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Retinal vasoactive intestinal peptide amacrine cells (VIP-ACs) play an important role in various retinal light-mediated pathological processes related to different developmental ocular diseases and even mental disorders. It is important to characterize the developmental changes in VIP-ACs to further elucidate their mechanisms of circuit function. We bred VIP-Cre mice with Ai14 and Ai32 to specifically label retinal VIP-ACs. The VIP-AC soma and spine density generally increased, from postnatal day (P)0 to P35, reaching adult levels at P14 and P28, respectively. The VIP-AC soma density curve was different with the VIP-AC spine density curve. The total retinal VIP content reached a high level plateau at P14 but was decreased in adults. From P14 to P16, the resting membrane potential (RMP) became more negative, and the input resistance decreased. Cell membrane capacitance (MC) showed three peaks at P7, P12 and P16. The RMP and MC reached a stable level similar to the adult level at P18, whereas input resistance reached a stable level at P21. The percentage of sustained voltage-dependent potassium currents peaked at P16 and remained stable thereafter. The spontaneous excitatory postsynaptic current and spontaneous inhibitory postsynaptic current frequencies and amplitudes, as well as charge transfer, peaked at P12 to P16; however, there were also secondary peaks at different time points. In conclusion, we found that the second, third and fourth weeks after birth were important periods of VIP-AC development. Many developmental changes occurred around eye opening. The development of soma, dendrite and electrophysiological properties showed uneven dynamics of progression. Cell differentiation may contribute to soma development whereas the changes of different ion channels may play important role for spine development. The second, third and fourth weeks after birth were important periods of VIP-AC development. VIP::Ai14 and VIP::Ai32 mice were used for soma and spine analysis, respectively. The developmental curves for VIP-AC soma have a distinct and longer platform, whereas the developmental curves for spine have a longer and smoother slopes. When the number of VIP-AC some is increasing, cell differentiation may play an important role. During the development of spine, the development of different ion channels is the most vital events. Kv-Ka represents the ion channels that conduct Ka, Kv-Kdr represents the ion channels that conduct Kdr, GABAR represents the inhibitory transmission and NMDAR represents the excitatory transmission. The events occur chronologically from left to right. [ABSTRACT FROM AUTHOR]

Despite extensive characterization of sex differences in the medial preoptic area (mPOA) of the hypothalamus, we know surprisingly little about whether or how male and female mPOA neurons differ electrophysiologically, especially in terms of neuronal firing and behavioral pattern generation. In this study, by performing whole-cell patch clamp recordings of the mPOA, we investigated the influences of sex, cell type, and gonadal hormones on the electrophysiological properties of mPOA neurons. Notably, we uncovered significant sex differences in input resistance (male > female) and in the percentage of neurons that displayed post-inhibitory rebound (male > female). Furthermore, we found that the current mediated by the T-type Ca2+ channel (IT), which is known to underlie post-inhibitory rebound, was indeed larger in male mPOA neurons. Thus, we have identified salient electrophysiological properties of mPOA neurons, namely IT and post-inhibitory rebound, that are male-biased and likely contribute to the sexually dimorphic display of behaviors. [ABSTRACT FROM AUTHOR]

Mutations in the sodium channel gene, SCN1A (Na1.1), have been linked to a spectrum of epilepsy syndromes, and many of these mutations occur in the pore region of the channel. Electrophysiological characterization has revealed that most SCN1A mutations in the pore region result in complete loss of function. SCN3A mutations have also been identified in patients with epilepsy; however, mutations in this pore region maintain some degree of electrophysiological function. It is thus speculated that compared to SCN3A disruptions, SCN1A mutations have a more pronounced effect on electrophysiological function. In this study, we identified a novel mutation, N302S, in the SCN3A pore region of a child with epilepsy. To investigate if mutations at the pore regions of SCN3A and SCN1A have different impacts on channel function, we studied the electrophysiological properties of N302S in Na1.3 and its homologous mutation (with the same amino acid substitution) in Na1.1 (N301S). Functional analysis demonstrated that SCN1A-N301S had no measurable sodium current, indicating a complete loss of function, while SCN3A-N302S slightly reduced channel activity. This observation indicates that the same pore region mutation affects SCN1A more than SCN3A. Our study further revealed a huge difference in electrophysiological function between SCN1A and SCN3A mutations in the pore region; this might explain the more common SCN1A mutations detected in patients with epilepsy and the more severe phenotypes associated with these mutations. [ABSTRACT FROM AUTHOR]

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1. Intrasomal recordings of potentials produced by current stimulation in vivo were made from 24 (A-β) touch and 19 vibrotactile neurons in the trigeminal ganglion of 29 crotaline snakes, Trimeresurus flavoviridis. 2. Usually touch neurons responded with a single action potential at the beginning of a prolonged depolarizing pulse, whereas all vibrotactile neurons responded with multiple spikes. 3. The electrophysiological parameters examined were membrane potential, threshold current, input resistance and capacitance, time constant, rebound latency, and its threshold current. Touch neurons had higher input resistance (and lower input capacitance) than vibrotactile neurons. 4. In conclusion, current injection, which elicits a single or multiple spiking, seems a useful way to separate touch neurons from vibrotactile neurons without confirming the receptor response, and some membrane properties are also specific to the sensory modality. [ABSTRACT FROM AUTHOR]

In an ontogenetic study, combining morphological analysis and patch clamp recordings, a transiently appearing horizontal cell type was identified in the dentate gyrus. The cells were exclusively located in the outer third of the stratum moleculare. They were present at postnatal day 2 (P2) and could be identified with fluorescent dyes until around P14. The morphology was bipolar, with a putative axonal and a dendritic process stretching out parallel to the pial surface without any preferential direction. Patch clamp studies in the current and voltage clamp mode were performed in hippocampal slices on visually identified horizontal cells, between P4 and P7, which were subsequently stained with lucifer yellow. The cells had a low resting membrane potential, around - 55 mV. They were excitable, displaying broad action potentials (duration 3-20 ms) and, unlike mature dentate granule cells, they also expressed a strong delayed inward rectifier with properties reminiscent of the I current. Unlike granule cells, no postsynaptic signals could be observed during elevation of [K] or electrical stimulation, suggesting that the horizontal cells did not participate in functional hippocampal circuitry. We suggest that these cells represent migrating cells with subsequent differentiation to granule cells or inhibitory interneurons. Alternatively they may be part of the early radial glia or serve as transient target cells for afferent fibres between the entorhinal cortex and the dentate gyrus. [ABSTRACT FROM AUTHOR]