title: Iodide and thiocyanate efflux from brain following injection into rat caudate nucleus.
abstract: Mechanisms and pathways of 125I and 35SCN efflux from the brain were investigated in anesthetized rats. Tracers were injected into the caudate nucleus through a guide cannula implanted 1 wk previously and concentrations of isotope in brain and cerebrospinal fluid (CSF) were determined at various times after injection. 125I clearance from the brain followed a single exponential curve. In control rats 36.2% of the 125I remained in the brain 30 min after injection and 60.4% in rats pretreated with perchlorate.  Comparable values for 35SCN were 25.8% in control rats, 41.0% with perchlorate, and 39.7% with iodide loading. Estimates of 125I and 35SCN effluxes from the brain via the blood-brain barrier and CSF pathways suggest that greater than 95% of efflux crosses the blood-brain  barrier. These results indicate that 1)iodide and thiocyanate are transported across the blood-brain barrier by a common mechanism, and 2) this efflux system is an important factor in the control of the distributions of iodide and thiocyanate in the central nervous system.
mesh_terms: D000818:Animals; D001345:Autoradiography; D001812:Blood-Brain Barrier; D001921:Brain / Q000378:metabolism*; D002421:Caudate Nucleus; D007454:Iodides / Q000134:cerebrospinal fluid / Q000378:metabolism*; D007457:Iodine Radioisotopes / Q000008:administration & dosage; D008297:Male; D051381:Rats; D013462:Sulfur Radioisotopes / Q000008:administration & dosage; D013861:Thiocyanates / Q000134:cerebrospinal fluid / Q000378:metabolism*; D013997:Time Factors
chemical_list: D007454:Iodides; D007457:Iodine Radioisotopes; D013462:Sulfur Radioisotopes; D013861:Thiocyanates