Cardioprotective effect of Danshen injectable powder on pressure overload-induced ventricular remodeling in rats and isoproterenol induced myocardial injury in mice / 中国药理学与毒理学杂志

OBJECTIVE To determine the effects of Danshen injectable powder on myocardial remodeling in pressure overload rats and isoproterenol(ISO)injection mice.METHODS SD Rats were subject to abdominal aortic constriction(AAC)surgery to develop pressure overload.Therapeutic effect of Danshen injectable powder was assessed six weeks after AAC surgery. The lactic dehydrogenase (LDH) and creatine kinase (CK) levels in serum, biometric, echocardiographic parameters, interstitial fibrosis, the expression of DJ-1 and SOD2 were then measured. The myocardial impairment in mice was induced by ISO injection. LDH and CK in serum, biometric, interstitial fibrosis were measured to investigate the cardioprotective effect of Danshen injectable powder. Matrix-assisted laser desorption mass spectrometry imaging(MALDI-MSI)was used to detect the changes of 60-1000 Da molecules in mice heart tissue. RESULTS In AAC rats, we observed compensatory hypertrophy and perivascular fibrosis,however cardiac function had not progressed to deterioration.The levels of LDH and CK were decreased significantly in the Danshen injectable powder groups(P<0.05,P<0.05).Danshen injectable powder could alleviate the perivascular collagen deposits but not cardiac hypertrophy in AAC rats. Furthermore,Danshen injectable powder enhanced the expression levels of SOD2 and DJ-1 in cardio-myocytes (P<0.05, P<0.01). In ISO injection mice, the levels of HWI and LDH were decreased signifi-cantly in drug treatment group compared with model group (P<0.01, P<0.01). In the MALDI-MSI of mice heart section,Danshen injectable powder can improve the reduction of energy metabolism-related substances including adenosine, creatine and ADP induced by ISO impairment. CONCLUSION Danshen injectable powder can attenuate perivascular fibrosis and improve the expression of anti-oxidative stress-related proteins SOD2,DJ-1 in the rats with pressure overload-induced left ventricular remodeling.Danshen injectable powder has cardioprotective effect on ISO impairment in mice which is probably related to improvement of energy metabolism.

Multi-channel in vivo recording techniques: signal processing of action potentials and local field potentials / 生理学报

Multi-channel in vivo recording techniques are used to record ensemble neuronal activity and local field potentials (LFP) simultaneously. One of the key points for the technique is how to process these two sets of recorded neural signals properly so that data accuracy can be assured. We intend to introduce data processing approaches for action potentials and LFP based on the original data collected through multi-channel recording system. Action potential signals are high-frequency signals, hence high sampling rate of 40 kHz is normally chosen for recording. Based on waveforms of extracellularly recorded action potentials, tetrode technology combining principal component analysis can be used to discriminate neuronal spiking signals from differently spatially distributed neurons, in order to obtain accurate single neuron spiking activity. LFPs are low-frequency signals (lower than 300 Hz), hence the sampling rate of 1 kHz is used for LFPs. Digital filtering is required for LFP analysis to isolate different frequency oscillations including theta oscillation (4-12 Hz), which is dominant in active exploration and rapid-eye-movement (REM) sleep, gamma oscillation (30-80 Hz), which is accompanied by theta oscillation during cognitive processing, and high frequency ripple oscillation (100-250 Hz) in awake immobility and slow wave sleep (SWS) state in rodent hippocampus. For the obtained signals, common data post-processing methods include inter-spike interval analysis, spike auto-correlation analysis, spike cross-correlation analysis, power spectral density analysis, and spectrogram analysis.

Multi-channel in vivo recording techniques: analysis of phase coupling between spikes and rhythmic oscillations of local field potentials / 生理学报

The purpose of this article is to introduce the measurements of phase coupling between spikes and rhythmic oscillations of local field potentials (LFPs). Multi-channel in vivo recording techniques allow us to record ensemble neuronal activity and LFPs simultaneously from the same sites in the brain. Neuronal activity is generally characterized by temporal spike sequences, while LFPs contain oscillatory rhythms in different frequency ranges. Phase coupling analysis can reveal the temporal relationships between neuronal firing and LFP rhythms. As the first step, the instantaneous phase of LFP rhythms can be calculated using Hilbert transform, and then for each time-stamped spike occurred during an oscillatory epoch, we marked instantaneous phase of the LFP at that time stamp. Finally, the phase relationships between the neuronal firing and LFP rhythms were determined by examining the distribution of the firing phase. Phase-locked spikes are revealed by the non-random distribution of spike phase. Theta phase precession is a unique phase relationship between neuronal firing and LFPs, which is one of the basic features of hippocampal place cells. Place cells show rhythmic burst firing following theta oscillation within a place field. And phase precession refers to that rhythmic burst firing shifted in a systematic way during traversal of the field, moving progressively forward on each theta cycle. This relation between phase and position can be described by a linear model, and phase precession is commonly quantified with a circular-linear coefficient. Phase coupling analysis helps us to better understand the temporal information coding between neuronal firing and LFPs.