Changes in nucleolar dry mass of neurones of the paraventricular and supraoptic nuclei in the rat during pregnancy and lactation

Russell, John A.

doi:10.1007/bf00234879

Cited by 14 publications

(5 citation statements)

References 33 publications

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“…Since our previous studies (Stern & Armstrong, 1996; Teruyama & Armstrong, 2002 a ) had suggested a common feature of AHP and DAP plasticity might be their Ca 2+ dependence, we tested whether AHP plasticity was related to changes in the whole‐cell Ca 2+ current or in [Ca 2+ ] i . Although whole‐cell Ca 2+ current did increase coincident with the somatic hypertrophy of OT neurons during lactation observed previously (Russell, 1980; Theodosis & Poulain, 1993; Brussaard et al 1999), current density was not increased. Neither did the peak Ca 2+ transient (Δ F / F ).…”

Section: Discussionsupporting

confidence: 55%

Enhancement of calcium‐dependent afterpotentials in oxytocin neurons of the rat supraoptic nucleus during lactation

Teruyama

Armstrong

2005

The Journal of Physiology

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The firing pattern of oxytocin (OT) hormone synthesizing neurons changes dramatically immediately before each milk ejection, when a brief burst of action potentials is discharged. OT neurons possess intrinsic currents that would modulate this burst. Our previous studies showed the amplitude of the Ca 2+ -dependent afterhyperpolarization (AHP) following spike trains is significantly larger during lactation. In the present study we sought to determine which component of the AHP is enhanced, and whether the enhancement could be related to changes in whole-cell Ca 2+ current or the Ca 2+ transient in identified OT or vasopressin (VP) neurons during lactation. We confirmed, with whole-cell current-clamp recordings, our previous finding from sharp electrodes that the size of the AHP following spike trains increased in OT, but not VP neurons during lactation. We then determined that an apamin-sensitive medium-duration AHP (mAHP) and an apamin-insensitive slow AHP (sAHP) were specifically increased in OT neurons. Simultaneous Ca 2+ imaging revealed that the peak change in somatic [Ca 2+ ] i was not altered in either cell type, but the slow decay of the Ca 2+ transient was faster in both cell types during lactation. In voltage clamp, the whole-cell, Ca 2+ current was slightly larger during lactation in OT cells only, but current density was unchanged when corrected for somatic hypertrophy. The currents, I mAHP and I sAHP , also were increased in OT neurons only, but only the apamin-sensitive I mAHP showed an increase in current density after adjusting for somatic hypertrophy. These findings suggest a specific modulation (e.g. increased number) of the small-conductance Ca 2+ -dependent K + (SK) channels, or their interaction with Ca 2+ , underlies the increased mAHP/I mAHP during lactation. This larger mAHP may be necessary to limit the explosive bursts during milk ejection.

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Section: Discussionsupporting

confidence: 55%

Enhancement of calcium‐dependent afterpotentials in oxytocin neurons of the rat supraoptic nucleus during lactation

Teruyama

Armstrong

2005

The Journal of Physiology

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“…It has been suggested that the cellular hypertrophy probably reflects increased synthesis of neurohormones [Sokol and Vaitin. 1965], An increment of nuclear area has also been reported in the hypothalamic neurosecretory neurons during preg nancy and lactation, which produce an increased demand of oxytocin [Russell, 1980] and in rats drinking hypertonicsolutions to create a chronic increase in plasma osmolality, which results in an increase in vasopressin production [Enestrom, 1967: Paterson andLeblond. 1977].…”

Section: Morphometric Analysismentioning

confidence: 99%

Ultrastructural Changes in the Hypothalamic Paraventricular Nucleus of the Streptozotocin-Induced Diabetic Rat

Dheen

Tay²,

Wong³

1994

Cells Tissues Organs

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This study describes the ultrastructural and morphometric changes in the hypothalamic paraventricular nucleus (PVN) of the streptozotocin-induced diabetic rat. During the acute phase (3 days after induction of diabetes), dendrites were swollen and appeared to have a watery cytoplasm. The affected dendrites were postsynaptic to seemingly normal axon terminals. During the intermediate phase (1-9 months after induction of diabetes), the neuronal somata contained numerous vacuoles of various sizes which were probably formed from dilated rough endoplasmic reticulum. Several unidentifiable vacuolated profiles were also seen in the neuropil. During the late phase (12 months after induction of diabetes) electron-dense dendrites and axon terminals were readily encountered in the neuropil. Most of the electron-dense dendrites were postsynaptic to normal as well as electron-dense axon terminals. Some of the electron-dense axon terminals formed axosomatic synapses with seemingly normal somata. Perivascular glial cells in the neuropil were in the process of phagocytosis. At 1-12 months of diabetes, the sizes of the somata and nuclei of PVN neurons were significantly increased in comparison with age-matched control rats.

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“…Taken together, these data show that the 5‐HT inhibitory influence on VIP gene expression and probably on peptide synthesis during prenatal ontogenesis is reversible. Lack of stimulating influence of 5‐HT deficiency on VIP and VP synthesis is indirectly confirmed by the absence of neuron hypertrophy (see Results) (Russel, 1980; Van Tol et al, 1987; McCabe et al, 1990).…”

Section: Discussionmentioning

confidence: 77%

Long‐lasting effects of serotonin deficiency on differentiating peptidergic neurons in the rat suprachiasmatic nucleus

Mirochnik

Bosler

Tillet³

et al. 2004

Intl J of Devlp Neuroscience

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Serotonin (5-HT, 5-hydroxytryptamine) is known to be an inductor of the brain development [Whitaker-Azmitia, P.M., Druse, M., Walker, P., Lauder, J.M., 1996. Serotonin as a developmental signal. Behav. Brain Res. 73, 19-29; Ugrumov, M.V., 1997. Hypothalamic monoaminergic systems in ontogenesis: development and functional significance. Int. J. Dev. Biol. 41, 809-816]. This study was aimed to test whether it provides long-lasting effects on the differentiating vasoactive intestinal polypeptide (VIP) and vasopressin (VP) neurons of the suprachiasmatic nucleus (SCN) in rats. To this aim, 5-HT was depleted in fetal brain by daily injections of p-chlorophenylalanine (pCPA), an inhibitor of 5-HT synthesis, to pregnant rats from the 13th to the 21st day of gestation. Pregnant rats injected with saline served as controls. The offsprings (males) of pCPA-treated and control pregnant rats were maintained after birth for two months under normal laboratory conditions. Then, the SCN was processed for immunocytochemistry of VIP and VP and in situ hybridization of appropriate mRNAs. There were no differences in concentrations of VIP and VP mRNAs in the SCN in adult offsprings of the 5-HT-depleted pregnant rats compared to the controls. Moreover, 5-HT deficiency did not induce any change in size of VIP-immunoreactive (IR) and VP-IR neurons. Conversely, both the numbers of VIP- and VP-immunoreactive neurons and concentrations of the peptides in cell bodies increased significantly. It is concluded that 5-HT provides long-lasting effects on differentiating VIP and VP neurons in the SCN resulting in attenuated release rather than elevated synthesis of both peptides in adulthood.

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Changes in nucleolar dry mass of neurones of the paraventricular and supraoptic nuclei in the rat during pregnancy and lactation

Cited by 14 publications

References 33 publications

Enhancement of calcium‐dependent afterpotentials in oxytocin neurons of the rat supraoptic nucleus during lactation

Enhancement of calcium‐dependent afterpotentials in oxytocin neurons of the rat supraoptic nucleus during lactation

Ultrastructural Changes in the Hypothalamic Paraventricular Nucleus of the Streptozotocin-Induced Diabetic Rat

Long‐lasting effects of serotonin deficiency on differentiating peptidergic neurons in the rat suprachiasmatic nucleus

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