Effects of halothane on the development of rat brain: a golgi study of dendritic growth.

Dendritic growth was studied in rats exposed to halothane in utero for the entire gestation period and 60 days after birth. The exposure conditions were control, intermittent halothane (25 +/- 5 ppm or 100 +/- 5 ppm, 8 h/day, 5 days/week), or continuous halothane (25 +/- 5 ppm, 24 h/day, 7 days/week). Dendritic growth in terms of branch numbers and length was most advanced in the control groups, followed by those groups exposed to 25 +/- 5 ppm halothane intermittently, 25 +/- 5 ppm halothane continuously, and 100 +/- 5 ppm halothane intermittently. The latter two exposure conditions exerted identical effects on dendritic growth. The order of this dendritic growth level established at 5 postnatal days remained the same throughout the first 95 postnatal days in both the entorhinal cortex and subiculum. The effect of halothane on dendritic growth appeared to be enduring, and the delay in the initial dendritic growth caused by halothane was not compensated for by an increased rate of dendritic growth.