Saline preference of cross-suckled spontaneously hypertensive and normotensive rats

Two-bottle, saline preference tests were conducted on spontaneously hypertensive rats (SHR) of the Okamoto strain, normotensive Sprague-Dawley (SD) rats, SHR suckled from immediately after birth on SD foster mothers and SD suckled on SHR dams. Cross-suckling failed to alter the exaggerated saline preference of the SHR measured at 3 or 6 months of age. However, SD suckled on SHR exhibited a significantly reduced saline preference when compared to SD suckled on their natural mother. Plasma renin activity and angiotensin enzyme activity were not different between groups and saline preference did not correlate with either enzyme level. While this raises the possibility that the exaggerated saline preference of the SHR may be largely genetically determined, the role of some humoral factor in utero in the development of this appetite cannot be ruled out. The nature of the factor transferred from SHR mothers, which reduced saline preference in cross-suckled SD, remains to be determined. The possibility that this altered preference is due to a peculiarity of SHR maternal behaviour cannot be ruled out.