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Electrophysiology of Hypothalamic Magnocellular Neurons In vitro: A Rhythmic Drive in Organotypic Cultures and Acute Slices.

Israel JM, Oliet SH, Ciofi P - Front Neurosci (2016)

Bottom Line: Here, we have tested whether a similar hypothesis can be derived from in vitro experiments in acute slices of the adult hypothalamus.To this aim we have screened our electrophysiological recordings of the magnocellular neurons, previously obtained from acute slices, with an analysis of autocorrelation of action potentials to detect a rhythmic drive as we recently did for organotypic cultures.This confirmed that the bursting behavior of magnocellular neurons is governed by central pattern generator networks whose rhythmic drive, and thus probably integrity, is however less satisfactorily preserved in the acute slices from adult brains.

View Article: PubMed Central - PubMed

Affiliation: U1215, Neurocentre Magendie, Institut National de la Santé et de la Recherche MédicaleBordeaux, France; Université de BordeauxBordeaux, France.

ABSTRACT
Hypothalamic neurohormones are released in a pulsatile manner. The mechanisms of this pulsatility remain poorly understood and several hypotheses are available, depending upon the neuroendocrine system considered. Among these systems, hypothalamo-neurohypophyseal magnocellular neurons have been early-considered models, as they typically display an electrical activity consisting of bursts of action potentials that is optimal for the release of boluses of the neurohormones oxytocin and vasopressin. The cellular mechanisms underlying this bursting behavior have been studied in vitro, using either acute slices of the adult hypothalamus, or organotypic cultures of neonatal hypothalamic tissue. We have recently proposed, from experiments in organotypic cultures, that specific central pattern generator networks, upstream of magnocellular neurons, determine their bursting activity. Here, we have tested whether a similar hypothesis can be derived from in vitro experiments in acute slices of the adult hypothalamus. To this aim we have screened our electrophysiological recordings of the magnocellular neurons, previously obtained from acute slices, with an analysis of autocorrelation of action potentials to detect a rhythmic drive as we recently did for organotypic cultures. This confirmed that the bursting behavior of magnocellular neurons is governed by central pattern generator networks whose rhythmic drive, and thus probably integrity, is however less satisfactorily preserved in the acute slices from adult brains.

No MeSH data available.


Electrical activity in OT neurons in organotypic cultures. Examples of two spontaneously firing cells that did not change their pattern of activity under bath application of (A) the OT peptide (10−5 M) or (B) the GABAA receptor antagonist bicuculline (Bic; 10−5 M). No rhythmic drive was detected by the AAA (insets) either before or during the application of the burst-inducing agents.
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Figure 2: Electrical activity in OT neurons in organotypic cultures. Examples of two spontaneously firing cells that did not change their pattern of activity under bath application of (A) the OT peptide (10−5 M) or (B) the GABAA receptor antagonist bicuculline (Bic; 10−5 M). No rhythmic drive was detected by the AAA (insets) either before or during the application of the burst-inducing agents.

Mentions: Briefly, as reported recently (Israel et al., 2014), in about 90% of the organotypic cultures, all the OT neurons burst in a highly coordinated manner and their individual activity according to AAA appears to be driven by a CPG network (96/107 cultures from P5 animals examined harbored bursting OT neurons). However, in the remaining 10% of the cultures, the OT neurons do not display HFBs of APs, nor qualify for a rhythmic drive when their activity is subjected to the AAA. When these neurons are challenged with the OT peptide (n = 6; Figure 2A) or the GABAA receptor antagonist bicuculline (n = 6; Figure 2B) to induce robust bursting (Jourdain et al., 1998; Israel et al., 2014), their activity remains unchanged and the AAA reveals no rhythmic drive either before or during the challenges (Figure 2).


Electrophysiology of Hypothalamic Magnocellular Neurons In vitro: A Rhythmic Drive in Organotypic Cultures and Acute Slices.

Israel JM, Oliet SH, Ciofi P - Front Neurosci (2016)

Electrical activity in OT neurons in organotypic cultures. Examples of two spontaneously firing cells that did not change their pattern of activity under bath application of (A) the OT peptide (10−5 M) or (B) the GABAA receptor antagonist bicuculline (Bic; 10−5 M). No rhythmic drive was detected by the AAA (insets) either before or during the application of the burst-inducing agents.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4814512&req=5

Figure 2: Electrical activity in OT neurons in organotypic cultures. Examples of two spontaneously firing cells that did not change their pattern of activity under bath application of (A) the OT peptide (10−5 M) or (B) the GABAA receptor antagonist bicuculline (Bic; 10−5 M). No rhythmic drive was detected by the AAA (insets) either before or during the application of the burst-inducing agents.
Mentions: Briefly, as reported recently (Israel et al., 2014), in about 90% of the organotypic cultures, all the OT neurons burst in a highly coordinated manner and their individual activity according to AAA appears to be driven by a CPG network (96/107 cultures from P5 animals examined harbored bursting OT neurons). However, in the remaining 10% of the cultures, the OT neurons do not display HFBs of APs, nor qualify for a rhythmic drive when their activity is subjected to the AAA. When these neurons are challenged with the OT peptide (n = 6; Figure 2A) or the GABAA receptor antagonist bicuculline (n = 6; Figure 2B) to induce robust bursting (Jourdain et al., 1998; Israel et al., 2014), their activity remains unchanged and the AAA reveals no rhythmic drive either before or during the challenges (Figure 2).

Bottom Line: Here, we have tested whether a similar hypothesis can be derived from in vitro experiments in acute slices of the adult hypothalamus.To this aim we have screened our electrophysiological recordings of the magnocellular neurons, previously obtained from acute slices, with an analysis of autocorrelation of action potentials to detect a rhythmic drive as we recently did for organotypic cultures.This confirmed that the bursting behavior of magnocellular neurons is governed by central pattern generator networks whose rhythmic drive, and thus probably integrity, is however less satisfactorily preserved in the acute slices from adult brains.

View Article: PubMed Central - PubMed

Affiliation: U1215, Neurocentre Magendie, Institut National de la Santé et de la Recherche MédicaleBordeaux, France; Université de BordeauxBordeaux, France.

ABSTRACT
Hypothalamic neurohormones are released in a pulsatile manner. The mechanisms of this pulsatility remain poorly understood and several hypotheses are available, depending upon the neuroendocrine system considered. Among these systems, hypothalamo-neurohypophyseal magnocellular neurons have been early-considered models, as they typically display an electrical activity consisting of bursts of action potentials that is optimal for the release of boluses of the neurohormones oxytocin and vasopressin. The cellular mechanisms underlying this bursting behavior have been studied in vitro, using either acute slices of the adult hypothalamus, or organotypic cultures of neonatal hypothalamic tissue. We have recently proposed, from experiments in organotypic cultures, that specific central pattern generator networks, upstream of magnocellular neurons, determine their bursting activity. Here, we have tested whether a similar hypothesis can be derived from in vitro experiments in acute slices of the adult hypothalamus. To this aim we have screened our electrophysiological recordings of the magnocellular neurons, previously obtained from acute slices, with an analysis of autocorrelation of action potentials to detect a rhythmic drive as we recently did for organotypic cultures. This confirmed that the bursting behavior of magnocellular neurons is governed by central pattern generator networks whose rhythmic drive, and thus probably integrity, is however less satisfactorily preserved in the acute slices from adult brains.

No MeSH data available.