Facilitatory effect of oxytocin on oxytocin cell background activity in the rat is suckling-dependent

Meyer, C.; Freund-Mercier, Marie José; Richard, Ph.

doi:10.1016/0304-3940(87)90079-6

Cited by 12 publications

(7 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Under in vivo conditions, the basal firing rate of OT neurons in lactating rats is low, and OT fails to facilitate OT neuronal activity in the absence of suckling stimulation (18). Possibly, basal firing activity of OT neurons may have already adapted to basal OT levels in that situation, as the higher concentrations of exogenous OT produced only permissive effects for the actions of other neuroactive substances during suckling stimulation (5,6).…”

Section: Discussionmentioning

confidence: 99%

Autofeedback effects of progressively rising oxytocin concentrations on supraoptic oxytocin neuronal activity in slices from lactating rats

Wang¹,

Ponzio²,

Hatton³

2006

American Journal of Physiology-Regulatory, Integrative and Comp

View full text Add to dashboard Cite

Suckling stimuli induce somatodendritic oxytocin (OT) release from supraoptic nucleus (SON) neurons, which raises intranuclear OT concentrations and contributes to the effectiveness of the milk-ejection reflex. To clarify how such changes in OT concentrations modulate the activity of OT neurons, we examined OT effects using whole cell patch-clamp recordings from SON neurons in slices from lactating rats. Progressive increases from extremely low OT concentrations (0.1-10 fM) to high concentrations (0.1-10 nM) induced excitation and subsequent spike frequency reduction (SFR) in OT neurons. Significant effects of OT on firing rates were observed starting at 1 fM, reached peak level from 1 fM to 1 pM before SFR occurred in most neurons. The buildup of OT concentrations progressively promoted depolarization of membrane potential, spike broadening, decreases in spike amplitude, and increases in the rise time of spike afterhyperpolarizations, which were unrelated to firing rate. However, intermittent application of OT (1 fM, 1 pM, and 1 nM, each for 5 min) evoked dose-dependent excitation but not the SFR. Application of 1 pM OT for 40 min simulated the effects of progressively increasing OT concentrations. Vasopressin neurons were also activated by OT but did not show SFR. Consistent with presynaptic loci of OT action, ionotropic glutamate receptor antagonists reduced OT effects on firing rate, whereas bicuculline did not change the excitatory effects. These results suggest that the specific autoregulatory effects of OT, and perhaps other neuropeptides as well, are time and concentration dependent.

show abstract

Section: Discussionmentioning

confidence: 99%

Autofeedback effects of progressively rising oxytocin concentrations on supraoptic oxytocin neuronal activity in slices from lactating rats

Wang¹,

Ponzio²,

Hatton³

2006

American Journal of Physiology-Regulatory, Integrative and Comp

View full text Add to dashboard Cite

show abstract

“…Receptors inside (and outside) the hypothalamic nuclei would then enable AVPjOXT to have distinct, but coordinated actions in different areas typical of the overall functions of the area concerned. In that way intranuclear release of OXT probably facilitates its coordinated, pulsatile release into blood in response to suckling (49,(53)(54)(55).…”

Section: Mechanisms Of Intvacerebral Releasementioning

confidence: 99%

“…The increased intranuclear release of AVP in response to direct osmotic stimulation, on the other hand, was blocked by a combined V1/V2 antagonist, further confirming a receptormediated, positive feedback action not only in the septum (52), but also in the hypothalamus. Compared to hypothalamic OXT neurons for which a positive feedback effect may be involved in neuronal synchronization and enhanced electrical activity (29,(53)(54)(55), the physiological significance of this action of AVP is less clear. The finding, however, that the intranuclear AVP release is somehow involved in improved social recognition (see 3.2.)…”

Section: Mechanisms Of Intvacerebral Releasementioning

confidence: 99%

Intracerebrally Released Vasopressin and Oxytocin: Measurement, Mechanisms and Behavioural Consequences

Landgraf

1995

J Neuroendocrinology

103

View full text Add to dashboard Cite

“…Such changes in membrane potential could only exist during suckling: the increase in oxytocin cell firing in response to i.c.v. oxytocin injection (indicating change in membrane properties) only occurs if the young are sucking (Meyer, Freund-Mercier & Richard, 1987). During suckling, the release of oxytocin inside the magnocellular nuclei probably results from excitatory afferents continually reaching the oxytocin cells.…”

Section: Cell Recruitmentmentioning

confidence: 99%

Characteristics of early‐ and late‐recruited oxytocin bursting cells at the beginning of suckling in rats.

Moos

Richard

1988

The Journal of Physiology

View full text Add to dashboard Cite

1. Paired or single recordings of paraventricular and/or supraoptic oxytocin cells at the beginning of suckling in urethane-anaesthetized rats enabled us to study cell recruitment and compare the characteristics of the early- and late-recruited cells. This was done under different experimental conditions, i.e. when the reflex was triggered in less than 1 h suckling (control), and when its triggering was facilitated either by the intraventricular (i.c.v.) injection of oxytocin, of apomorphine (a dopamine agonist) or by the intravenous (i.v.) injection of propranolol (a beta-adrenoceptor antagonist) into suckled rats with no milk ejection. 2. Under control conditions, the amplitude (total number of spikes) of the successive bursts of the early-recruited cells progressively increased, generally reaching maximum by the 6th burst. This increase was more rapid and greater after oxytocin than under control conditions or after apomorphine injection, and was delayed and reduced after propranolol. The burst frequency was higher after oxytocin and apomorphine injections than under control conditions and very low after propranolol. 3. Late-recruited cells were observed under all experimental conditions, except after oxytocin injection, since all cells displayed bursts right away. Moreover, when injected during the recruitment period of a control reflex, oxytocin greatly speeded up the recruitment of the late-recruited cells. These cells generally displayed smaller amplitude bursts than the early-recruited cells. Moreover, the increase in burst amplitude was less marked for the late- than for the early-recruited cells and often was not sustained. 4. Neither the likelihood of recruitment of an oxytocin cell nor its burst amplitude could be correlated with background activity level and there was no clear relationship between the recruitment period or the bursting characteristics on one hand and the background activity on the other. 5. In conclusion, the differences between the early- and late-recruited cells in recruitment time and in burst amplitude reflected differences in cell excitability which may depend mainly on the presence of oxytocin in the magnocellular nuclei.

show abstract

Facilitatory effect of oxytocin on oxytocin cell background activity in the rat is suckling-dependent

Cited by 12 publications

References 11 publications

Autofeedback effects of progressively rising oxytocin concentrations on supraoptic oxytocin neuronal activity in slices from lactating rats

Autofeedback effects of progressively rising oxytocin concentrations on supraoptic oxytocin neuronal activity in slices from lactating rats

Intracerebrally Released Vasopressin and Oxytocin: Measurement, Mechanisms and Behavioural Consequences

Characteristics of early‐ and late‐recruited oxytocin bursting cells at the beginning of suckling in rats.

Contact Info

Product

Resources

About