TRANSIENT EXPRESSION OF CALRETININ IN THE TROUT HABENULO-INTERPEDUNCULAR SYSTEM DURING DEVELOPMENT

Calcium-binding proteins control calcium homeostasis during neural dev elopment. The expression of one of these proteins, calretinin (CR), wa s monitored by immunohistochemistry in the developing habenulo-interpe duncular system of the rainbow trout, a conserved region of the brain along vertebrate phylogeny that undergoes a neurochemical reorganizati on in late development. No CR-immunoreactivity was observed in the hab enulo-interpeduncular system during the embryonic development. CR-immu nolabeling appeared in newly hatched fry and during the fry developmen t the number of CR-immunostained elements increased progressively. Dur ing the juvenile stages (from 30 days post-hatching onwards) a gradual decrease in the number of CR-immunostained cells occurred, until its complete disappearance in adults. These variations in CR expression ma y represent the variable calcium-buffering needs during different deve lopmental stages. (C) 1998 Elsevier Science Ireland Ltd. All rights re served.