Leukotriene C4 binding sites in the rat central nervous system

Binding sites for [3H]LTC4 were observed in crude membrane preparations of rat central nervous system tissue. Equilibrium binding studies indicated one high affinity [3H]LTC4 binding site with a KD of 31.4 +/- 3.4 nM for whole brain preparations. The binding was highly specific for [3H]LTC4 and could be inhibited by the SRS-A antagonist FPL 55172. Specific binding was increased with both mono- and di-valent ions. Regional distribution studies revealed a three-fold difference in binding capacity within different regions of the brain with the highest binding capacity in the brainstem (94.1 +/- 6.9 fmol/mg of protein) and the lowest in the hypothalamus (29.6 +/- 12.8 fmol/mg of protein). In addition, weak low capacity binding was observed for [3H]LTB4 and [3H]LTE4, while no saturable binding was observed for [3H]LTD4. The order of selectivity in inhibiting [3H]LTC4 binding was LTC4 much greater than LTD4 = LTE4 greater than LTB4.