Neuroscience
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The cellular mechanisms by which LC neurons respond to hypercapnia are usually attributed to an "accelerator" whereby hypercapnic acidosis causes an inhibition of K+ channels or activation of Na+ and Ca+2 channels to depolarize CO2-sensitive neurons. Nevertheless, it is still unknown if this "accelerator" mechanism could be controlled by a brake phenomenon. Whole-cell patch clamping, fluorescence imaging microscopy and plethysmography were used to study the chemosensitive response of the LC neurons. ⋯ Inhibition of BK channels in LC neurons by bilateral injections of paxilline into the LC results in a significant increase in the hypercapnic ventilatory response of adult rats. Our findings indicate that a BK channel-based braking system helps to determine the chemosensitive respiratory drive of LC neurons and contributes to the hypercapnic ventilatory response. Perhaps, abnormalities of this braking system could result in hypercapnia-induced respiratory disorders and panic responses.
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Type 2 diabetes mellitus (T2DM)-associated oxidative stress contributes to cognitive deficiencies and Alzheimer's disease (AD). Sulforaphane (SFN) is a pharmacological activator of Nrf2 that provokes Nrf2-mediated intracellular defenses, including antioxidant and anti-inflammatory responses, under oxidative stress (OS) conditions. This study investigated the effects of SFN on DM-related cognitive decline and its potential mechanisms. ⋯ Accordingly, immunoblotting and immunohistochemistry analyses showed that SFN decreased the levels of amyloid-β (Aβ) oligomers and Aβ 1-42 plaques as well as phospho-tau at Ser396 and Thr231 in the DM mouse hippocampus. This protective effect of SFN might be due to the activation of Nrf2-regulated antioxidant defense deficiencies in the DM mice, as SFN increased the Nrf2 nuclear accumulation and the downstream expression of the antioxidases HO-1 and NQO1 and reduced the levels of the reactive oxygen/nitrogen species (ROS/RNS) in DM mouse brains. Our results confirm that SFN has potential as a therapeutic agent to protect T2DM patients from cognitive deficiencies and AD-like pathological lesions related to the upregulation of Nrf2-regulated antioxidant defenses.
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Focal administration of pharmacological agents during in vivo recordings is a useful technique to study the functional properties of neural microcircuits. However, the lack of visual control makes this task difficult and inaccurate, especially when targeting small and deep regions where spillover to neighboring regions is likely to occur. An additional problem with recording stability arises when combining focal drug administration with in vivo intracellular recordings, which are highly sensitive to mechanical vibrations. ⋯ We applied tetrodotoxin (TTX 10 µM) during whole-cell recordings in the striatum, while simultaneously obtaining extracellular recordings in S1 and M1. The focal application of TTX in the striatum blocked Up states in the recorded striatal neurons, without affecting the cortical activity. We also describe two different approaches for precisely releasing the drugs without unwanted leakage along the pipette approach trajectory.
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Adolescence is a sensitive and critical period in brain development where psychiatric disorders such as anxiety, depression and post-traumatic stress disorder are more likely to emerge following a stressful life event. Females are two times more likely to suffer from psychiatric disorders than males. Patients with these disorders show alterations in orexins (also called hypocretins), important neuropeptides that regulate arousal, wakefulness and the hypothalamic-pituitary-adrenal axis activity. ⋯ In contrast to adolescent males, adult males in the 10 mg/kg dose group showed the opposite effect on immobility compared to vehicle. These results indicate that 10 mg/kg dose of SB334867 has opposing effects in adolescent and adult males, but few effects in adolescent and adult females. Differences in functional networks between limbic regions may underlie these effects of orexin receptor blockade that are sex- and age-dependent in rats.