Fig. 1

Identification of LC neurons in LC slices. a Locus coeruleus nucleus was identified under infra-red microscopy as a dense and compact group of cells and translucent area lying on the ventrolateral margin of the 4th ventricle (bright areas). The LC neurons were prepared in a horizontal brainstem slice from a 14 to 21-day-old rat. b Representative samples showing intracellular recordings of identified LC neurons with the mean spontaneous activity of LC neurons of morphine-treated rats (0.2–4 Hz), resting membrane potential (− 51 ± 1.8 mV), and rhythmic oscillations. Representative traces of currents recorded from LC slices of the morphine-treated rats