Neuroscience
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The A5 area at the ventrolateral pons contains noradrenergic neurons connected with other medullary areas involved in the cardiorespiratory control. Its contribution to the cardiorespiratory regulation was previously evidenced in anesthetized conditions. In the present study, we investigated the involvement of the A5 noradrenergic neurons to the basal and chemoreflex control of the sympathetic and respiratory activities in unanesthetized conditions. ⋯ In adult rats, lesions of A5 noradrenergic neurons did not modify the reflex cardiorespiratory adjustments to hypoxia (7% O2) and hypercapnia (7% CO2). In the in situ preparations, the sympatho-excitation, but not the PN reflex response, elicited by either the stimulation of peripheral chemoreceptors (ΔtSN: 110±12% vs 58±8%, P<0.01) or hypercapnia (ΔtSN: 9.5±1.4% vs 3.9±1.7%, P<0.05) was attenuated in A5-lesioned rats compared to controls. Our data demonstrated that A5 noradrenergic neurons are part of the circuitry recruited for the processing of sympathetic response to hypoxia and hypercapnia in unanesthetized conditions.
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Wntless (Wls) is implicated in the Wnt signaling pathway by regulating the secretion of Wnt molecules. During brain development, Wls is expressed in the isthmic organizer (ISO) and rhombic lip (RL). Wls regulates Wnt1 secretion at the ISO which is required to induce midbrain-hindbrain structures. ⋯ The Wls-cKO cerebellum also exhibits ectopia of several cell types and aberrations in granule cell organization. Finally, there is a loss of 85% of unipolar brush cells. From these findings, Wls-expressing cells in the rhombic lip are implicated in the orchestration of cerebellar development.
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The classic hypothesis presents the cerebrospinal fluid (CSF) as the "third circulation," which flows from the brain ventricles through the entire CSF system to the cortical subarachnoid space to eventually be passively absorbed into the superior sagittal sinus through arachnoid granulations. The choroid plexus (CP) represents a key organ in the classic CSF physiology and a powerful biological pump, which exclusively secretes CSF. ⋯ The classic hypothesis cannot provide an explanation for these controversies but the recently formulated Bulat-Klarica-Orešković hypothesis can. According to this hypothesis, CSF production and absorption (CSF exchange) are constant and present everywhere in the CSF system, and although the CSF is partially produced by the CP, it is mainly formed as a consequence of water filtration between the capillaries and interstitial fluid.
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Exercise has been proven to promote learning and memory, and is closely related to increased adult neurogenesis in the hippocampus. In our study, the β subunit of Glycogen synthase kinase-3 (GSK3β) can be significantly regulated by exercise, and the modulation of GSK3β activity can enhance adult neurogenesis and memory. To explore the mechanism by which exercise can improve cognitive function and adult neurogenesis, and the role GSK3β plays in this process, we established a mouse model of voluntary exercise to examine the expression and activity of GSK3β, and its associated signaling pathways, in the hippocampus dentate gyrus. ⋯ The activity of the insulin pathway, which negatively regulates GSK3β, was also increased. Moreover, our results showed that the dopamine D1 receptor (DARP D1) pathway and adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) were also activated, which indicates a relationship between GSK3β and neurogenesis. Overall, our findings demonstrated that voluntary exercise promotes cognition and neurogenesis in the adult mouse dentate gyrus by the regulation of GSK3β expression and activity, which may be implemented through the DARP D1 receptor-signaling pathway.
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The septum is an evolutionarily well-conserved part of the limbic system. It is known to be involved in many aspects of social behavior and is considered a key node of the social behavior network, together with the preoptic area. Involvement of these two brain regions has been recently observed in newly hatched chicks exposed to the natural motion of a living conspecific. ⋯ Here we show that the right septum and the preoptic area of newly hatched visually naïve chicks exposed to speed changes have higher neuronal activity (revealed by c-Fos expression), compared with that of chicks exposed to constant motion. We thus found an involvement of these two areas in the perception of motion cues associated with animacy in newly hatched chicks without any previous visual experience. This demonstrates their early involvement in processing simple motion cues that allow the detection of animate creatures and elicit social predispositions in this animal model, as well as preferential attention in human infants and the perception of animacy in human adults.