RAT DIAPHRAGM MUSCLE-CONTRACTION WITH AND WITHOUT OXYGEN ENRICHMENT

We investigated the effect of deprivation of oxygen circulation in the organ bath on the tension generation of the diaphragm in vitro. Adult male Swiss Albino rats were quickly killed and the left hemidiaphragms removed. Isolated phrenic nerve-diaphragmatic strip preparations were placed in an individual organ chamber containing Krebs solution and were connected to a force displacement transducer. The solution was maintained at 32 degrees C and bubbled with 95% O-2-5% CO2. For the measurement of isometric twitch characteristics, supramaximal voltage was delivered via phrenic nerve electrodes. After turning off the gas circulation, isometric twitch characteristics were determined at 5, 10, 15, and 20 minutes. Then the muscle was allowed to recover under aerobic conditions (i.e., while bathed in a fresh solution, gassed with 95% O-2-5% CO2). The isometric contractile properties were determined at the same intervals

Group I mGluRs positive allosteric modulators improved schizophrenia-related behavioral and molecular deficits in the Poly I:C rat model.

Rationale: Maternal polyinosinic-polycytidylic acid (Poly I:C) exposure leads to an increase in various proinflammatory cytokines and causes schizophrenia-like symptoms in offspring. In recent years, group I metabotropic glutamate receptors (mGluRs) have emerged as a potential target in the pathophysiology of schizophrenia.Objectives: The aim of our study was to investigate the behavioral and molecular changes by using the mGlu1 receptor positive allosteric modulator (PAM) agent RO 67-7476, and the negative allosteric modulator (NAM) agent JNJ 16259685 and the mGlu5 receptor PAM agent VU-29, and NAM agent fenobam in the Poly I:C-induced schizophrenia model in rats.Methods: Female Wistar albino rats were treated with Poly I:C on day 14 of gestation after mating. On the postnatal day (PND) 34-35, 56-57 and 83-84, behavioral tests were performed in the male offspring. On the PND84, brain tissue was collected and the level of proinflammatory cytokines was determined by ELISA method.Results: Poly I:C caused impairments in all behavioral tests and increased the levels of proinflammatory cytokines. While PAM agents caused significant improvements in prepulse inhibition (PPI), novel object recognition (NOR), spontaneous alternation and reference memory tests, they brought the levels of proinflammatory cytokines closer to the control group. NAM agents were ineffective on behavioral tests. It was observed that PAM agents significantly improved Poly I:C-induced disruption in behavioral and molecular analyses.Conclusions: These results suggest that PAM agents, particularly the mGlu5 receptor VU-29, are also promising and could be a potential target in schizophrenia

Effects of cigarette smoking on cognitive processing

Several previous studies have reported that cigarette smoking enhances performance of cognitive processing. These enhancements are generally attributed to the pharmacological effects of nicotine, while there is some debate whether the effects of smoking/nicotine are a result of recovery from abstinence. Evoked potentials (EPs) and event related potentials (ERPs) of the brain have been applied as an index of information processing in a wide variety of normal and cognitive impaired subjects. This study, was carried out on 20 health students (23 +/- 2.3 years old) from the medical faculty of 007 University. Study population. comprised ten chronic cigarette smokers consuming an average of 14 +/- 4.2 cigarettes per day, with a history of smoking for more than one year. Ten non-smokers served as control. Standard oddball paradigm was presented, and EEG activity was recorded at the F-z, C-z, P-z electrode sites. Twenty responses to target stimuli were averaged at each location. N1, P2, N2, and P300 components were evaluated in these recordings. Amplitudes were measured relative to prestimulus baseline, and peak latencies were defined as the time point of maximum amplitude. It was found that there were no significant differences between either N1, P2, N2, P300 amplitudes or peak latency values of cigarette smokers and non smokers. As a result, chronic cigarette smoking generally does not improve cognitive processing

The effect of sex differences on event-related potentials in young adults

Female/male cognitive differences have been studied for some time; however, such differences in Turkish population is unknown. Evoked potentials (EPs) of the brain have been applied as an index of information processing in a wide variety of normal and cognitive impaired subjects. Scalp event-related potentials (ERP) evoked by auditory stimuli were recorded in 20 male and 18 female neurologically and audiologically normal young Turkish subjects of 18 - 25 years (Av. 20.6) of age. Standard auditory "Oddball" paradigm involving simple discrimination task of concentrating on infrequent (target) stimulus and ignoring frequent (non-target) stimulus was employed. EEG activity was recorded at the Fz, Ct, Pt and Oz electrode sites of the 10-20 system using Ag/AgCl electrodes. Wave forms were collected and averaged off-line by a Pentium 100 computer, which also controlled the stimulus presentation. In general, significant main effects of gender and electrode site on evoked potential components were found. The interpeak amplitudes N1-P2 and N2-P3 were higher in the male subjects than in the female subjects at Cz. N2-P3 were higher in the male subjects than in the female subjects at Oz. The latencies of N1, P2, N2, P3 components were not different between both sex. For both sexes we found that N1-P2 amplitude was higher at Fz and Cz than Pz and Oz. N2-P3 amplitude was higher at Fz than Oz for only female subject. In male subjects, latency of N2 was longer at Fz than Oz. There were no significant differences in the latencies of N1,P2, and P3 components between electrode sites in both sexes. We suggest that ERP components could be affected by sex, electrode site, and cognitive performance

Zinc-induced alterations in contractile properties of rat diaphragm muscle in vitro

The effect of zinc ions on the isometric contraction of rat diaphragm muscles in the presence and in the absence of external calcium was studied. Using a transducer, the isometric force was measured as a function of supramaximal electrical stimulation, either directly or indirectly applied to the muscle. The following parameters were measured: peak twitch tension, PT, twitch contraction time, CT, relaxation half-time, RT-1/2, and peak rates of tension increase and decrease, +dP/dt and -dP/dt. The following zinc-induced alterations were observed: an increase of the PT; a decrease of the RT-1/2; an increase in the +dP/dt and -dP/dt. The CT was not changed significantly. Our results suggest that zinc ions have a positive inotropic effect on isolated diaphragm muscle. The increase in PT may be explained by a zinc-activated Ca2+ uptake by sarcoplasmic reticulum. This was followed by an increase in the rate of rise of tension development, which was secondary to increased -dP/dt. The mechanism(s) by which extracellular Ca2+ contributes to this action of zinc is not known

Habituation of the auditory evoked potential in a short interstimulus interval paradigm

The present experiment was carried out to investigate elicitation and habituation of the auditory event related potentials with stimulus trains utilizing a short interstimulus intervals (ISI) of 1500 ms. Scalp event related potentials elicited by auditory stimuli were recorded in 10 male subjects. Thirty auditory stimuli were presented binaurally over headphones to every subject with a duration of 1000 ms, each with a constant ISI of 1500 ms. No task relevance was given to the stimuli. Wave-forms were collected using a Pentium 100 computer

Effect of hyperglycemia on electrodermal activity in diabetic rats

This study investigated the relationship between hyperglycemia and electrodermal activity ( EDA) parameters in streptozotocin ( STZ) induced diabetic rats. The article evaluates the course of development of neurophysiological alterations in the peripheral nervous system in diabetic rats through EDA. Rats were made diabetic using a moderate dose of STZ ( DI) and high dose ( DII). The placebo group ( P) was injected with physiological saline. EDA was recorded 1 h before the injection ( beginning, 0, day), 1st day ( one day after the injection) and 10th day. Skin conductance level ( SCL) was lower in DII than P on the 1st and the 10th days. The SCL and SC fluctuation rate ( SCFr) of DI were significantly lower on the 10th day compared to their first record. SC response rate ( SCRr) was lower on the 10th day compared to the 1st day, in the DI. In the DI, SCL, SC fluctuation rate ( SCFr) and SC response rate ( SCRr) were lower on the 10th day compared to the 1st day. The DII was statistically higher in electrodermal non-responsiveness compared to other groups on the 1st day. The results obtained show that hyperglycemia affects the peripheral nervous system, and EDA parameters are affected by blood glucose level. It is suggested that EDA is a simple and non-invasive electrophysiological method in early diagnosis of diabetic neuropathy

Sex-related differences in time estimation and the role of expectancy

In this study, using auditory sequences, the authors designed on examination with three phases of stimulus-driven attention that is based on the possibility that involuntarily time shafts of attention tire caused by nonunique stimulus properties. The purpose was to investigate whether attending and temporal expectancies tire influenced by stimulus's properties and by sex. In each phase, an auditory stimulus train was presented, and the participant was asked to tap rhythmically in order to anticipate every fifth stimulus (or, in the third phase, the lack of it). The time between button pressing and stimulus onset was measured using a computer. Time estimating was accepted as a false response if the subject responded before 150 ins or 150 ms later from onset stimulus time. Error numbers were greater in Phase 3 and there was no significant difference between the male and female subjects for any of the phases when error numbers were compared. On the other hand, males pressed the button more accurately than females. lime estimation performance was affected by sex and expectancy-related motor responses are very important for time estimation