Lateral hypothalamic-induced antinociception may be mediated by a substance P connection with the rostral ventromedial medulla

Differences in carbachol dose, pain condition, and sex following lateral hypothalamic stimulation

“…However, there is evidence that neuropathic pain, including hyperalgesic pain states, creates a shift from opioid mediated responses to noradrenergic-mediated mechanisms (Hartrick, 2012; Rojo et al, 2012; Schiene et al, 2011; Schroder et al, 2010). This finding is in line with recent reports from our laboratory and others that the LH modifies nociception in the spinal cord dorsal horn in part through descending alpha adrenergic brainstem neurons (Holden and Naleway, 2001; Holden et al, 2002; Holden et al, 2005; Holden and Pizzi 2008; Holden et al, 2009; Safari et al, 2009) and supports the hypothesis that LH stimulation will modify both nociceptive and neuropathic pain in male and female rats.…”

“…Both electrical (Lopez and Cox,1992; Dafny et al,1996; Franco and Prado, 1996) and chemical stimulation with S -glutamate (Behbehani et al, 1988), morphine (Dafny et al, 1996; Franco and Prado, 1996), carbamylcholine (carbachol; Holden & Naleway, 2001; Holden et al, 2002; Holden et al, 2005; Holden and Pizzi, 2008; Holden et al, 2009; Safari et al, 2009), or nociception/orphanin FQ (Gerashchenko et al, 2011;) increase response latencies to acute (nociceptive) pain in rats. This nociceptive modulation was found in both male (Dafny et al, 1996; Franco and Prado, 1996; Behbehani et al, 1988; Safari et al, 2009; Gerashchenko et al, 2011) and female rats (Lopez and Cox, 1992; Holden and Naleway, 2001; Holden et al, 2002; Holden et al, 2005; Holden and Pizzi, 2008; Holden et al, 2009). The role of the LH in modulating neuropathic pain states is not known for either male or female rats.…”

Effects of neurokinin-1 receptor agonism and antagonism in the rostral ventromedial medulla of rats with acute or persistent inflammatory nociception

“…Finally, microinjection of the NK1 receptor agonist GF73632 in the ventral tegmental area or the nucleus accumbens suppresses flinching in the formalin test (Altier and Stewart, 1997). Studies with neurokinin-1 (NK1) receptor antagonists have further established the antinociceptive action of endogenously released Sub P. Microinjection of RP-8950 in the ventral tegmental area antagonizes foot shock stress-induced antinociception (Altier and Stewart, 1999), while microinjection of L-703,606 in the rostral ventromedial medulla (RVM) or the PAG reverses the antinociception produced by microinjection of carbachol in the lateral hypothalamus (Holden and Pizzi, 2008; Holden et al, 2009). …”

The diagonal band of Broca is involved in the pressor pathway activated by noradrenaline microinjected into the periaqueductal gray area of rats

“…Cobalt is an inorganic calcium channel blocking agent used to suppress Ca 2+ -induced synaptic transmission (Kretz 1984). Microinjection of cobalt chloride (CoCl 2 ) has been used for the reversible inactivation of brain nuclei, in order to understand their functional role (Deolindo et al 2008;Ciriello et al 2008;Holden and Pizzi 2008;Pelosi et al 2007;Cavun and Millington 2001;Boscan and Paton 2001;Fisk and Wyss 2000). Cobalt is an inorganic calcium channel blocker used to suppress Ca 2+ -induced synaptic transmission (Kretz 1984).…”