ISSN:
1573-6830
Keywords:
oxytocin
;
synaptic plasticity
;
neuronal–glial interactions
;
astrocytes
;
cell adhesion molecules
;
extracellular matrix
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract 1. The adult hypothalamoneurohypophysial system (HNS) undergoes reversible morphological changes in response to physiological stimulation. 2. In the hypothalamus, stimulation of neurohormone secretion results in reducedastrocytic coverage of oxytocinergic somata and dendrites so that their surfaces becomedirectly juxtaposed. Concurrently, there is a significant increase in the number of GABAergic, glutamatergic, and noradrenergic synapses impinging on the neurons. 3. In the neurohypophysis, stimulation induces retraction of pituicyte processes fromthe perivascular area and enlargement and multiplication of neurosecretory terminals. 4. These neuronal-glial and synaptic changes are reversible with cessation of stimulation, thus rendering the HNS an excellent model to study physiologically linked structuralneuronal plasticity in the adult CNS. 5. We still do not know the cellular mechanisms and factors underlying such plasticity.Recent studies indicate, however, that the adult HNS expresses molecular characteristicsnormally associated with histogenesis and/or tissue reorganization in developing or regenerating neural systems. They include expression of cell adhesion molecules such as the highlysialylated isoform of the neural cell adhesion molecule, PSA-NCAM, and the glycoproteins, F3 and tenascin-C. 6. The expression of PSA-NCAM and tenascin-C does not show striking differencesin terms of age, sex or physiological condition but that of F3 varies considerably withneurohypophysial stimulation. 7. We postulate that such molecular features allow magnocellular neurons and theirglia to undergo neuronal-glial and synaptic plasticity throughout life, provided the properstimulus intervenes. 8. Thus, in the hypothalamic nuclei, centrally released oxytocin acting in synergy with steroids can induce such plasticity, while adrenaline, acting through β-adrenergic mechanisms, does so in the neurohypophysis.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1022577105819
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