Regional differences in postweaning growth by choroid plexuses as affected by dietary salt deficiencies

Abstract A diet low in K and Na given to postweaning rats of the Berkeley S1 strain led in two experiments to a greater than normal relative weight of the choroid plexus of ventricle IV (= C.P. IV) to weight of the whole brain in both sexes. This effect did not occur in the choroid plexuses of ventricles I + II (= C.P. I + II) and III (= C.P. III), which were lower than normal in absolute weights and unchanged in ratios with whole brain weights after the low K and Na diet. Quantitative microscopic tissue analyses of the choroid plexuses following one of the experiments failed to demonstrate significant differences in relative tissue composition or cellular structure after this diet. Other evidence, and data on normal postnatal growth of choroid plexuses, suggests that the unequal apparent responses of the different choroid plexus regions to the diet are related to differences in their durations and rates of growth after weaning rather than to a necessarily specific cellular response in the choroid plexus of ventricle IV to internal consequences of dietary restriction in K and Na.