A blunted sympathetic and accentuated parasympathetic response to postural change in subjects with depressive disorders.

BACKGROUND: In recent years, the bi-directional relationship between depression and ANS dysfunction has received considerable attention, but findings remain inconclusive. In this study, we aimed to examine the spectral HRV response to postural change in subjects with depressive disorders and in healthy controls, in order to gain insight into the characteristics of autonomic nervous system (ANS) response to postural change in subjects with depressive disorders. METHODS: We compared HRV response to postural change between subjects with depressive disorders and healthy controls aged 20-37 years. Depression severity was assessed by the self-reported Beck Depression Inventory-II (BDI-II). Spectral HRV was analyzed at two moments: 10 min seated rest and 10 min at standing position, with spontaneous breathing. RESULTS: No significant differences existed in the resting spectral HRV indices between subjects with depressive disorders and controls, however, following postural change, the increasing level of LF and LF/HF was lower and the decreasing level of HF power was higher, in the individuals with depression than that in healthy subjects. The differences in the LF power, HF power and the LF/HF ratio between seated rest before standing up and after postural change were found negatively correlated with depression severity. CONCLUSION: We found a blunted sympathetic and accentuated parasympathetic response to postural change in subjects with depressive disorder, suggesting that the autonomic impairment and early ANS dysfunction may exist among depressed individuals. These findings indicated that spectral analysis of HRV associated with postural change may be a more sensitive method than resting HRV analysis for detecting ANS dysfunction in depressive disorders. LIMITATIONS: Further studies are needed to expand the sample size and to clarify the mechanisms responsible for the autonomic dysfunction observed in individuals with depressive disorders.

Attenuated or absent HRV response to postural change in subjects with primary insomnia.

Previous studies have compared rest heart rate variability (HRV) between insomniacs and good sleepers, but the results have not been consistent. The altered HRV behavior in response to postural change was considered useful as another sensitive measure for evaluating the autonomic nervous function, however, to our knowledge, no study was found using HRV response to postural change in primary insomnia. Our study aimed to examine HRV response to postural change maneuver (PCM) in both primary insomniacs and controls between 22 and 39 years of age to gain insights into the characteristics of the autonomic nervous system (ANS) function in primary insomnia subjects. HRV was recorded for 5 min at seated rest, and then, the subjects quickly stood up from a seated position in up to 3s and remained standing for 15 min. HRV was recorded at the following times: seated rest and 0-5 min, 5-10 min and 10-15 min in the standing position. In primary insomnia subjects, attenuated or absent HRV response to postural change was identified, the increase in LF/HF ratio and the decrease in HF and SD1 from seated to standing were much slower than in the normal controls. In conclusion, this study provided evidence of the possible bi-directional relationship between insomnia and autonomic nervous system (ANS) function, which will move us closer to developing a new sensitive method for measuring autonomic impairment and early sympathetic damage in primary insomnia subjects.

Case-control study on the association between qi-stagnation and insomnia.

OBJECTIVE: To investigate the relationship between insomnia and qi-stagnation by using the international standardized measurement of sleep quality and the Traditional Chinese Medicine (TCM) Constitution Scales. METHODS: A survey by means of the TCM Constitution Scales, the Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS) and the Deep Sleep Scale (DSS) in 169 participants aged between 16 and 80 years old was conducted. Comparison was made to examine the sleep quality and insomnia symptoms in the qi-stagnation group and other-constitution group. RESULTS: Univariate analysis found that the qi-stagnation group had a significantly increased risk of difficulty in falling asleep (OR=3.012, and 95% CI 1.310 to 6.923 for PSQI; OR=3.016, and 95% CI 1.358 to 6.709 for DSS) and early waking (OR=3.545, and 95% CI 1.229 to 10.232 for PSQI; OR=2.742, and 95% CI 1.072 to 7.014 for DSS), while the other-constitution group had a significant risk of dreaminess (OR=2.419, and 95% CI 1.154 to 5.072 for PSQI; OR=2.561, and 95% CI 1.116 to 5.880 for DSS). A dose-effect relationship existed between insomnia symptoms and qi-stagnation. Qi-stagnation significantly increased the risk of difficulty in falling asleep and early waking. CONCLUSION: This case-control study revealed that there is a statistically significant association between qi-stagnation and insomnia. Based on this study, we recommend that further research should be conducted for the rehabilitative care and cure of insomnia from the perspective of TCM constitution.

[Monitoring of anesthetic effect based on auditory response time].

OBJECTIVE: To investigate the changes of auditory parameters during anesthesia and establish the assessment indicators for anesthesia monitoring in animal experiments. METHODS: BALB/c mice of 4 to 6 weeks were given a single intraperitoneal dose of urethane, and the auditory evoked potential in the surgically exposed inferior colliculus in response to pure tone stimulation was recorded during urethane metabolism. The latency and amplitude data of the waves were extracted using Matlab software to analyze their variations during urethane metabolism. RESULTS: The latency of the auditory evoked potential showed slight variation and was well correlated to time. The latency decreased progressively during urethane metabolism, fast in the initial 2 h and tending to stabilize afterwards. CONCLUSION: The latency of the auditory evoked potential can be more suitable indicators than the amplitude for anesthetic effect monitoring.

[Response properties of cochlear nucleus neurons: a digital model-based study].

OBJECTIVE: To investigate the mechanisms of different response patterns of the cochlear nucleus neurons based on a digital model. METHODS: Based on the platform of Matlab7.0 and the integrate-and-fire model, we constructed the temporal coding model. RESULTS: The model well simulated the response types of the primary-like, chopper, onset and buildup neurons by changing the settings of some parameters related to the properties of the neurons. CONCLUSIONS: The properties of the neurons dictate the response patterns of the cochlear nucleus neurons. The simulation results are consistent with the literature. Understanding of the response properties of the cochlear nucleus neurons can provide assistance in the study of the auditory system.

[Effect of bicuculline on first spike latency of the neurons in the inferior colliculus of mice].

OBJECTIVE: To evaluate the effect of bicuculline on the first spike latency of the neurons in the inferior colliculus of mice and investigate the role of GABA inhibition in sound signal processing of the neurons. METHODS: In vivo extracellular recording was performed on the inferior colliculus of 13 BALB/c mice (4 to 5 weeks old) to record the neuronal response to pure tones. Bicuculline, a GABA-A receptor antagonist, was applied to the neurons iontophoretically through one channel in the three-barrel glass-pipettes. The first spike latency and other response properties of the characteristic frequency were recorded for analysis. RESULTS: A total of 30 well-isolated single neurons were recorded. Increased spike counts characterized 96% of the neurons, with either increased (40%) or decreased (60%) latency of neuronal responses. Characteristic frequency alterations occurred in 50% of the neurons with increased spike latency, and the minimum threshold showed linear changes. CONCLUSION: GABAergic inhibition may participate in the latency formation and increased frequency selectivity of mouse inferior colliculus neurons by lateral inhibition. The changes in the first spike latency can be indicative of the information integration in GABAergic neurons at the synaptic level.

Delayed inhibition creates amplitude tuning of mouse inferior collicular neurons.

Nonmonotonic intensity response neurons referred as amplitude-tuned neurons are considered to be created by high-threshold inhibition in auditory system. Very limited information, however, is available on how the inhibition works for amplitude-tuned neurons. We studied the temporal response properties of these neurons with or without iontophoresis of bicuculline (gamma-aminobutyric acid A antagonist). In most neurons, the firing durations gradually reduced with the increasing amplitudes beyond the best amplitudes. Bicuculline application selectively blocked the inhibition of the sustained responses to high amplitudes and abolished the nonmonotonic intensity response properties. Our results suggest that a temporally delayed inhibition, whose latency reduced related to excitation with the increasing amplitude, is responsible for the creation of about 71% amplitude-tuned neurons in mouse inferior colliculus.

Neuroprotective effects of Buyang Huanwu Decoction on neuronal injury in hippocampus after transient forebrain ischemia in rats.

Buyang Huanwu Decoction (BYHWD), a traditional Chinese medicine, has been developed as a drug to be used for treatment of stroke for hundreds of years. However, the underlying mechanisms remain unknown. In the present study, the effects of BYHWD on delayed neuronal death of hippocampus after transient forebrain ischemia were examined in rats. Transient forebrain ischemia in a duration of 15 min was induced with the four-vessel occlusion method. BYHWD (per 6.65 g/kg) was given orally to rats twice each day for 7 days before ischemia. In BYHWD-pretreated rats, the neuronal injury in the hippocampal CA1 region was significantly less than that of controls. Oral administration of BYHWD also markedly attenuated the number of TUNEL-positive neurons and suppressed the expression of caspase-3p20, a product of catalytically active caspase-3, in the CA1 region. Our results suggest that an inhibition of caspase-3 and apoptosis by BYHWD may partially account for its neuroprotection against ischemic injury in the hippocampal CA1 region.