ANESTHESIA WITH ALPHAXALONE PLUS ALPHADOLONE ACETATE BLOCKS THE ESTROGEN-STIMULATED LH SURGE AND IMPAIRS PULSATILE LH-SECRETION IN OVARIECTOMIZED FEMALE RATS

Two experiments were undertaken to assess further the action of the steroid anesthetic alphaxalone upon LH [luteinizing hormone] secretion in chronically ovariectomized female rats. For the 1st experiment, 31 rats were given 2 injections of estradiol benzoate (20 .mu.g/100 g body wt), each 72 h apart, to stimulate an LH surge 6 h after the 2nd injection. However, 1 group of 7 rats was anesthetized with alphaxalone throughout the 6-h period and a 2nd group of 8 was similarly anesthetized only for the last 2 h of the 6-h period. The steroid-stimulated LH surge was blocked in both groups of rats anesthetized with alphaxalone. The 2nd experiment involved a comparison of pulsatile LH secretion in animals which were either unanesthetized (no. = 8) or anesthetized with alphaxalone (no. = 9). In 6 out of 9 rats the anesthetic did not affect the maximum or minimum plasma LH concentrations but significantly slowed the frequency at which LH pulses were measured. In the remaining 3 anesthetized rats the drug blocked pulsatile LH secretion. Some secretion of LH continues during alphaxalone anesthesia but indicates also that the drug has a more deleterious action upon the estrogen-stimulated LH surge than believed hitherto.