TY - JOUR
T1 - Effects of propofol and pentobarbital on calcium concentration in presynaptic boutons on a rat hippocampal neuron
AU - Ito, Shinichi
AU - Sugiyama, Hitomi
AU - Kitahara, Seiko
AU - Ikemoto, Yoshimi
AU - Yokoyama, Takeshi
N1 - Funding Information:
This work was supported by the Japan Society for the Promotion of Science (JSPS) Grant-in-Aid for Scientific Research (21592578).
PY - 2011/10
Y1 - 2011/10
N2 - Purpose: Numerous reports suggest that intravenously administered (IV) anesthetics affect postsynaptic events in the central nervous system. However, there is little evidence about how general anesthetics influence the presynaptic processes. The level of presynaptic calcium (Ca2+) concentration ([Ca2+]pre) regulates neurotransmitter release. In this study, we investigated the effects of anesthetic propofol IV and the barbiturate pentobarbital on neurotransmitter release by measuring [Ca2+] pre in the presynaptic nerve terminals (boutons) on a dissociated single hippocampal rat neuron. Methods: Sprague-Dawley rats 10-14 days old were decapitated under pentobarbital anesthesia, and brain slices were prepared. The hippocampal CA1 area was touched with a fire-polished glass pipette, which vibrated horizontally, and neurons were dissociated, along with the attached presynaptic boutons. The presynaptic boutons were visualized under a confocal laser-scanning microscope after staining with FM1-43 dye, and [Ca 2+]pre was measured with acetoxymethyl ester of fluo-3 (fluo-3 AM). Results: High potassium (K+) (15-90 mM) increased the [Ca2+]pre in the Ca2+-containing solution in a concentration-dependent manner. Whereas propofol (10 μM) and pentobarbital (300 μM) suppressed the high K+ (60 mM)-induced increase in [Ca2+]pre in the boutons attached to the dendrite, they did not affect [Ca2+]pre in the boutons attached to the soma or dendrite base. As a large majority of excitatory synapses are located on dendritic spines, these agents may affect Ca2+ mobilization in the excitatory presynaptic boutons. Conclusions: Propofol and pentobarbital may affect neurotransmitter release from the excitatory presynaptic nerve terminals due to inhibition of increase in [Ca2+]pre.
AB - Purpose: Numerous reports suggest that intravenously administered (IV) anesthetics affect postsynaptic events in the central nervous system. However, there is little evidence about how general anesthetics influence the presynaptic processes. The level of presynaptic calcium (Ca2+) concentration ([Ca2+]pre) regulates neurotransmitter release. In this study, we investigated the effects of anesthetic propofol IV and the barbiturate pentobarbital on neurotransmitter release by measuring [Ca2+] pre in the presynaptic nerve terminals (boutons) on a dissociated single hippocampal rat neuron. Methods: Sprague-Dawley rats 10-14 days old were decapitated under pentobarbital anesthesia, and brain slices were prepared. The hippocampal CA1 area was touched with a fire-polished glass pipette, which vibrated horizontally, and neurons were dissociated, along with the attached presynaptic boutons. The presynaptic boutons were visualized under a confocal laser-scanning microscope after staining with FM1-43 dye, and [Ca 2+]pre was measured with acetoxymethyl ester of fluo-3 (fluo-3 AM). Results: High potassium (K+) (15-90 mM) increased the [Ca2+]pre in the Ca2+-containing solution in a concentration-dependent manner. Whereas propofol (10 μM) and pentobarbital (300 μM) suppressed the high K+ (60 mM)-induced increase in [Ca2+]pre in the boutons attached to the dendrite, they did not affect [Ca2+]pre in the boutons attached to the soma or dendrite base. As a large majority of excitatory synapses are located on dendritic spines, these agents may affect Ca2+ mobilization in the excitatory presynaptic boutons. Conclusions: Propofol and pentobarbital may affect neurotransmitter release from the excitatory presynaptic nerve terminals due to inhibition of increase in [Ca2+]pre.
UR - http://www.scopus.com/inward/record.url?scp=84859909701&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84859909701&partnerID=8YFLogxK
U2 - 10.1007/s00540-011-1186-4
DO - 10.1007/s00540-011-1186-4
M3 - Article
C2 - 21720930
AN - SCOPUS:84859909701
VL - 25
SP - 727
EP - 733
JO - Journal of Anesthesia
JF - Journal of Anesthesia
SN - 0913-8668
IS - 5
ER -