S. Mihailescu et al., Nicotine stimulation of dorsal raphe neurons: effects on laterodorsal and pedunculopontine neurons, EUR NEUROPS, 11(5), 2001, pp. 359-366
Previous studies showed that nicotine suppresses the ponto-geniculo-occipit
al (PGO) spikes of rapid eye movement (REM) sleep in cats. This effect may
depend on stimulation of dorsal raphe nucleus (DRN) serotoninergic neurons
that inhibit the pedunculopontine (PPT) and laterodorsal tegmental (LDT) ch
olinergic neurons, generators of PGO spikes. For testing this hypothesis 37
experiments were performed in rat midbrain slices. Nicotine (2 mM), admini
stered locally into DRN. significantly increased the firing rate of 81.1% D
RN neurons and serotonin release while simultaneously and significantly dec
reasing the firing rate of 80.8% LDT neurons and of 81.8% PPT neurons. The
inhibition of LDT neurons by nicotine administered into DRN was blocked by
the 5-HT1A receptor antagonist WAY-100635 (140 nM) administered into LDT. T
hese results indicate that nicotine inhibits the activity of LDT and PPT ne
urons and consequently the generation of PGO spikes through stimulation of
DRN serotoninergic neurons. (C) 2001 Elsevier Science B.V. All rights reser
ved.