Table 1.
Neuromodulators of CN.
| Neuromodulator | Source | Receptors | Known effects |
|---|---|---|---|
| 5-HT | GiC, PnO (Bishop and Ho, 1985). | 5-HT1B (might be expressed by PCs axons) 5-HT1C,5-HT2A, 5-HT2B (Might be expressed only in IN) 5-HT3 (low levels), 5-HT5A (Choi and Maroteaux, 1996; Kia et al., 1996; Sari et al., 1999; Geurts et al., 2002). | In vitro |
| Attenuates the HCN current and decreases the amplitude of IPSCs by a presynaptic mechanism (Saitow et al., 2009). Increases the firing rate and reduces the response to glutamate via a postsynaptic mechanism (Gardette et al., 1987). | |||
| In vivo | |||
| 5-HT1A and 5-HT2 agonists induce a decrease in firing rate and 5-HT5A agonist increase firing rate (Di Mauro et al., 2003). In other studies only decreases in firing rate and response to glutamate, were documented (Kitzman and Bishop, 1997). Neurons excited by 5-HT were located at cerebellar nuclei projecting to the thalamus and cortex, whereas the nuclei projecting to peripheral motor centers reduced their firing rate when levels of 5-HT increased (Di Mauro et al., 2003). | |||
| NE | LC (Hokfelt and Fuxe, 1969; Somana and Walberg, 1978). | In vivo | |
| Direct application of NE decreases the firing rate of neurons in all nuclei (Di Mauro et al., 2003). | |||
| Decreases response to application of GABA in the FN and Posterior IN while increasing it in the anterior IN. The LN has mixed responses (Di Mauro et al., 2012). | |||
| Ach | Vestibular nuclei (non-beaded fibers) PTg, GiC and Raphe nuclei (beaded fibers creating a dense network) (Jaarsma et al., 1997). | ||
| Dopamine | But source of dopamine is unknown as nuclei is innervated by non-dopaminergic neurons from the VTA (Ikai et al., 1992). | DAT presence is demonstrated (Delis et al., 2004, 2008). | |
| Histamine | TMN (Haas and Panula, 2003). | H1, H2 (Qin et al., 2011) and H3 (mRNA in FN and IN) (Pillot et al., 2002). | In vitro |
| Increases firing rate of neurons in all of the CN, probably through H2 activation (Shen et al., 2002; Tang et al., 2008; Qin et al., 2011). | |||
| Orexin | PeFLH (Peyron et al., 1998). | OX1R, OX2R (Hervieu et al., 2001; Cluderay et al., 2002). | In vitro |
| Increases firing rate of neurons in the IN probably through OX2R activation (Yu et al., 2010). |