Effects of halothane and methoxyflurane on regional brain and spinal cord substance P-like and beta-endorphin-like immunoreactivities in the rat.
Effects of acute exposure (2 hr) to either 1.5% halothane or 0.5% methoxyflurane were investigated in the Sprague Dawley rat. Pituitary (PIT) and central nervous system (CNS) substance P (SP)-like and beta-endorphin (beta-end)-like immunoreactivities were evaluated immediately after anesthetic exposure (2 h), after righting reflex (4 h) or 24 hr postexposure (24 h). Only halothane significantly reduced SP-like immunoreactivity in olfactory bulbs in both the 2-h and 4-h groups. Halothane elevated SP-like immunoreactivity of hippocampus at all three time periods, and in the hypothalamus at 2 h. Both anesthetics significantly depleted thalamic concentrations of SP-like immunoreactivity. Methoxyflurane anesthesia resulted in a drastic decrease in SP-like immunoreactivity in PIT at all three time periods periods, while halothane elevated PIT concentrations of this peptide at 4 h. Both anesthetics significantly decreased beta-end-like immunoreactivity in the olfactory bulbs and thalami at 2, 4, and 24 h. However, halothane alone significantly elevated beta-end-like immunoreactivity in the spinal cord at 24 h. Halothane significantly elevated PIT beta-end-like immunoreactivity at 2 and 24 h, while methoxyflurane significantly lowered it in the 4-h group, but elevated the levels of the same in the 24-h group. Brain stem beta-end immunoreactivity were significantly reduced at 2 h by both anesthetics, and at 4 h by methoxyflurane. Results indicate that halothane and methoxyflurane may differ significantly in their actions on SP and beta-end secreting neurons in the CNS.
Karuri
A R
AR
Department of Biomedical Sciences, Tufts University School of Veterinary Medicine, North Grafton, MA 01536, USA.
Agarwal
R K
RK
Engelking
L R
LR
Kumar
M S
MS
D000704:Analysis of Variance; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D006221:Halothane / Q000494:pharmacology*; D007700:Kinetics; D008297:Male; D008733:Methoxyflurane / Q000494:pharmacology*; D009928:Organ Specificity; D011187:Posture; D011863:Radioimmunoassay; D051381:Rats; D017207:Rats, Sprague-Dawley; D012018:Reflex / Q000187:drug effects; D012680:Sensitivity and Specificity; D013116:Spinal Cord / Q000187:drug effects / Q000378:metabolism*; D013373:Substance P / Q000378:metabolism*; D013997:Time Factors; D001615:beta-Endorphin / Q000378:metabolism*
D008733:Methoxyflurane; D013373:Substance P; D001615:beta-Endorphin; D006221:Halothane