A study of the role of neuro-glial remodeling in the oxytocin system at lactation.
Neuroscience. 2006-01-01; 137(1): 309-316
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1. Neuroscience. 2006;137(1):309-16. Epub 2005 Oct 10.
A study of the role of neuro-glial remodeling in the oxytocin system at
Catheline G(1), Touquet B, Lombard MC, Poulain DA, Theodosis DT.
(1)INSERM, U378, Institut François Magendie, Université Victor Segalen Bordeaux
II, Bordeaux cedex, F-33077 France.
Under conditions of strong secretion of neurohypophysial hormone, such as during
parturition, lactation and dehydration, the hypothalamic oxytocin-system displays
a remarkable morphological plasticity such that astrocytic coverage of its
neurones diminishes, their surfaces become directly juxtaposed and contacted by
an increased number of synapses. A growing body of evidence indicates that these
anatomical changes have an impact on glutamatergic neurotransmission in the
supraoptic nucleus, and may be therefore of physiological consequence. We here
evaluated the consequences of the inhibition of such plasticity on the overall
activity of the oxytocin system during lactation. Remodeling was prevented by
performing hypothalamic microinjections in gestating rats of endoneuraminidase,
an enzyme that removes polysialic acid from the neural cell adhesion molecule.
Our earlier studies established that the presence of polysialic acid is a
prerequisite for remodeling of the oxytocin system in the supraoptic and
paraventricular nuclei. In dams in which polysialic acid was absent in all
magnocellular nuclei after bilateral endoneuraminidase injections, parturition
was normal and neither the frequency nor the amplitude of suckling-induced reflex
milk ejections was different from vehicle-treated dams. The weight gain of pups
was also normal as was water intake by the dams. We then assessed the electrical
activity of antidromically identified magnocellular neurones in the polysialic
acid-free supraoptic nucleus of isoflurane-anesthetized lactating rats. Basal and
bursting activity characteristic of oxytocin neurones before each reflex milk
ejection was not significantly different from that recorded in the supraoptic
nucleus of rats with normal levels of polysialic acid. Our results indicate that
neuro-glial remodeling, despite its role on fine modulation of oxytocin neuronal
activity, is not essential to parturition and lactation.
PMID: 16216421 [Indexed for MEDLINE]