Radioiodide Uptake in Brain, CSF, Thyroid, and Salivary Glands of Audiogenic Seizure Mice

Abstract

DBA/2J (DBA) mice are susceptible to audiogenic seizures (ASs) in an age-dependent manner. Anion transport as measured by radioiodide uptake was determined in thyroid gland, salivary gland, skeletal muscle, cerebral cortex, cerebellum, brainstem, and CSF from these mice at various ages. Anion transport was also determined in C57BL/6J(C57) mice, an AS-resistant strain. In thyroid, DBA mice had an enhanced ability to concentrate iodide at 21 days of age when they have maximal AS susceptibility, as compared with the same-aged C57 mice. This difference in thyroid function was less marked at 40 days of age, when DBA mice are less AS susceptible, and was absent at 110 days of age, when DBA mice are AS resistant. In brain, differences in iodide uptake were also noted between these two strains of mice at 21 days of age. DBA mice had an increased concentration of iodide in CSF, an indication that they have a defect in the transport of iodide out of the CSF across the choroid plexus. In addition, DBA mice had a lower ratio of cerebral cortex to CSF iodide, which suggests that DBA mice have a defect in the transport of this anion into cerebral cortical cells from brain interstitial fluid. These differences in iodide transport in brain decreased with age as the AS susceptibility of DBA mice decreased. These results suggest a relation between anion transport in thyroid gland, cerebral cortex, and choroid plexus and AS susceptibility in DBA mice at 21 days of age.

Subcellular Distribution of Carbonic Anhydrase and Na+,K+‐ and HCO3‐‐ATPases in Brains of DBA and C57 Mice

“…Since the role of CA in salivary gland tissue is uncertain, a decrease in activity of this enzyme here is of uncertain consequence. However, this finding does give additional support for an inverse relation between CA activity and 1251 transport, since 1251 transport is increased in salivary gland tissue from DBA mice at 21 days of age (Engstrom et al, 1984).…”

“…This relation is also present in DBA mice at 21 days. Thus, 1251 uptake studies in 21-day-old DBA mice demonstrated a decrease in iodide transport in cerebral cortex (Engstrom et al, 1984), and the present investigation demonstrated an increase in CA activity in cerebral cortex homogenates from DBA mice at this age. This finding may be explained if bicarbonate and iodide compete for the same transport system.…”

“…have also been investigated because a proper electrolyte balance in the neuronal microenvironment is essential for normal neuronal function. These investigations have shown that there is an alteration in anion transport of the brain of DBA mice (Engstrom et al, 1984; see review by Seyfried, 1982), suggesting that AS susceptibility may, at least in part, result from an electrolyte imbalance in the brain.…”

Seizure Susceptibility in DBA and C57 Mice: The Effects of Various Convulsants

“…Additional studies have shown that there is a decrease in anion transport in cerebral cortical cells of DBA mice at the age of maximal susceptibility to AGSs (Engstrom et al, 1984). Also, it has been shown that there is a decrease in density and an increase in atfinity of GABA binding sites in brain from DBA mice when they are susceptible to AGSs (see review by Seyfried, 1982).…”

Acute and Chronic Acetazolamide Administration in DBA and C57 Mice: Effects of Age

“…Thus, because anion transport systems are compromised in brain from DBA mice (Engstrom et al, 1984a), an increase in CA activity may be aimed at overcoming this defect. Also, increased CA activity may be a response to handle a greater metabolic load of C 0 2 resulting from neuronal hyperactivity in these seizuresusceptible mice.…”