Acute interactions between -DOPA and the neurotoxic effects of 1-methyl-4-phenylpyridinium or 6-hydroxydopamine in mice

We have compared the effects of an i.p. pretreatment with L-DOPA (200 mg/kg) associated with benserazide (25 mg/kg) on neurotoxic effects of either 6-hydroxydopamine (6-OHDA) (50 microg, 10 microl per mouse) or 1-methyl-4-phenylpyridinium (MPP+) (17.5 microg, 10 microl per mouse). The striatal dopamine (DA) content, the vesicular monoamine transporter (VMAT2) density, as well as the hypothalamic norepinephrine (NE) content were measured 8 days after treatments. The L-DOPA-benserazide pretreatment worsened by 65% the 6-OHDA-induced depletion in striatal DA. On the contrary, it reduced by 42% the MPP+-induced depletion in striatal DA and by 54% the MPP+-induced decrease in VMAT2 density. It was noticed that the L-DOPA-benserazide pretreatment did not modify the marked decrease in hypothalamic NE content induced by 6-OHDA.     

Modulation of auditory cortex unit activity during the performance of a conditioned response

Single-unit activity in primary auditory cortex was studied in unanesthetized, paralyzed cats during the performance of a classical conditioning task. The conditioned stimulus was a 0.5-s white noise (WN) burst paired with tail shock delivered 4.5 s later. Cats habituated to WN without shock served as controls. Overlayed on these tasks was a continuous background of 1/s, behaviorally irrelevant, 100-ms duration tone bursts set to the best frequency and optimal intensity for the particular unit being studied. Spontaneous activity and tone responses following WN were compared with the respective activity preceding WN. The spontaneous or evoked activity of 75% of the cells recorded in the trained animals changed significantly after WN, whereas the activity of 28% of the cells recorded in habituated animals changed. Augmentation and suppression of both spontaneous and evoked activity were found. These results have implications for the encoding of acoustic stimuli in terms of the modulation of lemniscal sensory system activity.     

Replication cycle of chikungunya: A re-emerging arbovirus

Arboviruses (or arthropod-borne viruses), represent a threat for the new century. The 2005-2006 year unprecedented epidemics of chikungunya virus (CHIKV) in the French Reunion Island in the Indian Ocean, followed by several outbreaks in other parts of the world such as India, have attracted the attention of clinicians, scientists, and state authorities about the risks linked to this re-emerging mosquito-borne virus. CHIKV, which belongs to the Alphaviruses genus, was not previously regarded as a highly pathogenic arbovirus. However, this opinion was challenged by the death of several CHIKV-infected persons in Reunion Island. The epidemic episode began in December 2005 and four months later the seroprevalence survey report indicated that 236,000 persons, more than 30% of Reunion Island population, had been infected with CHIKV, among which 0.4-0.5% of cases were fatal. Since the epidemic peak, the infection case number has continued to increase to almost 40% of the population, with a total of more than 250 fatalities. Although information available on CHIKV is growing quite rapidly, we are still far from understanding the strategies required for the ecologic success of this virus, virus replication, its interactions with its vertebrate hosts and arthropod vectors, and its genetic evolution. In this paper, we summarize the current knowledge of CHIKV genomic organization, cell tropism, and the virus replication cycle, and evaluate the possibility to predict its future evolution. Such understanding may be applied in order to anticipate future epidemics and reduce the incidence by development and application of, for example, vaccination and antiviral therapy.     

Age-related changes in the acoustic startle reflex in Fischer 344 and Long Evans rats

The behavioral consequences of age-related changes in the auditory system were studied in Fischer 344 (F344) rats as a model of fast aging and in Long Evans (LE) rats as a model of normal aging. Hearing thresholds, the strength of the acoustic startle responses (ASRs) to noise and tonal stimuli, and the efficiency of the prepulse inhibition (PPI) of ASR were assessed in young-adult, middle-aged, and aged rats of both strains. Compared with LE rats, F344 rats showed larger age-related hearing threshold shifts, and the amplitudes of their startle responses were mostly lower. Both rat strains demonstrated a significant decrease of startle reactivity during aging. For tonal stimuli, this decrease occurred at an earlier age in the F344 rats: middle-aged F344 animals expressed similar startle reactivity as aged F344 animals, whereas middle-aged LE animals had similar startle reactivity as young-adult LE animals. For noise stimuli, on the other hand, a similar progression of age-related ASR changes was found in both strains. No significant relationship between the hearing thresholds and the ASR amplitudes was found within any age group. Auditory PPI was less efficient in F344 rats than in LE rats. An age-related reduction of the PPI of ASR was observed in rats of both strains; however, a significant reduction of PPI occurred only in aged rats. The results indicate that the ASR may serve as an indicator of central presbycusis.     

Cyperus esculentus L. and Tetracarpidium conophorum Müll. Arg. Supplemented Diet Improved Testosterone Levels,Modulated Ectonucleotidases and Adenosine Deaminase Activities in Platelets from L-NAME-Stressed Rats

In hypertensive individuals, platelet morphology and function have been discovered to be altered, and this has been linked to the development of vascular disease, including erectile dysfunction (ED). The impact of nutritional supplementation with Cyperus esculentus (tiger nut, TN) and Tetracarpidium conophorum (walnut, WN) on androgen levels, ectonucleotidases, and adenosine deaminase (ADA) activities in platelets from L-NAME (Nω-nitro-L-arginine methyl ester hydrochloride) challenged rats were investigated. We hypothesized that these nuts may show a protective effect on platelets aggregation and possibly enhance the sex hormones, thereby reverting vasoconstriction. Wistar rats (male; 250–300 g; n = 10) were grouped into seven groups as follows: basal diet control group (I); basal diet/L-NAME/Viagra (5 mg/kg/day) as positive control group (II); ED-induced group (basal diet/L-NAME) (III); diet supplemented processed TN (20%)/L-NAME (IV); diet supplemented raw TN (20%)/L-NAME (V); diet supplemented processed WN (20%)/L-NAME (VI); and diet supplemented raw WN (20%)/L-NAME (VII). The rats were given their regular diet for 2 weeks prior to actually receiving L-NAME (40 mg/kg/day) for ten days to induce hypertension. Platelet androgen levels, ectonucleotidases, and ADA were all measured. L-NAME considerably lowers testosterone levels (54.5 ± 2.2; p < 0.05). Supplementing the TN and WN diets revealed improved testosterone levels as compared to the control (306.7 ± 5.7), but luteinizing hormone levels remained unchanged. Compared to control groups, the L-NAME-treated group showed a rise in ATP (127.5%) hydrolysis and ADA (116.7%) activity, and also a decrease in ADP (76%) and AMP (45%) hydrolysis. Both TN and WN supplemented diets resulted in substantial (p < 0.05) reversal effects. Enhanced testosterone levels and modulation of the purinergic system in platelets by TN and WN could be one of the mechanisms by which they aid in vasoconstriction control.     

猫ABR两耳相互作用的研究

用不同声强的稳态WN和Click同时分别刺激猫的两耳,观察记录负荷WN侧耳蜗破坏前后的ABR,探讨对侧耳负荷的WN对ABR的影响规律及其可能的机制。结果表明,耳蜗破坏前,负荷40dB和75dB WN时,对0dB,45dB,70dB及75dB Click记录的ABR各波振幅均有明显影响(P<0.05～0.01)。耳蜗破坏后,同样条件下记录的ABR振幅基本无明显变化(P>0.05)。提示耳蜗破坏前的ABR振幅变小可能是由于两种声信号在脑干听觉通路上传时产生了抑制性BI,即WN信号对Click信号有一定干涉作用。70dBClick(75dB WN)时P_1波振幅减小与中枢的离中控制相关。     

湿热内蕴与脾肾阳虚型溃疡性结肠炎患者Thl／Th2的状态

目的研究湿热内蕴型和脾肾阳虚型溃疡性结肠炎患者白细胞介素2（IL-2）、IL-4、IL-10和干扰素7（IFN-γ）的变化，以观察不同证型Th1／Th2的状态。方法收集20例溃疡性结肠炎患者（湿热内蕴型和脾肾阳虚型各10例），并与10例正常人对照，用放射免疫法测定患者血清中IL-2和IL-10的浓度，用酶联免疫吸附法（ELISA法）测定患者血清中IL-4和IFN-γ浓度，测定IL-2／IL-10比值和IFN-γ／IL-4比值。结果湿热内蕴组患者IL-2升高明显，其炎症反应属于IL-2诱导的Th1．型免疫反应，而脾肾阳虚组患者IL-10升高明显，属于Th2型免疫反应。结论湿热内蕴型患者主要是以Th1。型免疫反应为主，而脾肾阳虚型患者主要以仉型免疫反应为主。