[Learning and memory processes during postnatal ontogenesis in rats with spontaneous hypertension]

The examination of learning and memory processes by a conditional reflectory locomotor avoidance reaction on 8-, 10-, 12-, 14-, 16-, 20-, 26-, and 50-week-old rats with spontaneous hypertension (SHR Okamoto/Aoki) revealed, up to an age of 20 weeks, correlations between the height of blood pressure and learning and memory performance by analogy with parameters of the hydrocarbon metabolism [1,2]. Three stages were observed: Stage I: Juvenile animals (8--10 weeks) with mean systolic blood pressure values of 150 to 170 torr showed a comparatively low restriction of learning and memory processes. Stage II: In adult animals (12--20 weeks) with mean systolic blood pressure values of 180 to 210 torr learning was inhibited by about 50%, while retention of memory was completely disturbed. Stage III: In old animals (26--50 weeks) with mean systolic blood pressure values above 200 torr the faculty to learn a conditional avoidance reflex was virtually lost. Destruction or blockage of hypothalamic behavioral substances are assumed to cause the derangement of learning and memory processes in spontaneously hypertensive rats.