Intermittent l-DOPA treatment differentially alters synaptotagmin 4 and 7 gene expression in the striatum of hemiparkinsonian rats

Modulation by Estradiol of L-Dopa-Induced Dyskinesia in a Rat Model of Post-Menopausal Hemiparkinsonism

Treatment with levodopa (L-dopa) in Parkinson’s disease (PD) leads to involuntary movements termed L-dopa-induced dyskinesia (LID). There are contradictory data about the influence of hormone therapy in female PD patients with LID and of 17-β-estradiol (E2) on animal correlates of LID-abnormal involuntary movements (AIMs). Our aim was to characterize the influence of E2 on motor impairment and AIMs in ovariectomized 6-hydroxydopamine (6-OHDA) rat model of PD. Half of the rats received empty and the other half implants filled with E2. Following the 6-OHDA surgery, the rats received daily treatment with either L-dopa or saline for 16 days. They were assessed for AIMs, contralateral rotations, and FAS. In the L-dopa-treated rats, E2 intensified and prolonged AIMs and contralateral rotations. On the other hand, it had no effect on motor impairment. Postmortem tyrosine hydroxylase immunostaining revealed an almost complete unilateral lesion of nigrostriatal dopaminergic neurons. E2 partially prevented the upregulation of striatal ΔFosB caused by dopamine depletion. L-dopa potentiated the upregulation of ΔFosB within the dopamine-depleted striatum and this effect was further enhanced by E2. We speculate that the potentiating effects of E2 on AIMs and on contralateral rotations could be explained by the molecular adaptations within the striatal medium spiny neurons of the direct and indirect striatofugal pathways.

Methamphetamine leads to the alterations of microRNA profiles in the nucleus accumbens of rats

CONTEXT

MicroRNA (miRNA) is an important regulator of gene expression. Methamphetamine (METH) induces a variety of alterations in different systems by affecting gene expression, but the effects of METH on miRNA profiles need to be elucidated.

OBJECTIVES

This study develops a rat model of METH addiction, and analyzes the expression profile alterations of miRNA in nucleus accumbens (NAc) of the METH-addicted rats.

MATERIALS AND METHODS

Sprague-Dawley rats were administered 10 mg/kg METH or vehicle twice a day for 4 weeks. The addictive behaviour of rats was estimated by CPP test. The pathological changes of brain tissues were then observed by HE and Glee silver staining. The miRNA profile analysis of the NAc of the rats was performed using an Illumina HiSeq™ 2500 sequencing system.

RESULTS

CPP test indicated that METH significantly prolonged the residence time of the rats in the drug box (from 307 ± 97 to 592 ± 96 s). The pathological staining showed the distorted axons, and fewer polarized neurons in the METH-treated rats. We further identified 40 differential miRNAs (17 up- and 23 down-regulated) and three novel miRNAs (novel 237, 296 and 501) that responded to METH. The bioinformatic analysis for the potential targets of the differential miRNA suggests that the downstream were concentrated in the Wnt signalling pathway, tuberculosis, toxoplasmosis, spliceosome, lysosome, and axon guidance.

DISCUSSION AND CONCLUSIONS

A number of miRNAs responding to METH were identified in the NAc of rats. These METH-regulated miRNAs provide a new perspective for revealing the molecular mechanisms of METH addiction.

Anatomy of Graft-induced Dyskinesias: Circuit Remodeling in the Parkinsonian Striatum

The goal of researchers and clinicians interested in re-instituting cell based therapies for PD is to develop an effective and safe surgical approach to replace dopamine (DA) in individuals suffering from Parkinson's disease (PD). Worldwide clinical trials involving transplantation of embryonic DA neurons into individuals with PD have been discontinued because of the often devastating post-surgical side-effect known as graft-induced dyskinesia (GID). There have been many review articles published in recent years on this subject. There has been a tendency to promote single factors in the cause of GID. In this review, we contrast the pros and cons of multiple factors that have been suggested from clinical and/or preclinical observations, as well as novel factors not yet studied that may be involved with GID. It is our intention to provide a platform that might be instrumental in examining how individual factors that correlate with GID and/or striatal pathology might interact to give rise to dysfunctional circuit remodeling and aberrant motor output.

Synaptotagmins in neurodegeneration

Synaptotagmins (Syts) are transmembrane proteins involved in the regulation of membrane trafficking. Here, we summarize literature data that provide growing evidence that several Syts are involved in the pathophysiological mechanisms of temporal lobe epilepsy and Parkinson's disease, as well as few reports related to brain ischemia and Alzheimer's disease (AD). We also report new data from our laboratories, showing changes of the expression of several Syts in Tg2576 mouse model of AD that may be related to neuroinflammation surrounding the beta-amyloid plaques. Furthermore, we demonstrate N-methyl-D-aspartate receptor-mediated upregulation of Syt 4 mRNA in a model of excitotoxic striatal lesion induced by unilateral striatal injection of quinolinic acid, associating the upregulation of Syt 4 with mechanisms of excitotoxicity. We propose that pharmacological manipulation of Syt expression in animal models of neurodegeneration should be further explored, as it may help to clarify the role of individual Syt isoforms in the regulation of membrane trafficking in neurodegeneration.