Downregulation of lncRNA BACE1-AS improves dopamine-dependent oxidative stress in rats with Parkinson's disease by upregulating microRNA-34b-5p and downregulating BACE1.

Objective: Long noncoding RNAs (lncRNAs) have already been proposed to function in Parkinson's disease (PD). However, the role of lncRNA BACE1-AS in PD has never been discussed. This study aims to examine the mechanism of BACE1-AS on oxidative stress injury of dopaminergic neurons in PD rats.Methods: Rat models of PD were established through the injection of 6-hydroxydopamine. The rotation of rats was induced by intraperitoneal injection of apomorphine, and number of rotations per minute was detected. The levels of malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px), glutamic acid (Glu), dopamine (DA), tyrosine hydroxylase (TH), α-synuclein and inducible nitric oxide synthase (iNOS) in the substantia nigra of rats in each group were detected. Apoptosis and pathological changes in the substantia nigra were also observed. BACE1-AS, miR-34b-5p, BACE1, Bax and Bcl-2 expression in the substantia nigra were detected. The binding of BACE1-AS and miR-34b-5p and the targeting relationship of miR-34b-5p and BACE1 were further determined.Results: Downregulated BACE1-AS reduced iNOS, α-synuclein and Glu levels and elevated DA and TH levels in the substantia nigra of PD rats. Downregulated BACE1-AS repressed apoptosis and oxidative stress injury in the substantia nigra neurons of PD rats. BACE1-AS specifically bound to miR-34b-5p. BACE1 was a direct target gene of miR-34b-5p.Conclusion: Collectively, our study reveals that downregulation of lncRNA BACE1-AS inhibits iNOS activation in the substantial nigra and improve oxidative stress injury in PD rats by upregulating miR-34b-5p and downregulating BACE1.

Effect of selank on cognitive processes after damage inflicted to the cerebral catecholamine system during early ontogeny.

Effects of selank on learning, memory, and attention to sensory stimuli of different modality were studied in adult Wistar rats treated with 6-hydroxydopamine (neurotoxin selectively damaging catecholaminergic neurons and their terminals) during the first 3 days of life. Selank (300 microg/kg) restored cognitive processes disordered by chronic artificial inhibition of the cerebral catecholaminergic system.

[Biomedical aspects of health preservation strategy: role of catecholaminergic neuronal populations]. / Biomeditsinskie aspekty strategii sokhraneniia zdorov'ia: rol' katekholaminergicheskikh neironal'nykh populiatsii.

Lifestyle, environmental factors, genetics, and medical care are the main factors that determine the health status of man. Of particular attention are biological mechanisms ensuring the body's adaptation to constantly changing environmental conditions. The noradrenergic neuronal populations, the sympathetic nervous system in particular, modulate metabolic processes and supports a variety of activities, making them relevant to changing living conditions. There is a clear correlation between the life span and the number of sympathetic nerve cells functioning during postnatal ontogenesis. The exposures that reduce the activity of peripheral and central noradrenergic neurons and slow down aging processes in them loosen the relationships between the inner and outer world to prevent hyperactivity and to prolong life.

The effects of 5-hydroxydopamine on salivary flow rates and protein secretion by the submandibular and parotid glands of rats.

The secretory effects of 5-hydroxydopamine (5-OHDA) were tested in Nembutal-anaesthetized adult male Sprague-Dawley rats injected I.V. over a wide range of doses, with and without various autonomic antagonists and Ca2+ channel blockers. Polyacrylamide disc gel (15%) and iso-electric focusing (IEF) electrophoresis by the PhastSystem were used to separate and determine the types of protein in submandibular saliva. Amylase activity of parotid saliva was determined by the blue dextran method. Salivation by the submandibular glands following application of 5-OHDA was completely abolished by both prazosin and propranolol, whereas salivation by the parotid glands was completely abolished by propranolol alone. Following application of 5-OHDA, there was a dose-related increase in flow rates and total output of protein, but not in the protein concentration and amylase activity, from both salivary glands. The effect of 5-OHDA on submandibular saliva was significantly reduced by alpha-adrenoceptor blockers, but not by beta-adrenoceptor and cholinergic blockers, nor by any Ca2+ channel blocker. The effect of 5-OHDA on the parotid gland was not significantly altered by atropine and phentolamine. However, after pretreatment with reserpine, a 95% reduction was observed in the salivation from the submandibular gland. This implies that 5-OHDA is mostly acting indirectly via release of noradrenaline. The proteins in submandibular saliva following treatment with 5-OHDA alone or 5-OHDA in combination with beta-adrenoceptor blockers were mainly of the alpha-type, whereas after treatment with 5-OHDA in combination with alpha-adrenoceptor blockers they were of the beta-type. The alpha-type was found in saliva after treatment with each of three Ca2+ channel blockers.

Infusions of 6-hydroxydopamine into the nucleus accumbens abolish the analgesic effect of amphetamine but not of morphine in the formalin test.

The effects of bilateral infusions of 6-hydroxydopamine into the nucleus accumbens on analgesia produced by D-amphetamine and morphine were examined, in separate experiments, in the formalin test in rats. The lesions in the two experiments were not significantly different and dopamine in the nucleus accumbens, olfactory tubercle and striatum was depleted to 21.1%, 40.3% and 65.0% of control values, respectively. D-Amphetamine (0.75 and 2.0 mg/kg) and morphine (3.0 and 6.0 mg/kg) attenuated the response to formalin in unlesioned control rats. The analgesic effect of amphetamine was severely reduced by 6-hydroxydopamine lesions, and the residual analgesia was correlated with the amount of dopamine in the nucleus accumbens, but not with dopamine levels in the olfactory tubercle or striatum. Lesions also attenuated the locomotor stimulant effect of amphetamine. The analgesic effect of morphine was not altered by 6-hydroxydopamine infusions, nor was there any correlation between the analgesic effect of morphine and dopamine concentration in the nucleus accumbens, olfactory tubercle or striatum. The results indicate that the dopamine innervation of the nucleus accumbens is not critical for the analgesic effect of morphine but plays a major role in the analgesic effect of amphetamine.

Behavioral quantification of striatal dopaminergic supersensitivity after bilateral 6-hydroxydopamine lesions in the mouse.

Quantitative studies using dopamine (DA) agonist-induced rotational behavior after denervation have found that the behavioral sensitivity is much greater than would be predicted on the basis of striatal DA receptor upregulation alone. The sensitivity to DA agonists after chronic treatment with neuroleptics, which elicits striatal receptor alterations equal to denervation, displays increases more consistent with alterations in striatal receptor density. Since the behavioral paradigms used to assess agonist supersensitivity after denervation are different than that for chronic neuroleptic treatment (rotational vs. stereotypic behavior), we measured the behavioral supersensitivity after bilateral denervation using stereotypic behavior. The increase in sensitivity to apomorphine after bilateral nigrostriatal 6-hydroxydopamine lesions was consistent with the increases measured previously with rotational behavior. These data suggest that the quantitative difference observed in behavioral supersensitivity resulting from the different preparations lies with the biological consequences of denervation rather than with the behavioral paradigm.

The kappa-opioid receptor agonist spiradoline differentially alters the rotational response to dopamine D1 and D2 agonists.

The effect of the selective kappa-opioid agonist, spiradoline, on rotational behavior induced by a dopamine D1 or D2 agonist was examined in rats with a unilateral 6-hydroxydopamine lesion of the nigrostriatal pathway. Spiradoline reduced the rotational response to the D1 agonist SKF 38393 in a dose-dependent manner. Spiradoline had no effect on the total number of turns elicited by the D2 agonist quinpirole, but did alter the pattern of quinpirole-induced rotation at the highest dose tested. By itself, spiradoline did not have any obvious effects on motor behavior and did not cause rotation in either the ipsilateral or contralateral direction. These data suggest that kappa receptor stimulation, possibly mediated by the endogenous agonist dynorphin under physiological conditions, may function to dampen striatal output through the D1 receptor-regulated striatonigral pathway.

Spinal antinociception by adenosine analogs and morphine after intrathecal administration of the neurotoxins capsaicin, 6-hydroxydopamine and 5,7-dihydroxytryptamine.

The effects of intrathecal pretreatment with the neurotoxins capsaicin, 6-hydroxydopamine and 5,7-dihydroxytryptamine on spinal antinociception by adenosine analogs (NECA, 5'-N-ethylcarboxamido adenosine and CHA, N6-cyclohexyl adenosine) and morphine were examined using the rat tail flick and hot plate tests. Pretreatment with 50 micrograms capsaicin for 7 to 11 days (which reduced substance P immunoreactivity in the superficial layers of the dorsal spinal cord) produced a slight increase in the action of NECA and CHA, and reduced the action on morphine in the hot plate test but not in the tail flick test. Pretreatment with 50 to 100 micrograms 6-hydroxydopamine for 7 to 14 days (which reduced spinal cord noradrenaline levels by 54-65%) reduced spinal antinociception by NECA and CHA but not that by morphine. Pretreatment with 50 micrograms 5,7-dihydroxytryptamine (which reduced spinal cord serotonin levels by 74-89%) had no effect on any agent. Acute pretreatment with 7.5-30 micrograms phentolamine reduced the spinal antinociceptive action of noradrenaline, NECA and CHA, primarily in the hot plate test. Phentolamine (30 micrograms) also reduced the action of morphine (hot plate greater than tail flick), but did not affect the action of L-baclofen. These results suggest that spinal antinociception by adenosine analogs: 1) occurs primarily at a postsynaptic site of action (capsaicin results), and 2) is dependent on release of endogenous noradrenaline and activation of spinal adrenergic receptors (6-hydroxydopamine and phentolamine results). The reduction in the effect of morphine by capsaicin (removes a source of adenosine release) and phentolamine (antagonizes the action of endogenously released adenosine) can be explained in terms of the adenosine release hypothesis of morphine action within the spinal cord.

Degeneration of the nigral dopamine neurons after 6-hydroxydopamine injection into the rat striatum.

6-Hydroxydopamine (6-OHDA) was injected into the rat striatum unilaterally. After 2-4 weeks, a marked decrease in the number of tyrosine hydroxylase-immunoreactive neuronal perikarya and dendrites was observed in the substantia nigra (SN) ipsilateral to the injection. Nissl staining showed a severe cell loss in the same region and electron microscopy revealed neuronal perikarya under degenerating process in the SN. The results showed a retrograde cytotoxic effect of 6-OHDA from the striatal terminals to their dopaminergic neuronal perikarya in the SN, and suggest the possibility that the striatum may be a primary locus in the degeneration process in Parkinson's disease.

Effects of haloperidol administration on in vivo extracellular dopamine in striatum and prefrontal cortex after partial dopamine lesions.

The effects of haloperidol on striatal and prefrontal cortical extracellular fluid dopamine (DA) concentrations were examined in sham-operated control rats and in rats which had received partial lesions of their dopamine systems. In control rats haloperidol administration produced increases in extracellular fluid DA concentrations in both the striatum and prefrontal cortex. However, in rats which had been partially lesioned with intracerebroventricular 6-hydroxydopamine, haloperidol produced an increase in extracellular fluid DA concentration in the prefrontal cortex but failed to alter striatal DA release. These data suggest that nigrostriatal and mesocortical DA neurons have different response capabilities following partial DA lesions.

Enhanced norepinephrine release in hypothalamus from locus coeruleus in SHR.

The hypothesis that a functional projection from the locus coeruleus (LC) to the posterior hypothalamus contributes to the development of hypertension in SHR, was tested by measuring norepinephrine (NE) in the posterior hypothalamus by brain dialysis after injections of L-glutamate (L-glu) into LC. L-glu elicited a prolonged elevation of blood pressure in both SHR and WKY. Pressor effects were significantly larger in SHR than in WKY. Extracellular NE in the posterior hypothalamus increased after LC stimulation; NE release was significantly higher in SHR than in WKY. Injections of 6-hydroxydopamine (6-OHDA) into posterior hypothalamus lowered the resting blood pressure and attenuated the pressor responses to L-glu injections into the LC in SHR. These findings suggest that the LC projects functionally to the posterior hypothalamus and that the projection can contribute to the development of hypertension in SHR.

Modulation of the migrating myoelectric complex by brain noradrenergic systems in rats.

The respective role of central and peripheral noradrenergic systems in the control of migrating myoelectric complex (MMC) was investigated in rats following lesions with 6-hydroxydopamine (6-OHDA). 6-OHDA was injected via intraperitoneal (ip), intracisternal (icis), and intracerebroventricular (icv) routes in rats. Control animals received the vehicle alone. One month later, MMC was recorded in conscious rats chronically fitted with electrodes. The MMC period was significantly lengthened after 6-OHDA ip or icv injection, and slightly shortened after 6-OHDA icis injection. No disruption of central noradrenergic systems was detected after ip lesions. Norepinephrine content was reduced in the digestive tract after ip lesions, in the spinal cord after icis lesions, and in the cortex, the hypothalamus, pons-medulla, and the spinal cord after icv lesions. After icis lesions, noradrenergic perikarya were spared in pons-medulla, whereas only pons noradrenergic perikarya were lesioned after icv lesions. We conclude that lesions of brain noradrenergic systems modify MMC periodicity in rats. The rostral noradrenergic systems may play the major modulatory role.

Contribution of forebrain noradrenaline innervation to the central circulatory effects of alpha-methyldopa and 6-hydroxydopamine.

We studied the circulatory effects of chronic lesions of the ascending noradrenergic (NA) projections to the forebrain on the acute effects of intracisternal (i.c.) alpha-methyldopa (alpha-MD) and 6-hydroxydopamine (6-OHDA) on mean arterial pressure (MAP) and heart rate (HR) in conscious rabbits with arterial baroreceptors either intact or denervated (sinoaortic denervation, SAD). Both drugs acutely release neurotransmitter from central NA neurons. I.c. 6-OHDA produced acute hypertension and bradycardia while i.c. alpha-MD produced acute hypotension and bradycardia. The responses are qualitatively similar in SAD rabbits except that after 6-OHDA, HR increased. In another group we studied the effects of the drugs 3-4 weeks after localised injections of 6-OHDA in the midbrain dorsal and ventral NA bundles. Local 6-OHDA depleted forebrain regions of NA by 44-76%, and had no effects on basal values of MAP or HR. The pressor and depressor effects, of 6-OHDA and alpha-MD respectively, were little affected by the lesions in either intact or SAD rabbits. By contrast, in rabbits with intact baroreceptors, the lesion abolished the bradycardia produced by i.c. alpha-MD and 6-OHDA. The latter drug now produced a late tachycardia. In SAD rabbits, however, there was no effect on the alpha-MD-induced bradycardia, but the 6-OHDA tachycardia was enhanced. Since the major effects of the lesions were confined to the rabbits with intact baroreceptor afferents, it suggests that the ascending NA pathways are important for the cardiac responses dependent on baroreceptor input. In intact animals, both drugs produce bradycardia through facilitation of the vagal component of the baroreceptor-heart rate reflex. In SAD rabbits, almost all the changes to HR are mediated through the cardiac sympathetic and the lesions have little effect on HR.

Dopaminergic grafts in the striatum reduce D1 but not D2 receptor-mediated rotation in 6-OHDA-lesioned rats.

Rats received fetal dopaminergic neuronal grafts in the striatum and/or substantia nigra ipsilateral to a 6-hydroxydopamine (6-OHDA) lesion of the medial forebrain bundle (MFB). Dopaminergic grafts in the striatum substantially and significantly reduced turning elicited by the selective D1 agonist SKF 38393, but did not reduce turning elicited by the selective D2 agonist LY 171555. Thus, reduced turning in such grafted animals in response to non-selective dopaminergic agonists may be the result of diminished D1 supersensitivity. Fetal dopaminergic grafts in the ipsilateral substantia nigra (SN) did not augment the decreases in turning produced by concomitant ipsilateral dopaminergic grafts in the striatum in response to SKF 38393. LY 171555, D-amphetamine or L-DOPA. Dopaminergic grafts in the SN increased, while dopaminergic grafts in the striatum or in striatum and SN decreased, the facilitatory effect of D-amphetamine on rotation elicited by subsequent injection of dopamine agonists.

Naloxone reverses L-dopa induced overstimulation effects in a Parkinson's disease animal model analogue.

Chronic L-DOPA treatment of Parkinson's disease frequently leads to the development of motoric overstimulation and hyperkinetic movements. To investigate this problem in the laboratory, rats surgically altered by unilateral 6-hydroxydopamine lesions (6-OHDA) were chronically treated with one L-DOPA (10 mg/kg i.p.) injection per day for 20 days. In this 6-OHDA rotation model, the unilateral dopamine denervation results in a profound contralateral sensory-motor neglect and the animals spontaneously rotate in a direction ipsilateral to the dopamine depleted hemisphere. Initially, the L-DOPA treatment did not alter the response bias but after several weeks, the response bias was reversed and the animals rotated in the formerly akinetic direction, contralaterally, at a significantly higher level. Using this overstimulation effect as an analogue of the clinically observed L-DOPA overstimulation, animals were given naloxone in conjunction with the L-DOPA treatment. Naloxone (0.10, 0.25 and 0.50 mg/kg i.p.) produced a dose related decrease in the L-DOPA induced contralateral rotation. Consistent with an expected selective effect on the L-DOPA induced rotation, a dose related increase in ipsilateral rotation was observed. These results suggest that naloxone can attenuate the overstimulation effect of L-DOPA and that this effect is not attributable to non-specific response suppression effects.

Effects of injection mechanics, pH of infusate and 6-hydroxydopamine on cerebromicrovascular permeability in rats.

The effects of altering the rate, manner and vehicle used for intracerebral injection upon microvascular permeability were studied in Sprague-Dawley rats employing horseradish peroxidase histochemistry. The volume of vehicle delivered and the site of intracerebral injection were kept constant. In comparison to continuous infusion, vascular permeability was significantly greater following manual (intermittent) injections; however, no differences were found when the infusion rate was decreased 10-fold. Use of a buffered vehicle (Hanks' balanced salt solution) with pH adjusted to 7.4, in contrast to the more commonly used non-buffered vehicle (saline-ascorbate), resulted in significant reductions in permeability. The apparent influence of the agent 6-hydroxydopamine (6-OHDA) on changes in vascular permeability was found to vary depending on the type and pH of the vehicle used for injection. Significantly greater permeability resulted with saline-ascorbate (pH 3.1) as the vehicle when compared to Hanks' balanced salt solution (pH 7.4). Changes in vascular permeability can therefore be produced by varying mechanical and vehicular factors which, in the case of 6-OHDA, far outweigh previously reported permeability changes specifically attributed to this neurotoxin.

Lesions of the ventral noradrenergic bundle prevent the rise in blood pressure induced by social deprivation stress in the rat.

1. Hypertension can be induced by some types of stress in the rat. The aim of the present work was to study the putative implication of brain norepinephrine (NE) in blood pressure increase due to social deprivation stress. 2. The effects of 6-hydroxydopamine (6-OHDA) lesions of the ventral noradrenergic bundle (VNEB) on the hypertensive response induced by brief social deprivation stress in young Wistar rats were examined. NE, dopamine (DA), and epinephrine (EPI) levels were measured by HPLC coupled with electrochemical detection in two brain areas (hypothalamus and medulla oblongata) relevant for blood pressure regulation. 3. VNEB lesions prevented the hypertensive response produced by isolation. Twelve or 20 days after 6-OHDA administration, NE and EPI but not DA levels decreased in the hypothalamus of the lesioned rats. In contrast, no catecholamine changes were detected in medulla oblongata. 4. These data suggest that the VNEB plays a role in the triggering of the hypertensive response induced by social deprivation stress in young Wistar rats.

Influence of local injection of 5,7-DHT and 6-OH-DA into the neocortex on learning and exploratory behavior of rats in the open field.

The features of the exploratory behavior in the open field, of the learning of a conditioned-reflex food-procuring reaction, and of the shift in the level of biogenic amines of the brain was studied in Wistar rats with local injections of the specific neurotoxins 6-hydroxydopamine (6-OH-DA) and 5,7-dihydroxytryptamine (5,7-DHT). It was shown that damage to the structure of the serotoninergic or catecholaminergic systems of the frontal cortex and hippocampus caused by local injection of 6-OH-DA and 5,7-DHT into the neocortex is accompanied by multidirectional changes in the exploratory behavior and learning of the animals.

[Right/left discrimination learning in rat pups neonatally treated with 6-hydroxydopamine].

At 2 and 4 days of age, rat pups were treated with 6-hydroxydopamine (6-OHDA; 70 micrograms, ivt) following desmethylimipramine (20 mg/kg, sc) pretreatment. Spontaneous activity test in a novel cage at 16 and 17 days of age revealed a sustained higher level of locomotor activity in 6-OHDA-treated rats, which was characterized by a deficit of habituation. For right/left discrimination learning trained from 18 days of age, "homing" was used as an reinforcer, i.e., pups could enter the goal area adjacent to home cage if they chose a predetermined correct arm of T-maze. Rats were trained 10 trials a day until they attained the learning criterion (at least 17 correct choices in 2 days). Thereafter, they were re-trained for the reversal learning to the criterion (at least 8 correct choices in a day). 6-OHDA-treated rats were required significantly more trials to attain the learning criterion both in the original and the reversal learnings. Biochemical assay confirmed a marked depletion of brain dopamine contents in striatum, cortex and midbrain with thalamus in 6-OHDA-treated rats. Therefore, the neonatal depletion of brain dopamine produced hyperactivity (habituation deficit) and a discrimination deficit during the developmental period.

Mediation of micturition reflex by central norepinephrine from the locus coeruleus in the cat.

We examined whether norepinephrine originating in the locus coeruleus mediates the micturition reflex in anesthetized cats. 6-Hydroxydopamine, a catecholamine neurotoxin, injected bilaterally into the locus coeruleus markedly decreased catecholamine fluorescence in the lesioned area and induced urinary retention after 72 to 84 hr. At this time, there was no or only slight contraction of the urinary bladder induced by its distension, while the contraction was noted before the treatment. However, phenylephrine, an alpha 1-receptor agonist, applied intrathecally in 6-hydroxydopamine-treated animals induced moderate bladder contraction. In sham-operated animals, the bladder contraction on its distension was inhibited by intrathecally applied prazosin, an alpha 1-receptor antagonist. Thus, in the micturition reflex, norepinephrine derived from the locus coeruleus acts on the alpha 1-adrenergic receptors in the sacral cord, and induces urinary bladder contraction via activation of the sacral parasympathetic preganglionic neurons.