PMID- 26715365
OWN - NLM
STAT- MEDLINE
DCOM- 20180208
LR  - 20220716
IS  - 1365-2826 (Electronic)
IS  - 0953-8194 (Print)
IS  - 0953-8194 (Linking)
VI  - 28
IP  - 4
DP  - 2016 Apr
TI  - Oxytocin Neurones: Intrinsic Mechanisms Governing the Regularity of Spiking 
      Activity.
PG  - n/a
LID - 10.1111/jne.12358 [doi]
AB  - Oxytocin neurones of the rat supraoptic nucleus are osmoresponsive and, with all 
      other things being equal, they fire at a mean rate that is proportional to the 
      plasma sodium concentration. However, individual spike times are governed by 
      highly stochastic events, namely the random occurrences of excitatory synaptic 
      inputs, the probability of which is increased by increasing extracellular osmotic 
      pressure. Accordingly, interspike intervals (ISIs) are very irregular. In the 
      present study, we show, by statistical analyses of firing patterns in oxytocin 
      neurones, that the mean firing rate as measured in bins of a few seconds is more 
      regular than expected from the variability of ISIs. This is consistent with an 
      intrinsic activity-dependent negative-feedback mechanism. To test this, we 
      compared observed neuronal firing patterns with firing patterns generated by a 
      leaky integrate-and-fire model neurone, modified to exhibit activity-dependent 
      mechanisms known to be present in oxytocin neurones. The presence of a prolonged 
      afterhyperpolarisation (AHP) was critical for the ability to mimic the observed 
      regularisation of mean firing rate, although we also had to add a depolarising 
      afterpotential (DAP; sometimes called an afterdepolarisation) to the model to 
      match the observed ISI distributions. We tested this model by comparing its 
      behaviour with the behaviour of oxytocin neurones exposed to apamin, a blocker of 
      the medium AHP. Good fits indicate that the medium AHP actively contributes to 
      the firing patterns of oxytocin neurones during non-bursting activity, and that 
      oxytocin neurones generally express a DAP, even though this is usually masked by 
      superposition of a larger AHP.
CI  - (c) 2015 British Society for Neuroendocrinology.
FAU - Maicas Royo, J
AU  - Maicas Royo J
AD  - Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK.
FAU - Brown, C H
AU  - Brown CH
AD  - Centre for Neuroendocrinology and Department of Physiology, University of Otago, 
      Otago, New Zealand.
FAU - Leng, G
AU  - Leng G
AD  - Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK.
FAU - MacGregor, D J
AU  - MacGregor DJ
AD  - Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK.
LA  - eng
GR  - WT_/Wellcome Trust/United Kingdom
GR  - 070118/WT_/Wellcome Trust/United Kingdom
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - United States
TA  - J Neuroendocrinol
JT  - Journal of neuroendocrinology
JID - 8913461
RN  - 24345-16-2 (Apamin)
RN  - 50-56-6 (Oxytocin)
SB  - IM
MH  - Action Potentials/drug effects/*physiology
MH  - Animals
MH  - Apamin/pharmacology
MH  - Models, Neurological
MH  - Neurons/drug effects/*physiology
MH  - Osmotic Pressure/physiology
MH  - Oxytocin/*physiology
MH  - Rats
MH  - Supraoptic Nucleus/cytology/drug effects/physiology
PMC - PMC4879516
OTO - NOTNLM
OT  - computational modelling
OT  - electrophysiology
OT  - oxytocin
OT  - supraoptic nucleus
EDAT- 2015/12/31 06:00
MHDA- 2018/02/09 06:00
PMCR- 2016/05/25
CRDT- 2015/12/31 06:00
PHST- 2015/10/30 00:00 [received]
PHST- 2015/12/11 00:00 [revised]
PHST- 2015/12/26 00:00 [accepted]
PHST- 2015/12/31 06:00 [entrez]
PHST- 2015/12/31 06:00 [pubmed]
PHST- 2018/02/09 06:00 [medline]
PHST- 2016/05/25 00:00 [pmc-release]
AID - JNE12358 [pii]
AID - 10.1111/jne.12358 [doi]
PST - ppublish
SO  - J Neuroendocrinol. 2016 Apr;28(4):n/a. doi: 10.1111/jne.12358.