Differential Effects of Pentoxifylline on Learning and Memory Impairment Induced by Hypoxic-ischemic Brain Injury in Rats

OBJECTIVE: Hypoxic-ischemic (HI) brain injury in the human perinatal period often leads to significant long-term neurobehavioral dysfunction in the cognitive and sensory-motor domains. Using a neonatal HI injury model (unilateral carotid ligation followed by hypoxia) in postnatal day seven rats, the present study investigated the long-term effects of HI and potential behavioral protective effect of pentoxifylline. METHODS: Seven-day-old rats underwent right carotid ligation, followed by hypoxia (FiO2 = 0.08). Rats received pentoxifylline immediately after and again 2 hours after hypoxia (two doses, 60–100 mg/kg/dose), or serum physiologic. Another set of seven-day-old rats was included to sham group exposed to surgical stress but not ligated. These rats were tested for spatial learning and memory on the simple place task in the Morris water maze from postnatal days 77 to 85. RESULTS: HI rats displayed significant tissue loss in the right hippocampus, as well as severe spatial memory deficits. Low-dose treatment with pentoxifylline resulted in significant protection against both HI-induced hippocampus tissue losses and spatial memory impairments. Beneficial effects are, however, negated if pentoxifylline is administered at high dose. CONCLUSION: These findings indicate that unilateral HI brain injury in a neonatal rodent model is associated with cognitive deficits, and that low dose pentoxifylline treatment is protective against spatial memory impairment.

Effects of Chronic and Acute Lithium Treatment on the Long-term Potentiation and Spatial Memory in Adult Rats

OBJECTIVE: Although, accumulating evidence is delineating a neuroprotective and neurotrophic role for lithium (Li), inconsistent findings have also been reported in human studies especially. Moreover, the effects of Li infusion into the hippocampus are still unknown. The aims of this work were (a) to assess whether basal synaptic activity and long-term potentiation (LTP) in the hippocampus are different in regard to intrahippocampal Li infusion; (b) to assess spatial learning and memory in rats chronically treated with LiCO₃ in the Morris water maze. METHODS: Field potentials were recorded form the dentate gyrus, stimulating perforant pathways, in rats chronically (20 mg/kg for 40 days) or acutely treated with LiCO₃ and their corresponding control rats. In addition, performance of rats in a Morris water maze was measured to link behaviour of rats to electrophysiological findings. RESULTS: LiCO₃ infusion into the hippocampus resulted in enhanced LTP, especially in the late phases, but attenuated LTP was observed in rats chronically treated with Li as compared to controls. Li-treated rats equally performed a spatial learning task, but did spend less time in target quadrant than saline-treated rats in Morris water maze. CONCLUSION: Despite most data suggest that Li always yields neuroprotective effects against neuropathological conditions; we concluded that a 40-day treatment of Li disrupts hippocampal synaptic plasticity underlying memory processes, and that these effects of prolonged treatment are not associated with its direct chemical effect, but are likely to be associated with the molecular actions of Li at genetic levels, because its short-term effect preserves synaptic plasticity.

Auditory P300 Event-related Potential During Ramadan Intermittent Fasting

Background: P300 is an auditory evoked potential, called Endogenous Potential because it reflects the functional use which the individual makes of the auditory stimulus, being highly dependent on cognitive skills; among them we list 'attention' and 'auditory discrimination'. During the month of Ramadan, practising Muslims abstain from eating and drinking from sunrise to sunset. We aimed to investigate the effect of Ramadan fasting on the P300, a neurophysiological index of cognitive function. Material and Methods: 16 healthy male students [age ranging between 19 and 21 years] participated in this study. P300 was recorded with the auditory "oddball" two-tone discrimination task in Ramadan fasting and 1 month later during non-fasting period. The data from the central [Cz], frontal [Fz], parietal [Pz] and occipital [Oz] electrodes were analyzed. To determine if there is any correlation between blood glucose level changes and P300, glucose levels in both conditions also measured. Results and Discussion: The P300 latencies at Cz and Pz were prolonged in the fasting condition compared to non-fasting condition. The P300 amplitude at Oz was lower in the fasting condition compared to non-fasting condition. There was a strong correlation between mean glucose level and mean P300 latency at Oz of groups. Conclusion: The prolongation of P300 latencies and reduction of P300 amplitudes in some brain region provides the electrophysiological evidence for the presence of regional cognitive dysfunction in fasting condition and different components of the cognitive performance may be affected in these conditions.

P50 variations in Behcet's patients without neurologic findings

In the present study, subclinical lesion involvement was investigated using the P50 component in Behcet's patients without neurological manifestation. We performed this clinical research in Erciyes University, Faculty of Medicine between December 2000 and November 2001. The studies were carried out on 18 Behcet's patients without neurologic findings and 18 volunteers for control. Standard Ag/AgCl electrodes in plastic cups were used for monopolar EEG derivations. They were attached with electrode paste and tape at the Cz [vertex] according to the 10-20 system. The auditory stimuli were delivered in pairs. The P50 waves, which may be taken from approximately 50 msec from the stimuli, were collected by computer system. Amplitudes and latencies of the P50 components were measured in the same system. This study showed that the suppression of P50 responses performed by the test stimuli, was significantly more decreased in Behcet's patients than the control subjects. The decrease of the suppression of the auditory P50 response to repeated stimuli reflects a deficit in the central nervous system's ability, such as attention, cognition, and sensory input in Behcet's patients and can be used as a neurophysiological marker in subclinical lesions in these patients

effects of direction on saccadic eye movement parameters

The present study obtained saccadic eye movements form 25 right-handed normal subjects [aged 18 to 35 yrs., mean 22.4 yrs], to examine the effects of saccade direction on the saccadic parameters [latency, duration and average velocity]. The binocular saccadic eye movement were recorded with a direct-current electro-oculographic system, and analysis was performed on a laboratory digital computer. The LED larget positions were randomly selected 10, 15, 20, 25 and 30 degrees to the left or the right of the fixation points. Generally, mean values of the saccadic parameters over a large saccade angles were in agreement with those previously reported. These were no significant difference between saccades directed to the right and the left when all saccadic parameters were analyzed statistically

Effects of nicotine on pain and aggressivity and antagonism of these effects by mecamylamine

Nicotine caused a dose-dependent decrease [1.25 and 2.5 mg/kg] on writhing score of the mice, made painful by intraperitoneal [i.p.] acetic acid injection. At the dose of 0.75 mg/kg i.p. nicotine lowered attack score and time of the mice but there wasn't a significant change at 0.5 mg/kg dosage. These effect of nicotine were blocked by 2.5 mg/kg mecamlamine which was given 15 minutes before nicotine administration