| 1. |
- Bitaraf, Nazanin, et al.
(författare)
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Development of a multifunctional microfluidic system for studies of nerve cell activity during hypoxic and anoxic conditions
- 2009
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Ingår i: World Congress on Medical Physics and Biomedical Engineering. - Berlin : Springer Science+Business Media B.V.. - 9783642038976 ; , s. 176-179, s. 176-179
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Konferensbidrag (refereegranskat)abstract
- Hemoproteins usually supply cells and tissue with oxygen. A new hemoprotein mainly present in nerve cells called Neuroglobin was recently discovered. Enhanced expression of the protein has been shown to reduce hypoxic neural injury but the mechanism behind this function remains unknown. Methods enabling investigation of the protein in single functional neurons need to be developed. Here, we have studied how the electrical signaling capacity of a neuron was affected by hypoxic environments. Preliminary results show a trend of higher noise-level when a neuron is exposed to hypoxic compared to normoxic surroundings, which implies increased ion-channel activity. The setup used today shows shortages such as reduced control over the oxygen content due to leakage. Therefore, a gas-tight, multifunctional microfluidic system is under development which enables us to study influences of Neuroglobin concentrations on neuronal activity during hypoxia and anoxia. For electrophysiological recordings a patch-clamp micro pipette will be molded into the walls of the microfluidic system. A single biological cell is steered towards the pipette and attached there by means of optical tweezers. The Neuroglobin oxygen binding state will be studied using optical spectroscopy and the neuron environment will be manipulated by applying flows of varying oxygen content through the microfluidic system. This system will constitute a powerful tool in the investigation of the Neuroglobin mechanism of action.
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| 2. |
- Malinina, Evgenya, et al.
(författare)
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Fast neurotransmission in the rat medial preoptic nucleus.
- 2005
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Ingår i: Brain Research. - : Elsevier BV. - 0006-8993. ; 1040:1-2, s. 157-68
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Tidskriftsartikel (refereegranskat)abstract
- The functional properties of neurotransmission in the medial preoptic nucleus (MPN) were studied in a brain slice preparation from young male rats. The aims were to evaluate the thin slice preparation for studying evoked synaptic responses in MPN neurons, to characterize the fast responses triggered by activation of presynaptic nerve fibers in the MPN, and to identify the involved receptor types. Presynaptic stimulation within the MPN evoked postsynaptic voltage and current responses that were blocked by 200 microM Cd2+ or by 2.0 microM tetrodotoxin and were attributed to action potential-evoked transmitter release. The relation to stimulus strength and comparison with spontaneous synaptic currents suggested that in many cases only one presynaptic nerve fiber was excited by the stimulus. Furthermore, the transmission was probabilistic in nature, with frequent failures. Thus, response probability, most likely reflecting transmitter release probability, could be evaluated in the thin slice preparation. Evoked excitatory postsynaptic currents recorded under voltage-clamp conditions were, due to kinetics, I-V relation, and pharmacological properties, attributed to AMPA/kainate receptors and NMDA receptors, whereas inhibitory currents were attributed to GABAA receptors. No responses that could be attributed to glycine or other types of primary transmitters were detected. Although serotonin (5-HT) did not appear to function as a primary transmitter, glutamate- as well as GABA-mediated transmission was suppressed by 500 microM 5-HT, with a clear reduction in response probability observed. 5-HT also reduced the frequency, but not the amplitude, of spontaneous postsynaptic currents and was therefore ascribed a presynaptic site of action.
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| 3. |
- Malinina, Evgenya, et al.
(författare)
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Short-term plasticity in excitatory synapses of the rat medial preoptic nucleus.
- 2006
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Ingår i: Brain Research. - : Elsevier BV. - 0006-8993. ; 1110:1, s. 128-35
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Tidskriftsartikel (refereegranskat)abstract
- The medial preoptic nucleus (MPN) regulates sexual behavior which is subject to experience-dependent modifications. Such modifications must depend on functional plasticity in the controlling neural circuits. Thus, MPN synapses are likely candidates for the site of alterations. The present work is a first systematic study of functional synaptic plasticity at glutamatergic synapses in the MPN. Short-term activity-dependent plasticity was investigated using a slice preparation from young male rats. The average efficacy of AMPA/kainate-receptor-mediated synaptic transmission was activity-dependent, showing a peak at a steady stimulation rate of 2 Hz. The variation in efficacy was attributed to mainly presynaptic factors since the average response amplitude was roughly paralleled by the response probability. Upon paired-pulse stimulation, paired-pulse facilitation as well as paired-pulse depression was observed. In some cases, paired-pulse facilitation as well as paired-pulse depression was recorded from an individual neuron depending on the interval between the paired stimuli. On average, paired-pulse facilitation was observed at intervals <500 ms, and paired-pulse depression at intervals in the range 1-4 s. The findings thus reveal complex activity-dependent short-term plasticity of the functional synaptic properties in the medial preoptic nucleus.
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