Enhanced phosphoinositol hydrolysis in response to vasopressin in the septum of the homozygous brattleboro rat

L. M. Shewey, M. D. Brot, P. Szot, D. M. Dorsa

Research output: Contribution to journalArticle

17 Scopus citations

Abstract

Arginine8-vasopressin (AVP) receptors in the septum of the Long-Evans rat have been shown to be both pharmacologically (displacement profiles) and functionally (ability to stimulate phosphoinositide hydrolysis) similar to the peripheral V1-type receptor for AVP. Previous binding studies of AVP receptors in the septum of heterozygous (HE) and homozygous (vasopressin-deficient, HO) Brattleboro (BB) rats revealed an increased number of receptors with a lower affinity for AVP in the HO-BB rat when compared to the HE-BB rat. To determine the effect of these receptor changes in the HO-BB rat septum on the postreceptor response of the tissue to AVP, concentration-response relationships for AVP-stimulated phosphoinositide hydrolysis were examined in septal slices from age-matched, adult male HE- and HO-BB rats. AVP-stimulated accumulation of [3H]inositol-1-phosphate (IP1) was significantly greater in the HO-BB (43.7%) than in the HE-BB (13.7%) at AVP concentrations of 10-08 to 10-05 M. The two groups did not, however, differ in their ability to stimulate [3H]IP1 accumulation in response to 2.0 nM carbochol. When the AVP-stimulated phosphoinositide response in both genotypes was compared to that obtained for the Long-Evans (LE) rat (the parent strain of the Brattleboro rat) septum under the same assay conditions, it was found that the response in the HE-BB was much lower in the LE, AVP receptor binding capacity (Bmax correlated (r = 0.975) with release of IP1 [3H]P1 accumulation) for all 3 groups studied (LE, HE, HO). These results indicate that Brattleboro rats do posses functional receptors for AVP in the septum, and that the postreceptor response in the septum of the HO-BB rat is much larger than in the HE-BB rat.

Original languageEnglish (US)
Pages (from-to)95-102
Number of pages8
JournalBrain research
Volume478
Issue number1
DOIs
StatePublished - Jan 23 1989

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Keywords

  • Brattleboro rat
  • Phosphoinositide hydrolysis
  • Receptor
  • Septum
  • Vasopressin

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology

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