Involvement of pre- and post-synaptic serotonergic receptors of dorsal raphe nucleus neural network in the control of the sweet-substance-induced analgesia in adult Rattus norvegicus (Rodentia, Muridae)

Sweet Solution Analgesia

“…One study revealed a major involvement of nicotinic cholinergic receptors in the sweet substanceinduced analgesia as atropine (cholinergic antagonist) diminished sucrose-induced analgesia [76]. Other studies have shown the involvement of noradrenaline, serotonin and their receptors in the central modulation sweet substance-induced analgesia [71,77,78].…”

Is serotonin hyperalgesic or analgesic?

“…Depending on the stimulus parameters, brainstem stimulation can cause hyperalgesia, and there is evidence that this is mediated by descending serotonergic pathways [39]. Interestingly, sweet substance-induced analgesia seems to depend partially on postsynaptic serotonin in the dorsal raphe nucleus [40]. Furthermore, an antinociceptive circuit involving ascending projections into thalamic nucleus submedius from the spinal cord seems to use 5-HT as a neurotransmitter, in addition to opioid peptides and glutamate [41].…”

Descriptive and functional neuroanatomy of locus coeruleus-noradrenaline-containing neurons involvement in bradykinin-induced antinociception on principal sensory trigeminal nucleus

“…The involvement of serotonergic and noradrenergic pathways and reticular formation nuclei in the antinociception is reported by works using many noxious stimulus-based tests, such as the tail-flick and hot plate tests (Sawynok and Reid, 1987;Coimbra et al, 1992;Coimbra and Brandão, 1997;Miyase et al, 2005;Rebouças et al, 2005;Segato et al, 2005;Freitas et al, 2005;Kishi et al, 2006;Coimbra et al, 2006), paw-withdrawal latencies (Tsuruoka and Willis, 1996), formalin test (Sajedianfard et al, 2005), percutaneous electrical foot shock (Hirata and Aston-Jones, 1994) and the electrical stimulation of dental pulp test in rats (Couto et al, 1998;Voisin et al, 2005). This last method was used in studies to demonstrate the essential participation of trigeminal nuclei, responsible for the detection of orofacial sensorial innervations originated in the dental pulp and involved in the jaw-opening reflex (Sessle, 1987;Allen et al, 1996).…”

“…Among brainstem structures involved in the activation of the endogenous pain inhibitory system (Basbaum and Fields, 1984;Fields and Basbaum, 1989), the periaqueductal gray matter (Reynolds, 1969;Dostrovsky et al, 1983;Guimarães and Prado, 1999), the raphe nuclei (Proudfit, 1980;Clark and Proudfit, 1991;Rosa et al, 1998;Bitner et al, 1998;Prado and Faganelllo, 2000;Lu et al, 2004;Miyase et al, 2005) and the locus coeruleus (LC), as well as the subcoeruleus area have been reported as important structures (Hu et al, 1986;Proudfit and Clark, 1991;Tsuruoka et al, 2003;Freitas et al, 2005).…”