Adult-like action potential properties and abundant GABAergic synaptic responses in amygdala neurons from newborn marmosets.

The amygdala plays an important role in the processing of emotional events. This information processing is altered by development, but little is known about the development of electrophysiological properties of neurons in the amygdala. We studied the postnatal development of electrophysiological properties of neurons in the basolateral amygdala (BLA) of the common marmoset (Callithrix jacchus). Whole-cell patch-clamp recordings were obtained from BLA pyramidal neurons in brain slices prepared from developing and adult marmosets, and electrophysiological properties known to change during development in rats were analysed. Two passive electrical properties of the neuronal membrane - the input resistance (R(in)) and the membrane time constant () - significantly decreased with postnatal development. In contrast, the action potential only showed a slight decrease in duration during the first month of life, whereas the amplitude did not change after birth. Passive electrical properties and action potentials in neurons of 4-week-old marmosets were similar to those in neurons of 4-year-old marmosets. The development of the action potential duration was not correlated with the development of R(in) or , whereas the development of R(in) and was correlated with each other. Abundant spontaneous and noradrenaline-induced GABAergic currents were present immediately after birth and did not change during postnatal development. These results suggest that newborn infant marmoset BLA pyramidal neurons possess relatively mature action potentials and receive vigorous GABAergic synaptic inputs, and that they acquire adult-like electrophysiological properties by the fourth week of life.

[Simulation analysis of estimated effect-site concentrations of propofol and fentanyl administered by a TCI system for other drugs].

BACKGROUND: We experienced a case of inadequate sedation because of inappropriate use of TCI system for fentanyl. METHODS: We evaluated the blood and effect-site concentrations of propofol and fentanyl calculated by a pharmacokinetic simulation model in which the administration of one drug was managed with target-controlled infusion pump set for another drug. RESULTS: In case propofol was administered with an effect-site-steering TCI system for fentanyl, the blood concentration of propofol increased within the first few minutes, especially immediately after starting the infusion, decreased for the next 10 minutes, and then was stabilized at a level of 0.7 times the target concentration. When fentanyl was administered with a blood-steering TCI for propofol, the calculated blood concentration of fentanyl was almost equal to the target concentration in the first few minutes, and then gradually increased until reaching 2.21 times the target concentration, at 240 minutes. Furthermore, the propofol concentration and the fentanyl concentration showed small differences between the target and calculated concentrations when the infusion time was not so long. CONCLUSIONS: When the administration time is short, the anesthesiologist must be aware of the difficulty in distinguishing the human error of choosing one drug for the TCI system for another drug.

Noradrenaline-induced spontaneous inhibitory postsynaptic currents in mouse basolateral nucleus of amygdala pyramidal neurons: comparison with dopamine-induced currents.

The basolateral nucleus of the amygdala (BLA) receives both noradrenergic and dopaminergic projections. These projections are thought to be important for modulation of amygdala neural circuits. In BLA pyramidal neurons, noradrenaline (NA) is known to facilitate gamma-aminobutyric acid (GABA)ergic spontaneous inhibitory postsynaptic currents (sIPSCs) through excitation of interneurons. Dopamine (DA) also is known to facilitate GABAergic sIPSCs in pyramidal neurons of the amygdala region including the BLA. It is unclear which neurotransmitter, NA or DA, is predominant in facilitating sIPSC in the BLA. Whether NA and DA facilitate sIPSC in different or the same pyramidal neurons also remains unknown. Herein, we employed the patch clamp recording technique on BLA pyramidal neurons in mouse brain slices, and compared the facilitating actions of NA and DA on sIPSCs. First NA and then DA, or first DA and then NA, were applied to a slice. NA enhanced sIPSC frequency in the majority (80-90%) of pyramidal neurons tested, whereas DA enhanced sIPSC frequency in relatively few neurons (approximately 30%). Neurons responding to NA alone and DA alone accounted, respectively, for 54.3% and 2.9% of the pyramidal neurons tested (11.4% of neurons responded to neither NA nor DA). Pyramidal neurons in which NA and DA both facilitated sIPSCs accounted for 31.4% of neurons tested. These results suggest that NA facilitates GABAergic sIPSCs in a larger proportion of mouse BLA pyramidal neurons than DA.