Alterations in the central vasopressin and oxytocin axis after lesion of a brain osmotic sensory region.
The anteroventral region of the third ventricle (AV3V) is critical in mediating osmotic sensitivity. AV3V lesions increase plasma osmolality and block osmotic-induced vasopressin (VP) and oxytocin (OT) secretion. The aim was to evaluate the effects of AV3V lesions on neurosecretion under control/water replete conditions and after 48 h dehydration. The focus was on central peptidergic changes with measurement of OT and VP content in the hypothalamic paraventricular (PVN) and supraoptic (OT) regions and the posterior pituitary. AV3V-lesioned rats exhibited an elevated plasma osmolality and higher OT content in SON and PVN. There was an increase in VP content in PVN, but no change in SON. As predicted, the plasma peptide response to dehydration was absent in lesioned animals. However, dehydration produced depletion in posterior pituitary VP in lesioned animals with no change in OT. No changes in nuclear VP and OT levels were seen after dehydration. These results demonstrate that AV3V lesions alter the VP and OT neurosecretory system, seen as a blockade of osmotic-induced release and an increase in basal nuclear peptide content. The data indicate that interruption of the osmotic sensory system affects the central neurosecretory axis, resulting in a backup in content and likely changes in synthesis and processing.
Oliveira
Gabriela R
GR
Departamento de Morfologia, Estomatologia e Fisiologia da Faculdade de Odontologia de Ribeirão Preto, Universidade de São Paulo, Av. do Café s/n, CEP 14049-900 Ribeirão Preto, Brazil.
Franci
Celso R
CR
Rodovalho
Gisele V
GV
Franci
Janete A A
JA
Morris
Mariana
M
Rocha
Maria José A
MJ
D000818:Animals; D001927:Brain Diseases / Q000378:metabolism; D003681:Dehydration / Q000378:metabolism; D007030:Hypothalamo-Hypophyseal System / Q000502:physiology*; D008297:Male; D042282:Microdissection / Q000379:methods; D009994:Osmolar Concentration; D009997:Osmotic Pressure; D010121:Oxytocin / Q000378:metabolism*; D010286:Paraventricular Hypothalamic Nucleus / Q000187:drug effects / Q000378:metabolism; D010913:Pituitary-Adrenal System / Q000502:physiology*; D011863:Radioimmunoassay; D051381:Rats; D017208:Rats, Wistar; D013495:Supraoptic Nucleus / Q000187:drug effects / Q000378:metabolism; D020542:Third Ventricle / Q000293:injuries* / Q000378:metabolism; D014667:Vasopressins / Q000378:metabolism*; D014867:Water / Q000494:pharmacology; D014882:Water-Electrolyte Balance / Q000187:drug effects / Q000502:physiology*
D014867:Water; D014667:Vasopressins; D010121:Oxytocin