TY - JOUR
T1 - Changes in the electrical properties of supraoptic nucleus oxytocin and vasopressin neurons during lactation
AU - Stern, Javier E.
AU - Armstrong, William E.
PY - 1996/8/15
Y1 - 1996/8/15
N2 - Magnocellular oxytocin (OT) and vasopressin (VP) neurons adopt different firing patterns in response to relevant physiological stimuli. OT neurons selectively display short (2-4 sec), high-frequency bursts of action potentials that are highly synchronized and correlated with OT release during lactation. The present experiments were done to determine whether the electrophysiological properties of OT neurons differ from those of VP neurons, and whether these properties are modulated during lactation to support short bursting activity. Intracellular recordings in vitro were obtained from immunochemically identified supraoptic neurons of diestrous or lactating female rats. Resting membrane potential, input resistance, membrane time constant, and the depolarizing afterpotential did not differ among groups. However, near spike threshold, OT, but not VP, neurons expressed a sustained outward rectification that was removed by small hyperpolarizing pulses and a rebound depolarization that occurred at the offset of these hyperpolarizing pulses. The rebound depolarization was short (<2 sec), supported brief bursts of action potentials, and was significantly larger during lactation. Neurons expressing the outward rectification also exhibited strong spike frequency adaptation during prolonged (1-4 sec) depolarization. Spike width, the Ca2+-dependent afterhyperpolarization, and the degree of spike broadening of OT, but not VP, neurons were also larger during lactation, suggesting an increase in Ca2+ influx per spike. The results indicate that OT neurons possess properties favoring the expression of short spike trains, and that some of these properties are enhanced during lactation. In addition, spikes in OT neurons may promote more Ca2+ influx in this state.
AB - Magnocellular oxytocin (OT) and vasopressin (VP) neurons adopt different firing patterns in response to relevant physiological stimuli. OT neurons selectively display short (2-4 sec), high-frequency bursts of action potentials that are highly synchronized and correlated with OT release during lactation. The present experiments were done to determine whether the electrophysiological properties of OT neurons differ from those of VP neurons, and whether these properties are modulated during lactation to support short bursting activity. Intracellular recordings in vitro were obtained from immunochemically identified supraoptic neurons of diestrous or lactating female rats. Resting membrane potential, input resistance, membrane time constant, and the depolarizing afterpotential did not differ among groups. However, near spike threshold, OT, but not VP, neurons expressed a sustained outward rectification that was removed by small hyperpolarizing pulses and a rebound depolarization that occurred at the offset of these hyperpolarizing pulses. The rebound depolarization was short (<2 sec), supported brief bursts of action potentials, and was significantly larger during lactation. Neurons expressing the outward rectification also exhibited strong spike frequency adaptation during prolonged (1-4 sec) depolarization. Spike width, the Ca2+-dependent afterhyperpolarization, and the degree of spike broadening of OT, but not VP, neurons were also larger during lactation, suggesting an increase in Ca2+ influx per spike. The results indicate that OT neurons possess properties favoring the expression of short spike trains, and that some of these properties are enhanced during lactation. In addition, spikes in OT neurons may promote more Ca2+ influx in this state.
KW - electrophysiology
KW - lactation
KW - magnocellular cells
KW - oxytocin
KW - supraoptic nucleus
KW - vasopressin
UR - http://www.scopus.com/inward/record.url?scp=0029743051&partnerID=8YFLogxK
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U2 - 10.1523/jneurosci.16-16-04861.1996
DO - 10.1523/jneurosci.16-16-04861.1996
M3 - Article
C2 - 8756418
AN - SCOPUS:0029743051
SN - 0270-6474
VL - 16
SP - 4861
EP - 4871
JO - Journal of Neuroscience
JF - Journal of Neuroscience
IS - 16
ER -