ameliorates injury and specific responses of ischemic striatal neurons in rats

Systematic review of melatonin in cerebral ischemia-reperfusion injury: critical role and therapeutic opportunities

Cerebral ischemia-reperfusion (I/R) injury is the predominant causes for the poor prognosis of ischemic stroke patients after reperfusion therapy. Currently, potent therapeutic interventions for cerebral I/R injury are still very limited. Melatonin, an endogenous hormone, was found to be valid in preventing I/R injury in a variety of organs. However, a systematic review covering all neuroprotective effects of melatonin in cerebral I/R injury has not been reported yet. Thus, we perform a comprehensive overview of the influence of melatonin on cerebral I/R injury by collecting all available literature exploring the latent effect of melatonin on cerebral I/R injury as well as ischemic stroke. In this systematic review, we outline the extensive scientific studies and summarize the beneficial functions of melatonin, including reducing infarct volume, decreasing brain edema, improving neurological functions and attenuating blood-brain barrier breakdown, as well as its key protective mechanisms on almost every aspect of cerebral I/R injury, including inhibiting oxidative stress, neuroinflammation, apoptosis, excessive autophagy, glutamate excitotoxicity and mitochondrial dysfunction. Subsequently, we also review the predictive and therapeutic implications of melatonin on ischemic stroke reported in clinical studies. We hope that our systematic review can provide the most comprehensive introduction of current advancements on melatonin in cerebral I/R injury and new insights into personalized diagnosis and treatment of ischemic stroke.

N,N'-Diphenyl-1,4-phenylenediamine Antioxidant's Potential Role in Enhancing the Pancreatic Antioxidant, Immunomodulatory, and Anti-Apoptotic Therapeutic Capabilities of Adipose-Derived Stem Cells in Type I Diabetic Rats

Mesenchymal stem cells (MSCs) are considered to be a promising therapeutic protocol for diabetes mellitus (DM) management. The latter is attributed to their differentiation potentiality to pancreatic β-cells, angiogenesis, and immune-modulatory capabilities by releasing various paracrine factors. Interestingly, antioxidant co-administration increased the MSCs' hypoglycemic and regenerative activities. Thus, this study aims to evaluate the therapeutic implication of type 1 DM after the co-administration of adipose tissue-derived-MSCs (AD-MSCs) and N,N'-d iphenyl-1,4-phenylenediamine (DPPD), compared to the single injection of either of them alone. In our four week long experiment, six rat groups were used as control, DPPD (250 mg/kg, i.p.), STZ-diabetic (D), D+DPPD, D+AD-MSCs (1 × 10⁶ cell/rat, i.p.), and D+AD-MSCs+DPPD groups. Within this context, a single injection of AD-MSCs or DPPD into diabetic rats showed significant pancreatic anti-inflammatory, immunomodulation, antioxidant, and anti-apoptotic capacities, superior to AD-MSCs injection. However, AD-MSCs and DPPD co-administration into diabetic rats manifested the highest hypoglycemic and pancreatic regenerative activities in managing diabetes compared to the single shot of AD-MSCs or DPPD. These results highlight the synergetic role of DPPD as an antioxidant in enhancing AD-MSCs' therapeutic applications.

Melatonin Promotes the Therapeutic Effect of Mesenchymal Stem Cells on Type 2 Diabetes Mellitus by Regulating TGF-β Pathway

Abundant evidence proves the therapeutic effect of adipose-derived mesenchymal stem cells (ADMSCs) in the treatment of diabetes mellitus. However, the problems have not been solved that viability of ADMSCs were inconsistent and the cells quickly undergo senescence after in vitro cell culture. In addition, the therapeutic effect of ADMSCs is still not satisfactory. In this study, melatonin (MLT) was added to canine ADMSC culture medium, and the treated cells were used to treat type 2 diabetes mellitus (T2DM). Our research reveals that adding MLT to ADMSC culture medium can promote the viability of ADMSCs. This effect depends on the binding of MLT and MLT receptors, which activates the transforming growth factor β (TGF-β) pathway and then changes the cell cycle of ADMSCs and improves the viability of ADMSCs. Since ADMSCs were found to be used to treat T2DM by anti-inflammatory and anti-endoplasmic reticulum (ER) stress capabilities, our data demonstrate that MLT augment several effects of ADMSCs in remission hyperglycemia, insulin resistance, and liver glycogen metabolism in T2DM patients. This suggest that ADMSCs and MLT-ADMSCs is safe and vabulable for pet clinic.

Melatonin-Pretreated Mesenchymal Stem Cells Improved Cognition in a Diabetic Murine Model

Diabetes mellitus (DM) is a multisystem endocrine disorder affecting the brain. Mesenchymal stem cells (MSCs) pretreated with Melatonin have been shown to increase the potency of MSCs. This work aimed to compare Melatonin, stem cells, and stem cells pretreated with Melatonin on the cognitive functions and markers of synaptic plasticity in an animal model of type I diabetes mellitus (TIDM). Thirty-six rats represented the animal model; six rats for isolation of MSCs and 30 rats were divided into five groups: control, TIDM, TIDM + Melatonin, TIDM + Stem cells, and TIDM + Stem ex vivo Melatonin. Functional assessment was performed with Y-maze, forced swimming test and novel object recognition. Histological and biochemical evaluation of hippocampal Neuroligin 1, Sortilin, Brain-Derived Neurotrophic Factor (BDNF), inducible nitric oxide synthase (iNOS), toll-like receptor 2 (TLR2), Tumor necrosis factor-alpha (TNF-α), and Growth Associated Protein 43 (GAP43). The TIDM group showed a significant decrease of hippocampal Neuroligin, Sortilin, and BDNF and a significant increase in iNOS, TNF-α, TLR2, and GAP43. Melatonin or stem cells groups showed improvement compared to the diabetic group but not compared to the control group. TIDM + Stem ex vivo Melatonin group showed a significant improvement, and some values were restored to normal. Ex vivo melatonin-treated stem cells had improved spatial working and object recognition memory and depression, with positive effects on glucose homeostasis, inflammatory markers levels and synaptic plasticity markers expression.

Higher Serum Melatonin Levels during the First Week of Malignant Middle Cerebral Artery Infarction in Non-Surviving Patients

Objective: The activation of different physiopathological pathways (neuroinflammation, apoptosis, and oxidation) can lead to secondary brain injury in ischemic stroke, and in animal models the administration of melatonin has reduced that secondary injury. Lower levels of serum melatonin were found at the time of admission of cerebral infarction in surviving patients than in non-surviving patients. Thus, we carried out this prospective and observational study with the aim of exploring serum melatonin levels in the first week of a malignant middle cerebral artery infarction (MMCAI) in surviving and non-surviving patients, and to explore the capacity of those levels to predict mortality. Methods: Patients with severe MMCAI, defined as computed tomography showing acute infarction in more than 50% of the territory and Glasgow Coma Scale (GCS) lower than 9, were included in the study. We measured serum melatonin concentrations at days 1, 4, and 8 of MMCAI. Mortality at 30 days was the endpoint of our study. Results: Non-surviving patients (n = 34) compared to surviving patients (n = 34) showed higher serum melatonin levels at days 1 (p < 0.001), 4 (p < 0.001), and 8 (p = 0.001) of MMCAI. Serum melatonin concentrations at days 1, 4, and 8 of MMCAI had an area under the curve (AUC) (95% confidence interval (CI)) in the prediction of mortality of 0.89 (0.80–0.96; p < 0.001), 0.81 (0.68–0.91; p < 0.001), and 0.82 (0.68–0.92; p < 0.001), respectively. Conclusions: The novel findings of our study were that serum melatonin levels in the first week of MMCAI were higher in non-surviving patients, and were able to predict mortality.

Melatonin plays critical role in mesenchymal stem cell-based regenerative medicine in vitro and in vivo

Although stem cells have emerged as promising sources for regenerative medicine, there are many potential safety hazards for their clinical application, including tumorigenicity, an availability shortage, senescence, and sensitivity to toxic environments. Mesenchymal stem cells (MSCs) have various advantages compared to other stem cells, including embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs); thus, MSCs have been intensely investigated in recent studies. However, they are placed in a harsh environment after isolation and transplantation, and the adverse microenvironment substantially reduces the viability and therapeutic effects of MSCs. Intriguingly, melatonin (MT), which is primarily secreted by the pineal organ, has been found to influence the fate of MSCs during various physiological and pathological processes. In this review, we will focus on the recent progress made regarding the influence of MT on stem cell biology and its implications for regenerative medicine. In addition, several biomaterials have been proven to significantly improve the protective effects of MT on MSCs by controlling the release of MT. Collectively, MT will be a promising agent for enhancing MSC activities and the regenerative capacity via the regulation of reactive oxygen species (ROS) generation and the release of immune factors in regenerative medicine.

Serum melatonin levels are associated with mortality in patients with malignant middle cerebral artery infarction

Objectives Lower serum melatonin levels are found in patients with ischaemic stroke compared with healthy controls. This study aimed to determine whether serum melatonin levels are associated with peroxidation status, antioxidant status, and mortality in patients with ischaemic stroke. Methods Patients with severe malignant middle cerebral artery infarction (MMCAI), defined as a Glasgow coma scale (GCS) score lower than 9, were included. Serum levels of melatonin, malondialdehyde (to assess lipid peroxidation), and total antioxidant capacity at the time of diagnosing MMCAI were determined. We chose 30-day mortality as the endpoint of the study. Results We found significantly higher serum levels of melatonin, total antioxidant capacity, and malondialdehyde in non-survivors (n = 32) than in survivors (n = 32) with MMCAI. Serum melatonin levels were associated with 30-day mortality (odds ratio = 2.205; 95% confidence interval = 1.294-3.759) after controlling for GCS score and age. We found a positive association between serum melatonin levels and total antioxidant capacity (rho = 0.36), and between serum melatonin and malondialdehyde levels (rho = 0.35). Conclusions Our study shows that serum melatonin levels are associated with peroxidation status, antioxidant status, and mortality in patients with MMCAI.

A Comparative study for striatal-direct and -indirect pathway neurons to DA depletion-induced lesion in a PD rat model

Striatal-direct and -indirect Pathway Neurons showed different vulnerability in basal ganglia disorders. Therefore, present study aimed to examine and compare characteristic changes of densities, protein and mRNA levels of soma, dendrites, and spines between striatal-direct and -indirect pathway neurons after DA depletion by using immunohistochemistry, Western blotting, real-time PCR and immunoelectron microscopy techniques. Experimental results showed that: 1) 6OHDA-induced DA depletion decreased the soma density of striatal-direct pathway neurons (SP+), but no significant changes for striatal-indirect pathway neurons (ENK+). 2) DA depletion resulted in a decline of dendrite density for both striatal-direct (D1+) and -indirect (D2+) pathway neurons, and D2+ dendritic density declined more obviously. At the ultrastructure level, the densities of D1+ and D2+ dendritic spines reduced in the 6OHDA groups compared with their control groups, but the density of D2+ dendritic spines reduced more significant than that of D1. 3) Striatal DA depletion down-regulated protein and mRNA expression levels of SP and D1, on the contrary, ENK and D2 protein and mRNA levels of indirect pathway neurons were up-regulated significantly. Present results suggested that indirect pathway neurons be more sensitive to 6OHDA-induced DA depletion.

Melatonin and Vitamin D Orchestrate Adipose Derived Stem Cell Fate by Modulating Epigenetic Regulatory Genes

Melatonin, that regulates many physiological processes including circadian rhythms, is a molecule able to promote osteoblasts maturation in vitro and to prevent bone loss in vivo, while regulating also adipocytes metabolism. In this regard, we have previously shown that melatonin in combination with vitamin D, is able to counteract the appearance of an adipogenic phenotype in adipose derived stem cells (ADSCs), cultured in an adipogenic favoring condition. In the present study, we aimed at evaluating the specific phenotype elicited by melatonin and vitamin D based medium, considering also the involvement of epigenetic regulating genes. ADSCs were cultured in a specific adipogenic conditioned media, in the presence of melatonin alone or with vitamin D. The expression of specific osteogenic related genes was evaluated at different time points, together with the histone deacetylases epigenetic regulators, HDAC1 and Sirtuins (SIRT) 1 and 2. Our results show that melatonin and vitamin D are able to modulate ADSCs commitment towards osteogenic phenotype through the upregulation of HDAC1, SIRT 1 and 2, unfolding an epigenetic regulation in stem cell differentiation and opening novel strategies for future therapeutic balancing of stem cell fate toward adipogenic or osteogenic phenotype.

Danshen-Chuanxiong-Honghua Ameliorates Cerebral Impairment and Improves Spatial Cognitive Deficits after Transient Focal Ischemia and Identification of Active Compounds

Previously, we only apply a traditional Chinese medicine (TCM) Danshen-Chuanxiong-Honghua (DCH) for cardioprotection via anti-inflammation in rats of acute myocardial infarction by occluding coronary artery. Presently, we select not only DCH but also its main absorbed compound ferulic acid (FA) for cerebra protection via similar action of mechanism above in animals of the transient middle cerebral artery occlusion (tMCAO). We investigated whether oral administration of DCH and FA could ameliorate MCAO-induced brain lesions in animals. By using liquid chromatography-tandem mass spectrometry (LC-MS/MS), we analyzed four compounds, including tanshinol, salvianolic acid B, hydroxysafflor yellow A and especially FA as the putative active components of DCH extract in the plasma, cerebrospinal fluid and injured hippocampus of rats with MCAO. In our study, it was assumed that FA played a similar neuroprotective role to DCH. We found that oral pretreatment with DCH (10 or 20 g/kg) and FA (100 mg/kg) improved neurological function and alleviated the infarct volume as well as brain edema in a dose-dependent manner. These changes were accompanied by improved ischemia-induced apoptosis and decreased the inflammatory response. Additionally, chronic treatment with DCH reversed MCAO-induced spatial cognitive deficits in a manner associated with enhanced neurogenesis and increased the expression of brain-derived neurotrophic factor in lesions of the hippocampus. These findings suggest that DCH has the ability to recover cognitive impairment and offer neuroprotection against cerebral ischemic injury via inhibiting microenvironmental inflammation and triggering of neurogenesis in the hippocampus. FA could be one of the potential active compounds.

Cortical regulation of striatal projection neurons and interneurons in a Parkinson's disease rat model

Striatal neurons can be either projection neurons or interneurons, with each type exhibiting distinct susceptibility to various types of brain damage. In this study, 6-hydroxydopamine was injected into the right medial forebrain bundle to induce dopamine depletion, and/or ibotenic acid was injected into the M1 cortex to induce motor cortex lesions. Immunohistochemistry and western blot assay showed that dopaminergic depletion results in significant loss of striatal projection neurons marked by dopamine- and cyclic adenosine monophosphate-regulated phosphoprotein, molecular weight 32 kDa, calbindin, and μ-opioid receptor, while cortical lesions reversed these pathological changes. After dopaminergic deletion, the number of neuropeptide Y-positive striatal interneurons markedly increased, which was also inhibited by cortical lesioning. No noticeable change in the number of parvalbumin-positive interneurons was found in 6-hydroxydopamine-treated rats. Striatal projection neurons and interneurons show different susceptibility to dopaminergic depletion. Further, cortical lesions inhibit striatal dysfunction and damage induced by 6-hydroxydopamine, which provides a new possibility for clinical treatment of Parkinson's disease.

The calretinin interneurons of the striatum: comparisons between rodents and primates under normal and pathological conditions

This paper reviews the major organizational features of calretinin interneurons in the dorsal striatum of rodents and primates, with some insights on the state of these neurons in Parkinson's disease and Huntington's chorea. The rat striatum harbors medium-sized calretinin-immunoreactive (CR⁺) interneurons, whereas the mouse striatum is pervaded by medium-sized CR⁺ interneurons together with numerous small and highly immunoreactive CR⁺ cells. The CR interneuronal network is even more elaborated in monkey and human striatum where, in addition to the small- and medium-sized CR⁺ interneurons, a set of large CR⁺ interneurons occurs. The majority of these giant CR⁺ interneurons, which are unique to the primate striatum, also display immunoreactivity for choline acetyltransferase (ChAT), a faithful marker of cholinergic neurons. The expression of CR and/or ChAT by the large striatal interneurons appears to be seriously compromised in Parkinson's disease and Huntington's chorea. The species differences noted above have to be considered to better understand the role of CR interneurons in striatal organization in both normal and pathological conditions.

Melatonin as a promising agent of regulating stem cell biology and its application in disease therapy

Stem cells have emerged as an important approach to repair and regenerate damaged tissues or organs and show great therapeutic potential in a variety of diseases. However, the low survival of engrafted stem cells still remains a major challenge for stem cell therapy. As a major hormone from the pineal gland, melatonin has been shown to play an important role in regulating the physiological and pathological functions of stem cells, such as promoting proliferation, migration and differentiation. Thus, melatonin combined with stem cell transplantation displayed promising application potential in neurodegenerative diseases, liver cirrhosis, wound healing, myocardial infarction, kidney ischemia injury, osteoporosis, etc. It exerts its physiological and pathological functions through its anti-oxidant, anti-inflammatory, anti-apoptosis and anti-ageing properties. Here, we summarize recent advances on exploring the biological role of melatonin in stem cells, and discuss its potential applications in stem cell-based therapy.

A Comparative Study of Three Interneuron Types in the Rat Spinal Cord

Interneurons are involved in the physiological function and the pathomechanism of the spinal cord. Present study aimed to examine and compare the characteristics of Cr+, Calb+ and Parv+ interneurons in morphology and distribution by using immunhistochemical and Western blot techniques. Results showed that 1) Cr-Calb presented a higher co-existence rate than that of Cr-Parv, and both of them were higher in the ventral horn than in the dosal horn; 2) Cr+, Calb+ and Parv+ neurons distributing zonally in the superficial dosal horn were small-sized. Parv+ neuronswere the largest, and Cr+ and Calb+ neurons were higher density among them. In the deep dorsal horn, Parv+ neurons were mainly located in nucleus thoracicus and the remaining scatteredly distributed. Cr+ neuronal size was the largest, and Calb+ neurons were the least among three interneuron types; 3) Cr+, Calb+ and Parv+ neurons of ventral horns displayed polygonal, round and fusiform, and Cr+ and Parv+ neurons were mainly distributed in the deep layer, but Calb+ neurons mainly in the superficial layer. Cr+ neurons were the largest, and distributed more in ventral horns than in dorsal horns; 4) in the dorsal horn of lumbar cords, Calb protein levels was the highest, but Parv protein level in ventral horns was the highest among the three protein types. Present results suggested that the morphological characteristics of three interneuron types imply their physiological function and pathomechanism relevance.

Methylene Blue promotes cortical neurogenesis and ameliorates behavioral deficit after photothrombotic stroke in rats

Ischemic stroke in rodents stimulates neurogenesis in the adult brain and the proliferation of newborn neurons that migrate into the penumbra zone. The present study investigated the effect of Methylene Blue (MB) on neurogenesis and functional recovery in a photothrombotic (PT) model of ischemic stroke in rats. PT stroke model was induced by photo-activation of Rose Bengal dye in cerebral blood flow by cold fiber light. Rats received intraperitoneal injection of either MB (0.5mg/kg/day) from day 1 to day 5 after stroke or an equal volume of saline solution as a control. Cell proliferative marker 5-bromodeoxyuridine (BrdU) was injected twice daily (50mg/kg) from day 2 to day 8 and animals were sacrificed on day 12 after PT induction. We report that MB significantly enhanced cell proliferation and neurogenesis, as evidenced by the increased co-localizations of BrdU/NeuN, BrdU/DCX, BrdU/MAP2 and BrdU/Ki67 in the peri-infarct zone compared with vehicle controls. MB thus effectively limited infarct volume and improved neurological deficits compared to PT control animals. The effects of MB were accompanied with an attenuated level of reactive gliosis and release of pro-inflammatory cytokines, as well as elevated levels of cytochrome c oxidase activity and ATP production in peri-infarct regions. Our study provides important information that MB has the ability to promote neurogenesis and enhance the newborn-neurons' survival in ischemic brain repair by inhibiting microenvironmental inflammation and increasing mitochondrial function.

Dihydromyricetin Ameliorates 3NP-induced Behavioral Deficits and Striatal Injury in Rats

Oxidative stress is closely involved in neurodegenerative diseases. The present study aimed to examine the effect of anti-oxidant DHM (dihydromyricetin) on 3NP (3-nitropropionic acid) -induced behavioral deficits of experimental rats and striatal histopathological injury by using behavioral, imaging, biochemistry, histochemistry and molecular biology technologies. The experimental results showed that both motor dysfunctions and learning and memory impairments induced by 3NP were significantly reduced after DHM treatment. 3NP-induced striatal metabolic abnormality was also remarkably improved by DHM treatment, showed as the increased glucose metabolism in PET/CT scan, decreased MDA (malondialdehyde) and increased SOD (superoxide dismutase) activity in enzyme histochemical staining. In addition, the cell apoptosis was evidently detected in the striatum of the 3NP group, while in the 3NP + DHM group, the number of apoptotic cells was remarkably reduced. 3NP treatment obviously induced down-regulation of Bcl-2, and up-regulations of Bax and Cleaved Caspase-3, while these changes were significantly reversed by DHM treatment. The present results suggested that DHM showed its protective effect by anti-oxidant and anti-apoptosis mechanisms.

The number of striatal cholinergic interneurons expressing calretinin is increased in parkinsonian monkeys

The most abundant interneurons in the primate striatum are those expressing the calcium-binding protein calretinin (CR). The present immunohistochemical study provides detailed assessments of their morphological traits, number, and topographical distribution in normal monkeys (Macaca fascicularis) and in monkeys rendered parkinsonian (PD) by MPTP intoxication. In primates, the CR+ striatal interneurons comprise small (8-12μm), medium (12-20μm) and large-sized (20-45μm) neurons, each with distinctive morphologies. The small CR+ neurons were 2-3 times more abundant than the medium-sized CR+ neurons, which were 20-40 times more numerous than the large CR+ neurons. In normal and PD monkeys, the density of small and medium-sized CR+ neurons was twice as high in the caudate nucleus than in the putamen, whereas the inverse occurred for the large CR+ neurons. Double immunostaining experiments revealed that only the large-sized CR+ neurons expressed choline acetyltransferase (ChAT). The number of large CR+ neurons was found to increase markedly (4-12 times) along the entire anteroposterior extent of both the caudate nucleus and putamen of PD monkeys compared to controls. Comparison of the number of large CR-/ChAT+ and CR+/ChAT+ neurons together with experiments involving the use of bromo-deoxyuridine (BrdU) as a marker of newly generated cells showed that it is the expression of CR by the large ChAT+ striatal interneurons, and not their absolute number, that is increased in the dopamine-depleted striatum. These findings reveal the modulatory role of dopamine in the phenotypic expression of the large cholinergic striatal neurons, which are known to play a crucial role in PD pathophysiology.

Characteristic Changes of Astrocyte and Microglia in Rat Striatum Induced by 3-NP and MCAO

Our previous studies had confirmed that both 3-NP and MCAO induced the behavioral defect as well as striatal neuronal injury and loss in experimental rats. This study aimed to examine different response forms of striatal astrocyte and microglia in 3-NP and MCAO rat models. The present results showed that the immunoreaction for GFAP was extremely weak in the lesioned core of striatum, but in the transition zone of 3-NP model and the penumbra zone of MCAO model, GFAP+ cells showed strong hypertrophic and proliferative changes. Statistical analysis for the number, size and integral optical density (IOD) of GFAP+ cells showed significant differences when compared with their controls and compared between the core and the transition zone or the penumbra zone, respectively, but no differences between the 3-NP and MCAO groups. However, Iba-1+ cells showed obvious hypertrophy and proliferation in the injured striatum in the 3-NP and the MCAO models, especially in the transition zone of 3-NP model and the penumbra zone of MCAO model. These Iba-1+ cells displayed two characteristic forms as branching cells with thick processes and amoeboid cells with thin processes. Statistical analysis showed that the number, size and IOD of Iba-1+ cells were significantly increased in the cores and the transition zone of 3-NP group and the penumbra zone of MCAO group than that of the controls, and the immune response of Iba-1 was stronger in the MCAO group than in the 3-NP group. The present results suggested that characteristic responses of astrocyte and microglia in the 3-NP and the MCAO models display their different effects on the pathological process of brain injury.

Melatonin counteracts changes in hypothalamic gene expression of signals regulating feeding behavior in high-fat fed rats

BACKGROUND

Previous studies indicate that the administration of melatonin caused body weight and abdominal visceral fat reductions in rodent models of hyperadiposity. The objective of the present study performed in high-fat fed rats was to evaluate the activity of melatonin on gene expression of some medial basal hypothalamus (MBH) signals involved in feeding behavior regulation, including neuropeptide Y (NPY), proopiomelanocortin (POMC), prolactin-releasing peptide (PrRP), leptin- and insulin-receptors (R) and insulin-R substrate (IRS)-1 and -2. Blood levels of leptin and adiponectin were also measured.

METHODS

Adult Wistar male rats were divided into four groups (n=16 per group): (i) control diet (3% fat); (ii) high-fat (35%) diet; (iii) high-fat diet+melatonin; (iv) control diet+melatonin. Rats had free access to high-fat or control chow and one of the following drinking solutions: (a) tap water; (b) 25 μg/mL of melatonin.

RESULTS

After 10 weeks, the high-fat fed rats showed augmented MBH mRNA levels of NPY, leptin-R, PrRP, insulin-R, IRS-1 and IRS-2. The concomitant administration of melatonin counteracted this increase. Feeding of rats with a high-fat diet augmented expression of the MBH POMC gene through an effect insensitive to melatonin treatment. The augmented levels of circulating leptin and adiponectin seen in high-fat fed rats were counteracted by melatonin as was the augmented body weight: melatonin significantly attenuated a body weight increase in high-fat fed rats without affecting chow or water consumption. Melatonin augmented plasma leptin and adiponectin in control rats.

CONCLUSIONS

The results indicate that an effect on gene expression of feeding behavior signals at the central nervous system (CNS) may complement a peripheral rise of the energy expenditure produced by melatonin to decrease body weight in high-fat fed rats.

The effects of unilateral 6-OHDA lesion in medial forebrain bundle on the motor, cognitive dysfunctions and vulnerability of different striatal interneuron types in rats

In this study, the motor deficit, cognition impairment and the vulnerability of different striatal interneurons to the 6-hydroxydopamine (6-OHDA)-induced excitotoxicity in unilateral medial forebrain bundle (MFB) lesion rats were analyzed by employing behavioral test, immunohistochemistry and Western blot methods. The apomorphine-induced rotation after MFB lesion was used as a valid criterion of motor deficit. The 6-OHDA damaged rats had limb rigidity with longer hang time compared to the controls in the grip strength test. Cognitive and mnemonic deficits of rats with unilateral MFB lesion were observed by the water maze task. The MFB lesion resulted in a significant loss of tyrosine hydroxylase (TH)+ cells in the contralateral striatum or substantia nigra. After dopaminergic depletion, the numbers of calretinin (Cr)+ and choline acetyltransferase (ChAT)+ interneurons were notably reduced while these of neuropeptide Y (NPY)+ were markedly increased in the striatum. No noticeable change in the number of parvalbumin (Parv)+ interneurons was found in 6-OHDA rats. In addition, the fiber densities for each individual interneuron were increased after 6-OHDA treatment, especially for the fiber densities of Parv+ and Cr+ interneurons. The Western blot analysis further confirmed the results described above. In conclusion, the MFB lesion model is suitable to mimic Parkinson's disease (PD), and our results are helpful for further understanding the underlying mechanism and the specific functions of various striatal interneurons in the pathological process of PD.