25th annual computational neuroscience meeting: CNS-2016

The same neuron may play different functional roles in the neural circuits to which it belongs. For example, neurons in the Tritonia pedal ganglia may participate in variable phases of the swim motor rhythms [1]. While such neuronal functional variability is likely to play a major role the delivery of the functionality of neural systems, it is difficult to study it in most nervous systems. We work on the pyloric rhythm network of the crustacean stomatogastric ganglion (STG) [2]. Typically network models of the STG treat neurons of the same functional type as a single model neuron (e.g. PD neurons), assuming the same conductance parameters for these neurons and implying their synchronous firing [3, 4]. However, simultaneous recording of PD neurons shows differences between the timings of spikes of these neurons. This may indicate functional variability of these neurons. Here we modelled separately the two PD neurons of the STG in a multi-neuron model of the pyloric network. Our neuron models comply with known correlations between conductance parameters of ionic currents. Our results reproduce the experimental finding of increasing spike time distance between spikes originating from the two model PD neurons during their synchronised burst phase. The PD neuron with the larger calcium conductance generates its spikes before the other PD neuron. Larger potassium conductance values in the follower neuron imply longer delays between spikes, see Fig. 17.Neuromodulators change the conductance parameters of neurons and maintain the ratios of these parameters [5]. Our results show that such changes may shift the individual contribution of two PD neurons to the PD-phase of the pyloric rhythm altering their functionality within this rhythm. Our work paves the way towards an accessible experimental and computational framework for the analysis of the mechanisms and impact of functional variability of neurons within the neural circuits to which they belong

EFFECTS OF CALCIUM ADMINISTRATION ON PARATHYROID GLAND, NaPi 2a COTRANSPORTER AND PTH1R IN AN ANIMAL MODEL OF THE ANDROPAUSE EFEKTI TRETMANA KALCIJUMOM NA PARATIREOIDNU @LEZDU, NaPi 2a KOTRANSPORTER I PTH1R U ANIMALNOM MODELU ANDROPAUZE

Summary Background: Increased risk of osteoporotic bone fractures represents the adverse event in andropausal men. Due to diminished calcium absorption in elderly, its supplementation is used for prevention and treatment of advanced-age osteoporosis. Methods: Sixteen-month-old Wistar rats were divided into sham-operated (SO), orchidectomized (Orx) and Ca 2+ -treated orchidectomized (Orx+Ca) groups. Ca 2+ (28.55 mg/kg b.w.) was administered intramuscularly for 3 weeks, while the SO and Orx received vehicle alone. Parathyroid glands (PTG) were analyzed histomorphometrically, while the expression of NaPi 2a mRNA from kidneys was determined by real time PCR. NaPi 2a and PTH1R abundance was detected immunofluorescently. Serum and urine parameters were determined biochemically. Results: The PTG volume was 15% (p<0.05) greater in Orx rats than in the SO group. In Orx+Ca 2+ animals, PTG volume was decreased by 17% (p<0.05), when compared to the Orx rats. Orchidectomy led to an increment of serum PTH of 13% (p<0.05) compared to the SO group, while Orx+Ca decreased it by 10% (p<0.05) when compared to Orx animals. The intensity of the NaPi 2a signal was reduced in Orx rats, in comparison with the SO group. Orx+Ca 2+ treatment increased the abundance of NaPi 2a