Calcium oscillations in rhythmically active respiratory neurones in the brainstem of the mouse

The rhythmically active respiratory network in the brainstem slice of the mouse was investigated under in vitro conditions using patch clamp and microfluorometric techniques. Rhythmic respiratory activity persisted over the whole course of an experiment.Electrophysiologically recorded rhythmic activity in respiratory neurones was accompanied by oscillations in intracellular calcium, which displayed a maximal concentration of 300 nm and decayed to basal levels with a mean time constant of 1.6 ± 0.9 s.Elevations of calcium concentrations were highly correlated with the amplitude of rhythmic membrane depolarization of neurones, indicating that they were initiated by a calcium influx across the plasma membrane through voltage-gated calcium channels.Voltage clamp protocols activating either high voltage-activated (HVA) or both HVA and low voltage-activated (LVA) calcium channels showed that intracellular calcium responses were mainly evoked by calcium currents through HVA channels.Somatic calcium signals depended linearly on transmembrane calcium fluxes, suggesting that calcium-induced calcium release did not substantially contribute to the response.For calcium elevations below 1 μm, decay time constants were essentially independent of the amplitude of calcium rises, indicating that calcium extrusion was adequately approximated by a linear extrusion mechanism.Cytosolic calcium oscillations observed in neurones of the ventral respiratory group provide further evidence for rhythmic activation of calcium-dependent conductances or second messenger systems participating in the generation and modulation of rhythmic activity in the central nervous system

Expression of 15 glutamate receptor subunits and various splice variants in tissue slices and single neurons of brainstem nuclei and potential functional implications

Brainstem nuclei serve a diverse array of functions in many of which ionotropic glutamate receptors are known to be involved. However, little detailed information is available on the expression of different glutamate receptor subunits in specific nuclei. We used RT-PCR in mice to analyze the glutamate receptor subunit composition of the pre-Botzinger complex, the hypoglossal nucleus, the nucleus of the solitary tract, and the inferior olive. Analyzing 15 receptor subunits and five variants, we found all four alpha-amino-3-hydroxy-5-methyl-4-propionic acid (AMPA) and six NMDA receptor (NR) subunits as well as three of five kainate (KA) receptors (GluR5, GluR6, and KA1) to be expressed in all nuclei. However, some distinct differences were observed: The inferior olive preferentially expresses flop variants of AMPA receptors, GluR7 is more abundant in the pre-Botzinger complex than in the other nuclei, and NR2C is most prominent in the nucleus of the solitary tract. In single hypoglossal motoneurons and interneurons of the pre-Botzinger complex investigation of GluR2 editing revealed strong expression of the GluR2-R editing variant, suggesting tow Ca2+ permeability of AMPA receptors. Thus, Ca2+-permeable AMPA receptors are unlikely to be the cause for the reported selective vulnerability of hypoglossal motoneurons during excitotoxic events

2023 State of the Future of Work

The 2023 State of the Future of Work Report is the first report from the Work Futures Hallmark Research Initiative (WFHRI), a team of interdisciplinary researchers from The University of Melbourne. Drawing on data on the work experiences of 1,400 Australian workers since the pandemic, we identify four critical future of work themes: 1. Unsafe: Australians feel their work and workplaces are unsafe, sites of discrimination for women, Aboriginal and Torres Strait Islanders, caregivers and people living with chronic illnesses. 2. Unwell: Work, as it currently stands, is making many Australians unwell, with many working harder and reporting greater exhaustion than prepandemic, especially those in their prime working ages. 3. Uncertain: Australian workers have a limited understanding of how the upcoming technological changes driven by automation and artificial intelligence will impact their jobs, creating greater uncertainty. Work, as it currently stands, is rapidly changing, with many Australians unclear on how to keep up. 4. Opportunity: Despite these massive issues, Australian workers see greater opportunity to support workers to build happier, more satisfied work lives especially through the rise of flexible workplaces and flexible work practices

Kinetics and subunit composition of NMDA receptors in respiratory-related neurons

NMDA receptors are involved in a variety of brainstem functions. The excitatory postsynaptic NMDA currents of pre-Botzinger complex interneurons and hypoglossal motoneurons, which are located in the medulla oblongata, show remarkably fast deactivation kinetics of approximately 30 ms compared with NMDA receptors in other types of neurons. Because structural heterogeneity might be the basis for physiological properties, we examined the expression of six NMDA receptor subunits (NMDAR1, NR2A-2D, and NR3A) plus eight NMDR1 splice variants in pre-Botzinger complex, hypoglossal and, for comparison, neurons from the nucleus of the solitary tract in young rats using single cell multiplex RT-PCR. Expression of NR2A, NR2B, and NR2D was observed in all three cell types while NR3A was much more abundant in pre-Botzinger complex interneurons, which belong to the rhythm generator of respiratory activity. In hypoglossal neurons, the NMDAR1 splice variants NMDAR1-4a and NMDAR1-4b were found. In neurons of the nucleus of the solitary tract, instead of NMDAR1-4b, the NMDAR1-2a splice variant was detected. This differential expression of modulatory splice variants might be the molecular basis for the characteristic functional properties of NMDA receptors, as neurons expressing a special NMDAR1 splice variant at the mRNA level show fast kinetics compared with neurons lacking this splice variant