山莨菪碱、旋覆花素、苦碟子对过度训练致急性心肌损伤大鼠的影响

目的探讨山莨菪碱、旋覆花素、苦碟子对过度训练致急性心肌损伤大鼠的影响。方法雄性Wistar大鼠80只,体重200～220 g,随机分为5组:正常对照组(C组,n=8)、力竭对照组(E组, n=24)、山莨菪碱组(A组,n=16)、旋覆花素组(IB组,n=16)、苦碟子组(IS组,n=16)。采用游泳致力竭建立过度训练动物模型。A组于力竭前即刻腹腔注射山莨菪碱10 mg/kg,IB组于力竭前24 h和力竭前即刻口腔灌入旋覆花素25 ml/kg,IS组于力竭前即刻腹腔注射苦碟子20 ml/kg。取标本检测大鼠血清磷酸肌酸激酶(CK)及其同工酶(CK-MB)的活性,光镜观察心肌组织形态学,采用流式细胞术及TUNEL法检测大鼠心肌细胞凋亡,并计算心肌细胞凋亡率。结果与C组比较,E组、A组、IB组和IS组血清CK及CK-MB升高,心肌细胞凋亡率升高(P<0.05);与E组比较,A组、IB组及IS组大鼠血清CK及CK-MB及心肌细胞凋亡率均降低(P<0.05)。光镜下,E组的心肌细胞核深染,有固缩现象;而A组、IB组及IS组的心肌心肌组织学变化均未见异常。结论山莨菪碱、旋覆花素、苦碟子预先给药通过抑制心肌细胞的凋亡,可减轻过度训练致大鼠的心肌损伤。     

The development of brain biogenic amines, cyclic nucleotides and hyperactivity in 6-OHDA-treated rat pups

Developmental changes in the behavior and brain biochemistry of rat pups were investigated in rats administered intracisternal injections of 6-hydroxydopamine (6-OHDA) or its vehicle at 5 days of age. Although pups of both groups were equivalent in their activity at 15 days of age, 6-OHDA-induced hyperactivity emerged at 20 and 30 days of age in a between-group design in which rats were only tested at one age. Body weight measurements revealed that 6-OHDA-treated rats were underweight at 15, 25 and 30 days of age. Furthermore, at 20 days of age, total activity was inversely related to body weights in the 6-OHDA-treated pups. Whole-brain levels of dopamine (DA) were decreased at every age by the 6-OHDA treatment, whereas norepinephrine (NE) levels were virtually unaffected by 6-OHDA at these same ages. Total activity was inversely correlated with whole-brain DA levels at 20 and 30 days of age when 6-OHDA-treated pups were hyperactive. Measures of cerebellar and "rest-of-brain" adenosine 3',5'-monophosphate (cyclic AMP) and guanosine 3',5'-monophosphate (cyclic GMP) were not uniformly altered by either the 6-OHDA treatment or by maturation. Results are discussed both in terms of brain biochemistry modulation of hyperactivity and the contribution of decreased body weights induced by 6-OHDA to the production of hyperactivity.     

Altered dopaminergic function in the prefrontal cortex, nucleus accumbens and caudate-putamen of an animal model of attention-deficit hyperactivity disorder — the spontaneously hypertensive rat

The spontaneously hypertensive rat (SHR) has been proposed as an animal model for Attention-Deficit Hyperactivity Disorder (ADHD). The behavioural problems of ADHD have been suggested to be secondary to altered reinforcement mechanisms resulting from dysfunction of the mesolimbic and mesocortical dopaminergic systems. The present study therefore investigated whether there are regional differences in dopamine (DA) and acetylcholine (ACh) release and DA D₂-receptor function in SHR compared to their normotensive Wistar-Kyoto (WKY) controls. The DA D₂-receptor agonist, quinpirole, caused significantly greater inhibition of DA release from caudate-putamen but not from nucleus accumbens or prefrontal cortex slices of SHR relative to WKY. DA D₂-receptor blockade by the antagonist, sulpiride, caused a significantly greater increase in DA release from nucleus accumbens slices of SHR compared to WKY suggesting increased efficacy of DA autoreceptors at low endogenous agonist concentrations in the nucleus accumbens of SHR. The electrically-stimulated release of DA was significantly lower in caudate-putamen and prefrontal cortex slices of SHR than in slices of WKY. This could be attributed to increased autoreceptor-mediated inhibition of DA release in caudate-putamen slices but not in the prefrontal cortex. No difference was observed between SHR and WKY with respect to DA D₂-receptor-mediated inhibition of ACh release from caudate-putamen or nucleus accumbens slices, suggesting that postsynaptic DA D₂-receptor function is not altered in SHR relative to WKY.     

Involvement of both cholinergic and catecholaminergic pathways in the central action of methylphenidate: A study utilizing lead-exposed rats

The effects of methylphenidate (MPH) and the cholinergic agonists nicotine and oxotremorine were tested on the spontaneous multiple unit activity in the mesencephalic reticular formation of two groups of rats. In control rats i.v. MPH (1 mg/kg), nicotine (0.125 mg/kg), and oxotremorine (0.5 mg/kg) all attenuated the unit activity with latencies of less than 10 min. In another group of rats, exposed to lead acetate since birth, the extent of attenuation of unit activity induced by MPH and nicotine was reduced and the latency of effect was delayed by 45–50 min. The latency of the oxotremorine effect was not changed but the attenuation of unit activity was more pronounced in the lead-treated group. Pretreatment with spiroperidol, to inhibit the aminergic receptors, diminished the inhibitory effect of MPH in the control group but not in the lead-treated group, whereas the attenuating effect of oxotremorine was not affected in either group. These data support our previous evidence that MPH exerts its action in the central nervous system by a cholinergic pathway in addition to published catecholaminergic pathways. Furthermore, the present findings indicate that chronic leadexposure in rats results in cholinergic hypofunction and supersensitivity at central cholinergic receptor sites. This alteration of central cholinergic function may be partially attributed to the malnutrition observed in the lead-exposed animals.Part of this work was presented in abstract form (Shih et al., 1976b)     

Effect of ambient temperature on hyperthermia and hyperkinesis induced by 3,4-methylenedioxymethamphetamine (MDMA or “ecstasy”) in rats

A stress-free, biotelemetric monitoring technique was used to investigate the effects of ambient temperature (T _a) on the hyperthermic and hyperkinetic effects of 3,4-methylenedioxymethamphetamine. In the first experiment a single injection of 5.0 or 7.5 mg/kg MDMA produced hyperthermia in rats maintained at aT _a of 24°C but hypothermia in rats maintained at aT _a of 11°C for 24 h prior to the injection. In contrast, hyperkinesis was induced at bothT _as. In the second experiment, the effects of acute MDMA administration was compared in rats maintained at a standardT _a of 24°C and in rats which were placed in a cool (11°C) room for a brief (90-min) period commencing 30 min after the injection. The brief exposure to the cool environment produced significant attenuation of MDMA-induced hyperthermia but did not affect the magnitude of hyperkinesis. The implications of the results for the understanding of the thermotoxic effects of MDMA in human drug users are discussed.     

山莨菪碱、旋覆花素和苦碟子对过度训练大鼠心肌Bcl-2和Bax蛋白表达的影响

目的探讨山莨菪碱、旋覆花素和苦碟子对过度训练大鼠心肌Bcl-2、Bax蛋白表达的影响。方法雄性Wistar大鼠80只,体重200～220 g,随机分为5组：正常对照组（C组,n=8）、力竭对照组（E组,n=24）、山莨菪碱组（A组,n=16）、旋覆花素组（IB组,n=16）、苦碟子组（IS组,n=16）。采用游泳至力竭建立过度训练动物模型,A组于力竭前即刻腹腔注射山莨菪碱10 mg/kg,IB组于力竭前24 h、即刻口腔灌入旋覆花素25 ml/kg,IS组于力竭前即刻腹腔注射苦碟子20 ml/kg。检测大鼠心肌Bax、Bcl-2蛋白的表达,并对Bax/Bcl-2蛋白比值与心肌细胞凋亡率进行相关性分析。结果与C组比较,E组Bax蛋白表达上调,Bcl-2蛋白表达下调,Bax/Bcl-2蛋白比值升高。A组、IB组和IS组Bax、Bcl-2蛋白表达上调,Bax/Bcl-2蛋白比值升高（P〈0.05）。与E组比较,A组、IB组和IS组Bax蛋白表达下调,Bcl-2蛋白表达上调,Bax/Bcl-2蛋白比值降低（P〈0.05）。各组Bax/Bcl-2蛋白比值与心肌细胞凋亡率呈正相关（r=0.727,P〈0.01）。结论山莨菪碱、旋覆花素和苦碟子预先给药可通过下调过度训练大鼠心肌促凋亡蛋白Bax、上调抗凋亡蛋白Bcl-2的表达,抑制心肌细胞凋亡。     

山莨菪碱对过度训练大鼠肾小管上皮细胞Toll样受体4表达的影响

目的 评价山莨菪碱对过度训练大鼠肾小管上皮细胞Toll样受体4(TLR4)表达的影响.方法 雄性SD大鼠48只,体重200～220 g,采用随机数字表法,将其随机分为3组:正常对照组(C组,n=8)、力竭运动组(E组,n=24)和山莨菪碱组(A组,n=16).采用大鼠游泳至力竭建立过度训练模型,A组于力竭运动前20 min腹腔注射山莨菪碱10 mg/kg后进行力竭运动.检测肾组织细胞凋亡和肾小管上皮细胞TLR4蛋白、TLR4 mRNA的表达水平.结果 与C组比较,E组和A组细胞凋亡率升高,肾小管上皮细胞TLR4蛋白和TLR4 mRNA表达上调(P＜0.05);与E组比较,A组细胞凋亡率降低,肾小管上皮细胞TLR4蛋白和TLR4 mRNA表达下调(P＜0.05).结论 山莨菪碱可通过下调过度训练大鼠肾小管上皮细胞TLR4表达,抑制肾脏细胞凋亡.     

山莨菪碱对过度训练致急性心肌损伤大鼠caspase-1和IL-18表达的影响

目的 评价山莨菪碱对过度训练致急性心肌损伤大鼠caspase-1和IL-18表达的影响.方法 健康雄性Wistar大鼠48只,体重200～ 220 g,采用随机数字表法,将其随机分为3组:对照组(C组,n=8)、力竭运动组(ES组,n=24)和山莨菪碱组(AD组,n=16).采用游泳力竭法建立过度训练致大鼠急性心肌损伤模型.AD组于力竭运动前20 min腹腔注射山莨菪碱10 mg/kg.ES组于力竭后即刻、6、24 h时,AD组于力竭后6、24 h时分别随机取8只大鼠,采集下腔静脉血样,采用ELISA法检测血清心肌肌钙蛋白I(cTnl)浓度,随后处死大鼠取心肌组织,采用免疫组化法检测caspase-1及IL-18的表达水平,光镜下观察病理学结果.结果 与C组比较,ES组各时点血清cTnI浓度升高,心肌组织caspase-1和IL-18表达上调(P＜0.05);与ES组比较,AD组各时点血清cTnI浓度降低,心肌组织caspase-1和IL-18表达下调(P＜0.05).AD组心肌病理学损伤程度轻于ES组.结论 山莨菪碱可减轻过度训练致大鼠急性心肌损伤,其机制与下调心肌组织caspase-1及IL-18表达有关.     

Attention-deficit/hyperactivity disorder (ADHD) behaviour explained by dysfunctioning reinforcement and extinction processes

Inattentiveness, overactivity and impulsiveness are presently regarded as the main clinical symptoms of attention-deficit/hyperactivity disorder (ADHD). Inattention is, however, a characteristic of most psychiatric disorders. It is argued that the ADHD Inattentive subtype may have heterogeneous origins and be qualitatively different from the ADHD Hyperactive/Impulsive subtype. At the neurobiological level, ADHD symptoms may to a large extent be caused by a dysfunctioning dopamine system: A dysfunctioning meso-limbo-cortical dopamine branch will produce altered reinforcement and extinction processes, on a behavioural level giving rise to deficient sustained attention, hyperactivity, motor and cognitive impulsiveness. A dysfunctioning nigro-striatal dopamine branch will cause ‘extrapyramidal’ symptoms. Our model disentangles the behaviours usually explained by ‘executive functions’ into cognitive impulsiveness, motor impulsiveness and deficient motor control. The various dopaminergic branches may not be equally dysfunctional in all individuals with ADHD. Etiologically, dopamine dysfunctioning will probably mainly be genetically determined while sometimes be induced by environmental factors like drugs of abuse or pollutants, which may explain geographical differences in prevalence rates.     

A Dose-Response and Time-Action Analysis of Autonomic and Behavioral Effects of Methylphenidate in Attention Deficit Disorder with Hyperactivity

Empirical attempts to correlate behavioral and physiological responses of hyperactive children to methylphenidate treatment have been complicated by methodological issues, including the demonstrated heterogeneity in the pool of hyperactive children, and the need to consider both dose-response and timeaction parameters of drug action. Ten hyperactive children, selected according to objective behavioral criteria, were each assessed in 3 placebo days and 3 drug treatment days varying in methylphenidate dosage. Heart rate, finger temperature, electrodermal variables, gross motor activity, serial reaction time (as a measure of attention), and impulsive errors of commission were measured before and at varying intervals following drug or placebo administration. Time-action curves of methylphenidate's effects on reaction time and on activity were dissimilar, with changes in reaction time more closely paralleling changes in the cardiovascular variables. These findings suggested that attentional deficit and inadequate motor inhibition represent divergent behavioral manifestations of hyperactivity, possibly corresponding to divergent neurophysiological substrates.