Congenital Abnormality of Pituitary-Thyroid Axis in Spontaneously Hypertensive Rats (SHR) and Stroke-Prone Rats (SPR)

Abstract

Summary In an attempt to study whether TSH abnormality was genetically determined in SHR and SPR, plasma T₄, T₃, TSH and prolactin concentrations were measured in the animals with intervals of 1 to 3 months. Hypertension was found in 6-month-old SHR and SPR, but it was not found in younger animals. In contrast, a decrease of plasma T₃ and an increase of plasma TSH were found in 15-day-old SHR. Also, an increase of TSH was found in 1-month-old SPR in spite of normal plasma T₃ concentration. These abnormalities in SHR and SPR increased progressively with age. It is suggested that thyroid-pituitary abnormality was genetically determined in SHR and SPR.