Effects of puerarin on spatial learning and memory function in mice with acute alcohol consumption: An evaluation based upon firing rate and oxygen saturation analysis.

BACKGROUND: Ethanol is associated with various medical comorbidities affecting the brain and central nervous system. OBJECTIVES: The use of puerarin in treating alcohol-induced memory disorders is systematically evaluated in this study based upon an analysis of the firing rate and oxygen saturation (SO2). MATERIAL AND METHODS: A multi-channel data acquisition system and near-infrared spectroscopy (NIRS) were combined to obtain the electroneurophysiological signals and SO2 in the hippocampus of mice from the Institute of Cancer Research (ICR) after ethanol injection. A T-maze test was performed to study the alteration of spatial memory function. Ethanol was administered intraperitoneally (i.p.) in 2 dosages (1.5 g/kg and 0.5 g/kg). To investigate the effects of puerarin against acute ethanol-induced memory impairment, the same parameters corresponding to electroneurophysiological signals, SO2 and behavior performance in mice were also recorded upon the supplementation of puerarin in 2 dosages (25 mg/kg and 50 mg/kg). RESULTS: An inhibited firing rate and decreased SO2 were found in mice treated with an ethanol dose of 1.5 g/kg, which resulted in a low correct choice rate in the T-maze test, while an opposite trend appeared in mice which had been administered a moderate ethanol dose (0.5 g/kg). The trend of SO2 was positively correlated with that of the firing rate. A decreased firing rate and SO2 were accompanied by a decrease in the correct choice rate. With the supplementation of puerarin, a significant increase in the mean firing rate and SO2, as well as an improved correct choice rate, can be found in mice injected with excessive ethanol. CONCLUSIONS: The electroneurophysiological signals and NIRS were combined for the first time to prove that an excessive intake of ethanol can inhibit the spatial learning and memory function of mice. The supplementation of puerarin can suppress these adverse effects induced by ethanol at a high dosage, as evidenced by the increased firing rate and SO2.

Theta-gamma coupling in hippocampus during working memory deficits induced by low frequency electromagnetic field exposure.

The dramatically increased use of electricity is raising major concerns as to the consequences of the interaction between electromagnetic field (EMF) and neurobiology. The aim of this study is to investigate the effects of magnetic field on working memory in the hippocampal region by analyzing local field potentials (LFPs) and spikes pattern in vivo. In present study, mice were exposed to EMF (50Hz, 1mT), static magnetic field (SMF, 1mT), or placed in the exposure tube but without EMF exposure (SHAM), respectively. During the exposure for 7 consecutive days, mice were subjected to perform working memory (WM) tasks in Y-maze, and multichannel electrophysiology signals from hippocampus of mice were recorded during the test, from which LFPs, spike firing rates, band power at different frequencies, and theta-gamma modulation index (MI) were analyzed in details. From our results, correct choice rate during WM task was found significantly decreased in EMF group after 3-day exposure, which was consistent with noticeable decline in firing rate. Starting from Day 3 after EMF exposure, the power of theta (4-12Hz) and gamma (LG, 30-60Hz) before reference point (RP) in Y-maze were also found to be descending, together with decrease of oscillatory activities of theta and gamma frequencies. The results indicated that MI between theta and gamma could play a significant role in modulating the spikes discharge and encoding WM. Therefore, the analysis of theta-gamma coupling and its oscillation strength may provide a new perspective for mechanistic investigation of EMF-induced WM deficits.

Effect of Acute Ethanol Administration on the Hippocampal Region Neural Activity Using a Microelectrode Array.

BACKGROUND: Because acute ethanol (EtOH) administration is known to influence cognitive processes by impairing hippocampal function, electrophysiological responses of the hippocampus following EtOH exposure warrant investigation. To mimic in vivo conditions, we recorded and analyzed critical firing characteristics of the neuronal population dynamically, particularly in the hippocampal region, before and after acute EtOH administration. METHODS: Microelectrodes were inserted in the hippocampus CA1 region of 21 Institute of Cancer Research mice. The mice were divided into 3 groups, including an EtOH injection group (1.5 g/kg), a saline injection group (1.5 g/kg), and a negative control group that received no injection. A data acquisition system was employed to detect the local field potentials (LFPs) and spike potentials following acute EtOH administration. Various multichannel electrophysiological signals were collected in vivo in each group at 60 minutes, from which the firing rate and wavelet entropy (WE) were analyzed further. RESULTS: Firing rates began to decline at 20 minutes postinjection and then gradually recovered from 40 to 60 minutes. In contrast, 20 minutes post-injection, WE increased maximally and then returned to normal from 40 to 60 minutes (p < 0.05). Pronounced changes in the relative energy of theta and alpha oscillations were also observed after 20 minutes of alcohol exposure and recovery occurred by 60 minutes (p < 0.05). CONCLUSIONS: A major mechanism of EtOH's action on the hippocampus is neurotransmitter blocking in the form of excitatory neuron inhibition in vivo. Changes in hippocampal spikes coincided with changes in LFPs during the entire time course of acute EtOH administration. The correlation between spikes and LFPs suggests that they jointly affect encoding in hippocampus.

Oviposition deterrents from eggs of the cotton bollworm, Helicoverpa armigera (Lepidoptera: Noctuidae): chemical identification and analysis by electroantennogram.

Our previous results showed that an extract of the abdomens of mated females of the cotton bollworm, Helicoverpa armigera, deterred oviposition of conspecifics. In this paper, we found that the extract, in addition to reducing conspecifics' oviposition, could elicit strong electroantennogram responses from mated females. The EAG elicitors mainly came from mature chorionated eggs in the ovarioles. Laid eggs or their surface extract evoked similar EAG responses. The main chemical components of the EAG elicitors from mature chorionated and laid eggs were myristic, palmitic, stearic, and oleic acids. A blend of authentic fatty acids at the ratio found in the laid eggs and in an amount equivalent to 100 laid eggs mimicked the EAG response and deterring effect. Moreover, these four oviposition-deterring fatty acids and their corresponding methyl esters evoked significantly higher EAG responses from both mated females and males than hexane blank and background. The EAG values differed among the test chemicals and between sexes. These results demonstrate that the four fatty acids from eggs are at least partially responsible for the oviposition-deterring effect of the extract from the abdomens of mated female H. armigera and that the moths may detect these chemicals olfactorily by antennae.