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Cholecystokinin (CCK) is one of the most studied neuropeptides in the brain. In this study, we investigated the effects of CCK-8s and LY225910 (CCK2 receptor antagonist) on properties of neuronal r...

Objectives Lack of high-quality sleep causes serious side effects. The current study aimed to investigate the impact of local extremely low frequency magnetic field (ELF-MF) on sleep and drowsiness in healthy young adults. Methods Sixty-five young adults (32 males and 31 females, aged 18-24, participated voluntarily in this randomized crossover clinical trial. 200 microTesla MF (3 minutes duration) at three frequencies (10, 14 and 18 Hz) was applied to the skull in areas C3, Cz and C4, respectively. The Stanford Sleepiness Scale (SSS) or Consciousness Test (CT), Epworth Sleepiness Scale (ESS) and Peabody Picture Vocabulary Test were used to evaluate drowsiness, sleepiness, and reaction time. These tests were done both before and after application of ELF-MF or sham operation. Results Minimum reaction time after exposure to ELF-MF increased compared to that before exposure (P = 0.03), while it was not significant for the sham group (P = 0.63). From the ESS questionnaire, the results indicated that there was no significant difference for males or females between the exposure and sham groups. The mean of the SSS scores was no different compared to that before exposure. Conclusion The results of this study demonstrated that exposure to ELF-MF may influence reaction time in young healthy people. However, as the results of ESS and SSS were not different between exposure and non-exposure groups, further studies using larger sample sizes are recommended in order to reach better interpretations of the effects of ELF-MF on sleepiness in young people.

The aim of this study was to evaluate the effect of orexin-A (OX-A) and the orexin-1 receptor antagonist SB-334867 (SB) on motor and cognitive functions in a rat model of Parkinson's disease.Parkinson was induced by intracerebroventricular (i.c.v) injection of 6- hydroxydopamine (6-OHDA) (200 μg/rat). 72 h later, the treatment was initiated by i.c.v administration of SB (30 nmol/rat) and/or OX-A (0.3 nmol/rat) for 10 days. Motor functions were monitored using rotarod and hanging tests. Cognitive function was assessed by passive avoidance test (Shuttle box). Results: OX-A administration in 6-OHDA treated rats remarkably increased the time which animals run on rod (in rotarod test) and also the latency to fall (in hanging test) (P 0.01 and P 0.001, respectively). Conversely, administration of SB in 6-OHDA-treated rats decreased the mentioned indices (P 0.05 for latency to fall). Administration of agonist and/or antagonist of orexin-1 receptors had no significant effect on 6-OHDA induced cognitive impairment in rats. Results of this study suggest that the orexinergic system might be involved in sensory-motor deficits of Parkinson's disease.

GABAC receptors are ligand-gated chloride channels and have important roles in some neurological functions like vision. Recent investigations demonstrated that these receptors are also expressed in the somatosensory cortex. In this study, we investigated the effect of (1,2,5,6-tetrahydropyridin-4-yl)methylphosphinic acid (TPMPA) (GABAC receptor antagonist) on the properties of the neuronal response to natural stimuli (whisker deflection) in deep layers of rat barrel cortex. Twenty-eight male Wistar rats, weighing 230-260 g, were used in this study. TPMPA (100 μmol/rat) was administered intracerebroventricularly (ICV). Neuronal responses to deflection of principal (PW) and adjacent (AW) whiskers were recorded in barrel cortex using tungsten microelectrodes. A computer-controlled mechanical displacement was used to deflect whiskers individually or in combination at 30 ms inter-stimulus intervals. ON and OFF responses for PW and AW deflections were measured. A condition-test ratio (CTR) was computed to quantify neuronal responses to whisker interactions. Our data suggest that ICV administration of TPMPA increased neuronal spontaneous activity, ON and OFF responses to PW, and/or AW deflections. However, CTR for neither ON nor OFF responses changed following TPMPA administration. The results of this study demonstrated that inhibition of GABAC receptors by TPMPA can modulate neuronal response properties in rat barrel cortex.

Objective: There is general agreement that norepinephrine could modulate neuronal responses to non-monoaminergic synaptic inputs in the somatosensory cortex. In the present study, we investigated the effect of central norepinephrine depletion on tactile learning in rats.Methods: Central norepinephrine depletion was induced using 50 mg/kg of N-(2-chloroethyl)-N-ethyl-2 bromobenzylamine (DSP-4) and verified by high performance liquid chromatography. Memory performance was assessed 1 and 5 weeks after DSP-4 treatment using novel object recognition test.Result: We observed a learning impairment in both DSP-4 groups, as the preference index was not significantly altered when compared to chance level (50%).Discussion: These findings suggest that depletion of central norepinephrine by DSP-4 leads to impairment of the tactile learning in rats, which can last at least for 35 days.