Ultrastructural studies of the supraoptic nucleus ( @entity4525 ) of the hypothalamus suggest that an active retraction and extension of astrocytic processes (structural plasticity) from between magnocellular neuroendocrine neurons plays a role in the release of @entity398 , @entity1951 , or both peptides that accompanies parturition, lactation, and @entity2700 . In support of this, Salm et al. (1985) previously demonstrated a lactation-associated reduction in immunoreactive glial fibrillary acidic protein (GFAP), an astrocyte-specific cytoskeletal constituent. To determine if similar changes occur in response to @entity2700 , and if they are reversible, the present study examined GFAP-immunoreactivity (IR) in the @entity4525 under various hydration states. @entity35 were dehydrated for 7 days by substitution of drinking water with 2% saline (n = 3), or dehydrated for 7 days followed by 7 days of rehydration (n = 3). A control group (n = 3) with free access to tap water was used for comparisons. The optical density of GFAP-IR was obtained from the @entity4525 , globus pallidus, and lateral hypothalamic regions. The areas of the ventral glial limitans subjacent to the @entity4525 ( @entity4525 ) and of linearly equivalent segments of glial limitans more distant from the @entity4525 were also determined. @entity2700 resulted in a significant reduction in GFAP-IR in the @entity4525 compared to control and rehydrated levels. We also found that the area of the @entity4525 was significantly larger than that of linearly equivalent segments of glial limitans elsewhere and that it was significantly reduced in dehydrated @entity35 , returning to control levels with rehydration. GFAP-IR and glial limitans thickness in regions unrelated to body fluid homeostasis lateral to the @entity4525 , overlying to dorsal cortex, and subjacent to the optic chiasm were not significantly changed by hydration state. These results are similar to the changes of GFAP-IR reported for lactating @entity35 and provide further evidence for a role of structural plasticity of astrocytes in events surrounding the selective functional activation of local neurons.

@entity2700 and rehydration selectively and reversibly alter glial fibrillary acidic protein immunoreactivity in the XXXX supraoptic nucleus and subjacent glial limitans.

@entity398 :: ('MESH:D010121', 'Chemical') :: ['oxytocin'] @entity2700 :: ('MESH:D003681', 'Disease') :: ['Dehydration', 'dehydration'] @entity1951 :: ('MESH:D014667', 'Chemical') :: ['vasopressin'] @entity35 :: ('10116', 'Species') :: ['Rats', 'rats'] @entity4525 :: ('304092(Tax:10116)', 'Gene') :: ['SON-VGL', 'SON']
@entity35 :: (10116,Species) :: ['rat']
