Effects of Halothane and Methoxyflurane on Regional Brain and Spinal Cord Substance P-Like and Beta-Endorphin-Like Immunoreactivities in the Rat

• Published in: Brain research bulletin 1998-03, Vol.45 (5), p.501-506
• Main Authors: Karuri, A.R, Agarwal, R.K, Engelking, L.R, Kumar, M.S.A
• Format: Article
• Language: English
• Subjects: Analysis of Variance; Anesthetics. Neuromuscular blocking agents; Animals; beta-Endorphin - metabolism; Biological and medical sciences; Brain - drug effects; Brain - metabolism; CNS; Halothane; Halothane - pharmacology; Kinetics; Male; Medical sciences; Methoxyflurane; Methoxyflurane - pharmacology; Neuropharmacology; Opioids; Organ Specificity; Pharmacology. Drug treatments; Pituitary; Posture; Radioimmunoassay; Rats; Rats, Sprague-Dawley; Reflex - drug effects; Sensitivity and Specificity; Spinal cord; Spinal Cord - drug effects; Spinal Cord - metabolism; Substance P; Substance P - metabolism; Time Factors; β-endorphin
• ISSN: 0361-9230; 1873-2747
• DOI: 10.1016/S0361-9230(97)00436-X

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 β-endorphin (β-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 β-end-like immunoreactivity in the olfactory bulbs and thalami at 2, 4, and 24 h. However, halothane alone significantly elevated β-end-like immunoreactivity in the spinal cord at 24 h. Halothane significantly elevated PIT β-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 β-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 β-end secreting neurons in the CNS.