Changes in serotonin in rat brain during slow-wave sleep and paradoxical sleep: application of the microwave fixation method to sleep research tech./dosim.

To study changes in serotonin (5-HT) and its metabolite 5-hydroxyindole acetic acid (5-HIAA) in rat brain during slow-wave sleep and paradoxical sleep.

The microwave fixation method was applied. Rats were sacrified by microwave irradiation of the head (2450 MHz, 5 kW, 2.0 sec) after 10 min of slow-wave sleep or wakefulness or paradoxical sleep.

• animal
• rat/Wistar
• partial body: head

Since the polygraphic records did not change just before exposure and the brains were fixed within 2 sec., the authors concluded that their procedure seems to be better for fixation of the brain at various states of sleep and wakefulness than previous methods (such as KCl injection or brain biopsy). Serotonin content was higher in the cerebral cortex and midbrain during both phases of sleep than during wakefulness.The 5-HIAA content in the hippocampus was higher during slow-wave sleep than during wakefulness. Similar tendencies were revealed in other regions, but not statistically significant. The 5-HIAA content to the cerebral cortex, hippocampus, midbrain and pons and medulla oblongata were lower during paradoxical sleep than during slow-wave sleep.