Inputs from three brainstem sources to identified neurons of the mouse inferior colliculus slice.

A total of 40 neurons from of the central nucleus of the mouse inferior colliculus (IC) were recorded intracellularly from brain slices to determine input properties by electrical stimulation of the ipsilateral lateral lemniscus (LL), commissure of Probst (CP), and commissure of the IC (CoIC) together with cellular morphology (in 25 neurons) by biocytin injection and staining. Nine neurons had oriented (bipolar), 16 neurons non-oriented (multipolar) dendritic trees of various sizes. Axon collaterals of a given neuron often ran in several directions to provide multiple input to adjacent isofrequency laminae, the lateral nucleus of the IC, the brachium of the IC, the LL, the CP, and the IC commissure. Neurons were classified by spike response patterns to depolarizing current injection into onset- and sustained-spiking cells. The former had significantly shorter membrane-time constants, significantly less frequently and smaller hyperpolarizations after spike occurrence, and more Ca2+-humps. These properties and their preferred position in the dorsolateral ICC suggest a participation in binaural temporal processing. Almost all oriented cells showed only excitatory post-synaptic potentials (EPSPs) after LL stimulation, while in non-oriented cells inhibitory post-synaptic potentials (IPSPs) after the EPSPs were significantly more frequent. Neurons with largest dendritic trees and many dorsalward projecting axon collaterals were found in the ventral IC. There, neurons had average 4 ms (two synapses) shorter response latencies to LL stimulation than dorsally located neurons. Thus, neurons in the central and dorsal IC may receive mono- and disynaptic input from ventrally located neurons.

ATP-induced oscillations of cytosolic Ca2+ activity in cultured astrocytes from rat brain are modulated by medium osmolarity indicating a control of [Ca2+]i oscillations by cell volume.

Oscillations of cytosolic Ca2+ activity ([Ca2+]i) induced by stimulation with ATP in rat astrocytes in primary cultures were analysed. Astrocytes, prepared from the brains of newborn rats, loaded with the fluorescent Ca2+ indicator fura-2/AM, were continuously stimulated with ATP (10 microM). ATP caused a large initial [Ca2+]i peak, followed by regular [Ca2+]i oscillations (frequencies 1-5/min). Astrocytes were identified by glial fibrillary acidic protein staining of cells after [Ca2+]i recording. The oscillations were reversibly blocked by the P2 purinoceptor antagonist suramin (30 microM). Influx of extracellular Ca2+ and mobilization of Ca2+ from intracellular stores both contributed to the oscillations. The effects of hypertonic and hypotonic superfusion medium on ATP-induced [Ca2+]i oscillations were examined. Hypertonic medium (430 mOsm) reversibly suppressed the ATP-induced oscillations. Hypotonic medium (250 mOsm), in spite of having heterogeneous effects, most frequently induced a rise in [Ca2+]i or reversibly increased the frequency of the oscillations. Thus, a change in cell volume might be closely connected with [Ca2+]i oscillations in astrocytes indicating that [Ca2+]i oscillations in glial cells play an important role in regulatory volume regulation in the brain.

[Ca2+]i oscillations induced by bradykinin in rat glioma cells associated with Ca2+ store-dependent Ca2+ influx are controlled by cell volume and by membrane potential.

Long-term superfusion with bradykinin causes oscillations of cytosolic Ca2+ activity ([Ca2+]i) in Fura-2 loaded rat glioma cells. The [Ca2+]i rise is associated with synchronous plasma membrane hyperpolarization oscillating with a frequency of 0.8-1.8 per min. The initial large transient [Ca2+]i rise, induced immediately with bradykinin admission results from InsP3-mediated Ca2+ release, whereas the subsequent oscillations depend mainly on Ca2+ influx, as demonstrated: (i) by blockade of [Ca2+]i oscillations by reduction of [Ca2+]ex' or addition of Ca(2+)-channel blockers; and (ii) evidence from Mn2+ quench experiments. Suppression of [Ca2+]i oscillations with high K+ depolarization and with block of Ca(2+)-dependent K+ channels proves that membrane hyperpolarization is required for Ca2+ influx during the oscillation. Ca2+ release from intracellular stores by inhibitors of endoplasmic reticulum Ca(2+)-ATPase attenuates or blocks the [Ca2+]i oscillations. This suggests that bradykinin-induced Ca2+ influx is controlled by the filling state of the stores. The [Ca2+]i oscillations are suppressed by hypertonic medium and enhanced by hypotonic medium. Cell swelling enhances Ca2+ influx. We propose the following model for generation of the oscillations in the glial cell line: InsP3-induced Ca2+ release from internal stores periodically evokes Ca2+ influx through Ca(2+)-permeable cation channels. Hyperpolarization of the plasma membrane due to the activation of Ca(2+)-dependent K+ channels enhances the Ca2+ influx. The concomitant K+ efflux could lead to cell shrinkage which suppresses Ca2+ influx. Cell volume and membrane potential probably serve as feedback regulators during the [Ca2+]i oscillations.

Cross-talk of the receptors for bradykinin, serotonin, and ATP shown by single cell Ca2+ responses indicating different modes of Ca2+ activation in a neuroblastoma x glioma hybrid cell line.

Modes of Ca2+ activation by bradykinin, serotonin, and ATP and the possible receptor cross-talk were investigated in mouse neuroblastoma x rat glioma hybrid cells (108CC15) by monitoring fura-2 fluorescence in single cells. A transient rise of cytosolic Ca2+ activity was induced by short pulses of the hormones. Brief exposure of cells to ionomycin, which depletes intracellular Ca2+ stores, reduced the size of subsequent responses to bradykinin or ATP, but not to serotonin. Superfusion of the cells with Ca(2+)-free medium abolished the Ca2+ response to serotonin, whereas the responses to bradykinin and to ATP were only slightly reduced. This indicates that ATP, like bradykinin, induces the release of Ca2+ from intracellular stores. Serotonin, in contrast, activates Ca2+ entry from the extracellular space. To investigate whether ATP releases Ca2+ from the same stores as bradykinin, we examined the interaction of the hormones by applying them consecutively. When ATP was applied after bradykinin, the nucleotide did not evoke any response, irrespective of the presence or absence of extracellular Ca2+. The application of ATP before that of bradykinin reduced the size of a following bradykinin-induced Ca2+ response in Ca(2+)-free medium, but not in Ca(2+)-containing medium. This suggests that bradykinin may interact with the ATP-activated mechanism by cross-desensitization. Possibly, bradykinin receptors are coupled to additional Ca2+ stores not accessible to ATP that are refilled by extracellular Ca2+. Cyclic AMP and cyclic GMP apparently do not affect the Ca2+ responses to bradykinin and serotonin, as shown by the lack of influence of preincubation of the cells with forskolin or sodium nitroprusside.

[Aerosol immunization of ducks with Spirovak erysipelas vaccine "Dessau"]. / Die Aerosolimmunisierung von Enten mit Spirovak-Rotlauf-Impfstoff "Dessau".

A method for active immunisation of ducklings during the raising period (between the first and 20th days of age) was devised in another attempt to control erysipelas septicaemia of duck on freeland fattening sites. Spirovak erysipelas vaccine "Dessau" was aerogenically applied through vortex injector nozzles, when the animals were between five and 20 days of age. Immunisation took place in groups of 5,000 animals each. The vaccine concentrations were four doses per cubic metre in the first immunisation and eight doses per cubic metre in the second. Exposures were 30 minutes in the first immunisation and 20 minutes in the second. Ten man-hours were required to immunise 10,000 ducks. Benefits of the method are substantive improvement of working conditions, higher labour productivity, and lower production cost.