Impairment of mitochondria dynamics by human A53T α-synuclein and rescue by NAP (davunetide) in a cell model for Parkinson's disease.

The formation of oligomers and aggregates of overexpressed or mutant α-synuclein play a role in the degeneration of dopaminergic neurons in Parkinson's disease by causing dysfunction of mitochondria, reflected in their disturbed mobility and production of ROS. The mode of action and mechanisms underlying this mitochondrial impairment is still unclear. We have induced stable expression of wild-type, A30P or A53T α-synuclein in neuronally differentiated SH-SY5Y neuroblastoma cells and studied anterograde and retrograde mitochondrial trafficking in this cell model for Parkinson's disease. In contrast to wild-type and A30P, A53T α-synuclein significantly inhibited mitochondrial trafficking, at first retrogradely and in a later stage anterogradely. Accordingly, A53T α-synuclein also caused the highest increase in ROS production in the dysmobilized mitochondria in comparison to wild-type or A30P α-synuclein. Treatment with NAP, the eight amino acid peptide identified as the active component of activity-dependent neuroprotective protein (ADNP), completely annihilated the adverse effects of A53T on mitochondrial dynamics. Our results reveal that A53T α-synuclein (oligomers or aggregates) leads to the inhibition of mitochondrial trafficking, which can be rescued by NAP, suggesting the involvement of microtubule disruption in the pathophysiology of Parkinson's disease.

Behavioral meaningful opioidergic stimulation activates kappa receptor gene expression

The periaqueductal gray (PAG) has been reported to be a location for opioid regulation of pain and a potential site for behavioral selection in females. Opioid-mediated behavioral and physiological responses differ according to the activity of opioid receptor subtypes. The present study investigated the effects of the peripheral injection of the kappa-opioid receptor agonist U69593 into the dorsal subcutaneous region of animals on maternal behavior and on Oprk1 gene activity in the PAG of female rats. Female Wistar rats weighing 200-250 g at the beginning of the study were randomly divided into 2 groups for maternal behavior and gene expression experiments. On day 5, pups were removed at 7:00 am and placed in another home cage that was distant from their mother. Thirty minutes after removing the pups, the dams were treated with U69593 (0.15 mg/kg, sc) or 0.9% saline (up to 1 mL/kg) and after 30 min were evaluated in the maternal behavior test. Latencies in seconds for pup retrieval, grouping, crouching, and full maternal behavior were scored. The results showed that U69593 administration inhibited maternal behavior (P < 0.05) because a lower percentage of kappa group dams showed retrieval of first pup, retrieving all pups, grouping, crouching and displaying full maternal behavior compared to the saline group. Opioid gene expression was evaluated using real-time reverse-transcription polymerase chain reaction (RT-PCR). A single injection of U69593 increased Oprk1 PAG expression in both virgin (P < 0.05) and lactating female rats (P < 0.01), with no significant effect on Oprm1 or Oprd1 gene activity. Thus, the expression of kappa-opioid receptors in the PAG may be modulated by single opioid receptor stimulation and behavioral meaningful opioidergic transmission in the adult female might occur simultaneously to specific changes in gene expression of kappa-opioid receptor subtype. This is yet another alert for the complex role of the opioid ...

Behavioral meaningful opioidergic stimulation activates kappa receptor gene expression.

The periaqueductal gray (PAG) has been reported to be a location for opioid regulation of pain and a potential site for behavioral selection in females. Opioid-mediated behavioral and physiological responses differ according to the activity of opioid receptor subtypes. The present study investigated the effects of the peripheral injection of the kappa-opioid receptor agonist U69593 into the dorsal subcutaneous region of animals on maternal behavior and on Oprk1 gene activity in the PAG of female rats. Female Wistar rats weighing 200-250 g at the beginning of the study were randomly divided into 2 groups for maternal behavior and gene expression experiments. On day 5, pups were removed at 7:00 am and placed in another home cage that was distant from their mother. Thirty minutes after removing the pups, the dams were treated with U69593 (0.15 mg/kg, sc) or 0.9% saline (up to 1 mL/kg) and after 30 min were evaluated in the maternal behavior test. Latencies in seconds for pup retrieval, grouping, crouching, and full maternal behavior were scored. The results showed that U69593 administration inhibited maternal behavior (P < 0.05) because a lower percentage of kappa group dams showed retrieval of first pup, retrieving all pups, grouping, crouching and displaying full maternal behavior compared to the saline group. Opioid gene expression was evaluated using real-time reverse-transcription polymerase chain reaction (RT-PCR). A single injection of U69593 increased Oprk1 PAG expression in both virgin (P < 0.05) and lactating female rats (P < 0.01), with no significant effect on Oprm1 or Oprd1 gene activity. Thus, the expression of kappa-opioid receptors in the PAG may be modulated by single opioid receptor stimulation and behavioral meaningful opioidergic transmission in the adult female might occur simultaneously to specific changes in gene expression of kappa-opioid receptor subtype. This is yet another alert for the complex role of the opioid system in female reproduction.

Transcriptome analysis of nicotine-exposed cells from the brainstem of neonate spontaneously hypertensive and Wistar Kyoto rats.

In this study, the effects of nicotine on global gene expression of cultured cells from the brainstem of spontaneously hypertensive rat (SHR) and normotensive Wistar Kyoto (WKY) rats were evaluated using whole-genome oligoarrays. We found that nicotine may act differentially on the gene expression profiles of SHR and WKY. The influence of strain was present in 321 genes that were differentially expressed in SHR as compared with WKY brainstem cells independently of the nicotine treatment. A total of 146 genes had their expression altered in both strains after nicotine exposure. Interaction between nicotine treatment and the strain was observed to affect the expression of 229 genes that participate in cellular pathways related to neurotransmitter secretion, intracellular trafficking and cell communication, and are possibly involved in the phenotypic differentiation between SHR and WKY rats, including hypertension. Further characterization of their function in hypertension development is warranted.

The effects of social structure and sex-biased transmission on macroparasite infection.

Mathematical models of disease dynamics tend to assume that individuals within a population mix at random and so transmission is random, and yet, in reality social structure creates heterogeneous contact patterns. We investigated the effect of heterogeneity in host contact patterns on potential macroparasite transmission by first quantifying the level of assortativity in a socially structured wild rodent population (Apodemus flavicollis) with respect to the directly-transmitted macroparasitic helminth, Heligmosomoides polygyrus. We found the population to be disassortatively mixed (i.e. male mice mixing with female mice more often than same sex mixing) at a constant level over time. The macroparasite H. polygyrus has previously been shown to exhibit male-biased transmission so we used a Susceptible-Infected (SI) mathematical model to simulate the effect of increasing strengths of male-biased transmission on the prevalence of the macroparasite using empirically-derived transmission networks. When transmission was equal between the sexes the model predicted macroparasite prevalence to be 73% and infection was male biased (82% of infection in the male mice). With a male-bias in transmission ten times that of the females, the expected macroparasite prevalence was 50% and was equally prevalent in both sexes, results that both most closely resembled empirical dynamics. As such, disassortative mixing alone did not produce macroparasite dynamics analogous to those from empirical observations; a strong male-bias in transmission was also required. We discuss the relevance of our results in the context of network models for transmission dynamics and control.

Time course analysis of tyrosine hydroxylase and angiotensinogen mRNA expression in central nervous system of rats submitted to experimental hypertension.

Catecholaminergic and angiotensinergic systems are involved in the neural control of blood pressure. The present study analysed the expression of tyrosine hydroxylase (TH), a key enzyme for catecholamine synthesis and of angiotensinogen (AGT), the precursor of angiotensin II (Ang II), in areas of the central nervous system (CNS) involved with cardiovascular regulation such as nucleus tractus solitarius (NTS), ventrolateral medulla (VLM), locus coeruleus (LC) and hypothalamic paraventricular nucleus (PVN) 2 h, 3 and 7 days after aortic coarctated hypertensive rats. In situ hybridization, was employed for the analysis of messenger RNA (mRNA) expression with anatomical resolution. No changes were seen in TH and AGT mRNA expression in the analysed areas 2 h and 3 days after aortic coarctation when compared to the respective sham group. TH mRNA expression was increased in the NTS and LC of rats 7 days after coarctation hypertension when compared to sham rats. Time course analysis, showed an increase in TH mRNA expression in the NTS 7 days after aortic coarctation when compared to 2 h and 3 days groups, as well as an increase in LC 3 days and 7 days following coarctation hypertension in comparison with the 2 h group. Analysis of AGT mRNA in the NTS expression revealed a decrease at 3 days, followed by an increase in mRNA expression 7 days following coarctation hypertension when compared to the sham group. Time course analysis, showed an increase in AGT mRNA expression in the NTS 7 days after coarctation when compared to 2 h and 3 days groups. The results show that TH and AGT mRNA expression changes during the different phases of experimental hypertension, suggesting that the noradrenaline (NOR) and angiotensin II (Ang II) might participate in the modulation/maintenance of coarctation hypertension.

Decreases in the expression of CGRP and galanin mRNA in central and peripheral neurons related to the control of blood pressure following experimental hypertension in rats.

Calcitonin gene-related peptide (alpha CGRP) and galanin (GAL) are peptides known to participate in central mechanisms of blood pressure control. Nonetheless, variations in the synthesis of the peptides in response to a hypertensive challenge are not well described, specially using a model, which allows acute and chronic analyses. In this study, we have employed in situ hybridization to analyse changes in mRNA expression of alpha CGRP and GAL in the nucleus tractus solitarii (NTS), hypothalamic paraventricular nucleus (PVN) as well as petrosal and nodose ganglia after aortic coarctation-induced hypertension in rats. Acute (2h) and chronic (3 and 7 days) analyses were performed in order to evaluate the involvement of both peptides in different periods of hypertension. The analysis of relative mRNA levels showed significant differences between sham-operated and aortic coarcted hypertensive rats. alpha CGRP mRNA expression was decreased 2h (40%) and 3 days (42%) in nodose and petrosal ganglia, respectively, after coarctation. No changes in CGRP mRNA signal were seen in the NTS and PVN in the analysed periods. GAL mRNA expression was decreased in the NTS (19%) and PVN (55%), 3 and 7 days, respectively, after coarctation-induced hypertension. No changes in GAL mRNA expression were observed in petrosal and nodose ganglia following aortic coarctation. Data suggest that alpha CGRP and GAL may participate in the mechanisms involved in the establishment/maintenance of hypertension induced by aortic coarctation. Acute changes might be involved with the adaptation to the hypertensive state, while changes at the chronic phase might be related to counteraction of hypertension.

Change in the expression of NPY receptor subtypes Y1 and Y2 in central and peripheral neurons related to the control of blood pressure in rats following experimental hypertension.

Neuropeptide Y (NPY) is known to participate in central mechanisms of blood pressure control. However, variations on the expression of its receptors in response to a hypertensive challenge are not well defined, specially when considering that Y1 and Y2 often mediate opposite responses. In this study we have employed in situ hybridization to analyze changes in mRNA expression of NPY receptor subtypes Y1 and Y2 in the nucleus tractus solitarii (NTS), paraventricular nucleus of the hypothalamus (PVN) and petrosal and nodose ganglions 2 h, 3 and 7 days after aortic coarctation induced hypertension. Quantification by image analysis showed significant differences between sham-operated and aortic-coarcted hypertensive rats. Y1 receptor mRNA expression was increased (39%) in petrosal ganglion, 3 days after surgery. Y2 receptor mRNA expression was increased (143%) in the NTS of hypertensive compared with sham rats 2 h after surgery. Y2 receptor mRNA was decreased (62%) in the nodose ganglion of hypertensive compared with sham rats 2 h after surgery. No change was seen in Y1 and Y2 mRNA expression in the PVN in any analyzed period. The data suggest that NPY Y1 and Y2 receptors might participate in the mechanisms involved in the establishment/maintenance of hypertension induced by aortic coarctation. Acute changes seem to be involved with the adaptation to the new hypertensive state.

Quantitative autoradiography of adrenergic, neuropeptide Y and angiotensin II receptors in the nucleus tractus solitarii and hypothalamus of rats with experimental hypertension.

Catecholamines, neuropeptide Y (NPY) and angiotensin II (Ang II) are known to participate in the central control of blood pressure. However, the modulation of these neurotransmitter receptors in response to a hypertensive stimulus is not appropriately established. The purpose of the present study was to examine binding parameters of alpha(2)-adrenergic, NPY and Ang II receptors in the nucleus tractus solitarii (NTS) and paraventricular hypothalamic nucleus (PVN) following a hypertensive stimulus in the aortic-coarcted rat by means of quantitative receptor autoradiography. No changes were seen in binding parameters of alpha(2)-adrenergic and NPY receptors in the NTS of the hypertensive rat compared to control. However, an increased affinity (54%) of noradrenaline competing for 3H-PAC was seen in the PVN. Moreover, an increased binding (49%) of 125I-PYY was also observed in the PVN. The affinity of Ang II for 125I-Sar(1)Ile(8)-Ang II binding sites was also increased (57%) in the NTS of the hypertensive rat. No changes in the binding parameters of radioactive Ang II were observed in the PVN. The results suggest that systems involved with hypertension like Ang II in the NTS and catecholamines in the PVN might collaborate in the development/maintenance of high blood pressure in the aortic-coarcted rat.