α-Synuclein mRNA and soluble α-synuclein protein levels in post-mortem brain from patients with Parkinson's disease, dementia with Lewy bodies, and Alzheimer's disease.

α-Synuclein is a neuronal protein implicated in the etiology of Parkinson's disease (PD) and dementia with Lewy bodies (DLB). Whilst increased α-synuclein expression due to gene duplication or triplication can cause familial PD, previous studies of α-synuclein levels in idiopathic disease have produced conflicting data. We quantified α-synuclein mRNA and soluble protein in five human post-mortem brain regions from four groups of individuals with PD, DLB, Alzheimer's disease (AD) and matched controls. α-Synuclein mRNA levels, measured using quantitative real-time PCR, did not differ significantly between groups in any brain regions examined. In contrast, levels of soluble α-synuclein protein, measured by ELISA, were significantly lower in 4 of the 5 regions for patients with DLB, and in 2 of the 5 regions for patients with PD, compared to controls. Soluble α-synuclein protein levels were not significantly different in the AD patients, compared to controls, in 4 of the 5 regions. This study indicates that although levels of soluble α-synuclein protein are lower in DLB and PD, there is no evidence for a corresponding decrease in α-synuclein mRNA levels. This might result from altered translation, or removal of α-synuclein protein from a soluble detectable state, either by turnover or conversion to an insoluble form.

Feeding association between the nucleus of the solitary tract and the ventral tegmental area.

Male Sprague-Dawley rats were fitted with two cannulae in the VTA and one cannula in the NTS for co-administration of the micro-opioid receptor agonist DAMGO in one site and the opioid antagonist naltrexone in the other. Injection of DAMGO into the VTA or the NTS stimulated feeding. The increase in food intake after DAMGO injection into the VTA was decreased following injection of naltrexone into the NTS. Furthermore, the increase in food intake after DAMGO injection into the NTS was decreased following injection of naltrexone into the VTA. These results suggest an opioid-mediated feeding association between the VTA and NTS.

Identification of valid reference genes for the normalization of RT qPCR gene expression data in human brain tissue.

BACKGROUND: Studies of gene expression in post mortem human brain can contribute to understanding of the pathophysiology of neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD) and dementia with Lewy bodies (DLB). Quantitative real-time PCR (RT qPCR) is often used to analyse gene expression. The validity of results obtained using RT qPCR is reliant on accurate data normalization. Reference genes are generally used to normalize RT qPCR data. Given that expression of some commonly used reference genes is altered in certain conditions, this study aimed to establish which reference genes were stably expressed in post mortem brain tissue from individuals with AD, PD or DLB. RESULTS: The present study investigated the expression stability of 8 candidate reference genes, (ubiquitin C [UBC], tyrosine-3-monooxygenase [YWHAZ], RNA polymerase II polypeptide [RP II], hydroxymethylbilane synthase [HMBS], TATA box binding protein [TBP], beta-2-microglobulin [B2M], glyceraldehyde-3-phosphate dehydrogenase [GAPDH], and succinate dehydrogenase complex-subunit A, [SDHA]) in cerebellum and medial temporal gyrus of 6 AD, 6 PD, 6 DLB subjects, along with 5 matched controls using RT qPCR (TaqMan(R) Gene Expression Assays). Gene expression stability was analysed using geNorm to rank the candidate genes in order of decreasing stability in each disease group. The optimal number of genes recommended for accurate data normalization in each disease state was determined by pairwise variation analysis. CONCLUSION: This study identified validated sets of mRNAs which would be appropriate for the normalization of RT qPCR data when studying gene expression in brain tissue of AD, PD, DLB and control subjects.

A bi-directional mu-opioid-opioid connection between the nucleus of the accumbens shell and the central nucleus of the amygdala in the rat.

The central nucleus of the amygdala (CeA) and the nucleus of the accumbens shell (NAc) have been shown to be involved in opioid-mediated feeding behavior. The present study examined whether mu-opioid signalling between the CeA and NAc affected feeding. Male Sprague-Dawley rats were fitted with one cannula placed in the CeA and two cannulae placed in the NAc, which allowed for coadministration of the mu-opioid receptor agonist [D-Ala(2), NMe-Phe(4), Gly-ol(5)]-enkephalin (DAMGO) in one site and the opioid antagonist naltrexone (NTX) in the other site. Single injection of DAMGO (2.4 nmol) into the CeA and bilateral injections of DAMGO (2.4 nmol) into the NAc stimulated feeding (P<0.05). The DAMGO-induced increase of food intake following injection into the CeA was decreased by bilateral injection of NTX (13.2 and 26.5 nmol) into the NAc at 2- and 4-h postinjections (P<0.05). In the reverse situation, the DAMGO-induced increase of food intake following injection into the NAc was decreased by injection of NTX (13.2 and 26.5 nmol) into the CeA at 1-, 2-, and 4-h postinjections (P<0.05). These results suggest that a bi-directional mu-opioid-opioid signalling pathway exists between the CeA and the NAc, which influences feeding.

Evidence for a mu-opioid-opioid connection between the paraventricular nucleus and ventral tegmental area in the rat.

The paraventricular nucleus (PVN) and the ventral tegmental area (VTA) have been shown to be involved in opioid mediated feeding behavior. The present study examined whether mu-opioid signalling between the PVN and VTA affected feeding behavior. Male Sprague-Dawley rats were cannulated with one cannula placed in the PVN and two cannulae placed in the VTA, which allowed for co-administration of the mu-opioid receptor agonist [D-Ala(2), NMe-Phe(4), Gly-ol(5)]-enkephalin (DAMGO) in one site and the opioid antagonist naltrexone (NTX) in the other site. Bilateral administration of DAMGO (1.2, 2.4 and 4.9 nmol) into the VTA stimulated feeding dose dependently at 2.4 and 4.9 nmol (P<0.05). The DAMGO (2.4 nmol)-induced increase of food intake following injection into the PVN was blocked by bilateral injection of NTX (6.6, 13.2 and 26.5 nmol) into the VTA at 2 and 4 h (P<0.05). In the reverse situation, the DAMGO (2.4 nmol)-induced increase of food intake following injection into the VTA was blocked by injection of NTX (13.2 and 26.5 nmol) into the PVN at 2 and 4 h (P<0.05). The present study suggests that a bidirectional mu-opioid-opioid signalling pathway exists between the PVN and the VTA which influences feeding.