The influence of anesthetics on neurotransmitters in the nervous system of Sepia pharaonis

Abstract

Anesthesia is a stress mitigation technique widely used during transportation and short-term human manipulation, such as labeling and measurement of body parameters of aquatic animals. This is because anesthetics affect the content of neurotransmitters, exerting various effects on the body. This study determined optimal anesthetic concentration for cuttlefish by measuring the anesthetic and recovery duration of Sepia pharaonis. This was assessed with Nuclear magnetic resonance (NMR) combined with high performance liquid chromatography (HPLC) detection of nervous system metabolites and specific changes in the content of six neurotransmitters. Successful anesthetization of cuttlefish was observed with ethanol concentration (10–30 mL L−1). The cuttlefish recovered after anesthesia, with the longest exposure time being 60 min at a concentration of 10 mL L−1 ethanol. Likewise, the cuttlefish also reached a sedative state at a concentration below 5 mL L−1 ethanol, but with a maximum exposure time of 270 min. We concluded that the action of ethanol attributed to the 10–20% increase of glycine and tyrosine using NMR and HPLC analysis. We postulate the anesthetic role of ethanol in cuttlefish led to increased inhibitory neurotransmitters gamma-Aminobutyric acid, (GABA) and Glycine (Gly) while it reduced the levels of excitatory neurotransmitters acetylcholine (Ach), dopamine (DA) and 5-hydroxytryptamine (5-HT).However, cuttlefish recovery from anesthesia was probably due to rising Ach and Glutamate (Glu) levels.