Is neurotransmitter release involved in the mechanism of general anesthesia?

INTRODUCTION: It is believed that neurotransmitters release modulates general anesthesia via several receptors system which are molecular targets for anesthetic agents in young-adult rats. However, middle-aged rats have rarely been used. Therefore, we studied in this age group.

MATERIALS AND METHODS: After approval of our protocol by the institutional committee on animal research, 116 middle aged Sprague-Dawley rats were assigned to ketamine (K: n = 74) and propofol (P: n = 42) anesthesia groups. Rats were decapitated 0, 20 60 and 120 min after ip K (100 mg/kg) or P (80 mg/kg), respectively. Melanin-concentrating hormone (MCH), orexin A (OXA) and noradrenaline contents in the pons, hypothalamus, hippocampus and cerebrocortex were measured by a commercial enzyme-linked immunosorbent assay (ELISA) or high-performance liquid chromatography.

RESULTS: Neurotransmitter content in all brain regions did not significantly change following K or P administration.

CONCLUSION: Therefore, we question whether neurotransmitter release contributes to general anesthesia.