Neuroscience
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This study aimed to test the hypothesis that, during extended wakefulness, parasympathetic activity is associated with the depth of the subsequent recovery sleep in mice. Fourteen male C57BL/6 mice were implanted with electrodes for sleep recording. Continuous spectral analysis was performed on the electroencephalogram (EEG) to obtain theta power (6-9Hz) and delta power (0-4Hz), as well as the R-R interval signals in order to quantify the high-frequency power (HF) and normalized low-frequency power (LF%) that are used to assess parasympathetic and sympathetic activity, respectively. ⋯ Both the rise in HF and theta power during extended wakefulness were found to be positively correlated with the delta power rebound. Furthermore, the HF change during extended wakefulness was also correlated with the amount of sleep loss and the enhancement of waking theta power. Our finding suggests that waking parasympathetic activity intimately reflects the cumulative sleep pressure, suggesting a potential role to be an autonomic marker for sleep propensity.
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Responses to personal space (PS) violations are variable and depend (besides many other factors) on the sex of the person who enters this space. The neuronal basis of this effect is still largely unknown. A previous neuroimaging investigation had shown that male participants responded with increased amygdala activation to PS violation, but only when the intruder was male. ⋯ When the approaching person was male additional amygdala activation was detected. Because the amygdala is a central structure for the initiation of defense responses, the heightened activation might reflect that male intrusion was decoded as potential threat. Hence, we observed a similar gender bias to simulated space intrusion in women as previously in men.
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Hypoglycemia is defined by an arbitrary plasma glucose level lower than 3.9mmol/L and is a most common and feared adverse effect of treatment of diabetes mellitus. Emerging evidences demonstrated that hypoglycemia could induce enhanced apoptosis. Lithium chloride (LiCl), a FDA approved drug clinically used for treatment of bipolar disorders, is recently proven having neuroprotection against various stresses in the cellular and animal models of neural disorders. ⋯ Hypoglycemia-induced apoptosis were significantly reversed by LiCl, leading to increased cell survival. LiCl also alters the expression/levels of the Wnt pathway genes/proteins, which were reduced due to exposed to hypoglycemia. Overall, our results conclude that LiCl provides neuroprotection against hypoglycemia-induced apoptosis via activation of the canonical Wnt signaling pathway.
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AMP-activated protein kinase (AMPK) is a master enzyme that regulates ATP-sensitive K(+) (K-ATP) channels in pancreatic beta-cells and cardiac myocytes. We used patch pipettes to record currents and potentials to investigate effects of AMPK on K-ATP currents in substantia nigra compacta (SNC) dopamine neurons in slices of rat midbrain. When slices were superfused repeatedly with the K-ATP channel opener diazoxide, we were surprised to find that diazoxide currents gradually increased in magnitude, reaching 300% of the control value 60min after starting whole-cell recording. ⋯ However, superfusion with A769662 significantly augmented the inhibitory effect of diazoxide on firing rate. We conclude that K-ATP channel function is augmented by AMPK, which is activated during the process of making whole-cell recordings. Our results suggest that AMPK and K-ATP interactions may play an important role in regulating dopamine neuronal excitability.
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The use of more ethological animal models to study the neurobiology of anxiety has increased in recent years. We assessed the effect of an environmental enrichment (EE) protocol (24h/day over a period of two months) on anxiety-related behaviors when aged Wistar rats (21months old) were confronted with cat odor stimuli. Owing to the relationship between GABAergic interneurons and the anxiety-related neuronal network, we examined changes in the expression of Parvalbumin (PV) and 67kDa form of glutamic acid decarboxylase (GAD-67) immunoreactive cells in different brain regions involved in stress response. ⋯ Regarding the neurobiological data, the EE increased the expression of PV-positive cells in some medial prefrontal regions (cingulate (Cg) and prelimbic (PL) cortices), whereas the GAD-67 expression in the basolateral amygdala was reduced in the enriched group. Our results suggest that EE is able to reduce anxiety-like behaviors in aged animals even when ethologically relevant stimuli are used. Moreover, GABAergic interneurons could be involved in mediating this resilient behavior.