Distribution of heme oxygenase-2 and NADPH-diaphorase in the spinal trigeminal nucleus of the rat

Abstract

Heme oxygenase (HO)/carbon monoxide (CO) and nitric oxide synthase (NOS)/nitric oxide (NO) systems are involved in sensory information processing. The present study was undertaken to examine the distribution of HO-2 and NOS in the spinal trigeminal nucleus (STN) of the rat, using histochemistry and immunohistochemistry. Nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) staining was found that NADPH-d activity was more prominent in the nucleus caudalis (Vc) and the dorsomedial subdivision of the nucleus oralis (Vo) than in other spinal trigeminal regions. Immunohistochemistry for HO-2 revealed that HO-2 staining neurons distributed extensively, which intensity was higher in the rostral than caudal part of the STN. The colocalization of NADPH-d and HO-2 was mainly confined in the Vc. The expression and distribution of NADPH-d and HO-2 suggest that NO and CO are likely neurotransmitters and might function in the processing orofacial signal in the STN together.

Distribution and colocalization of melatonin 1a-receptor and NADPH-d in the trigeminal system of rat

“…In the present study, we described the distribution of NADPH-d without determining which isoforms of NOS were involved. Our results agree with those from other studies (Kolesár et al, 2006; Fan et al, 2008, 2009a). It should also be noted that most of the Vc neurons involved in orofacial nociception do not synthesize NO under normal conditions, but are modulated by NO, which diffuses from adjacent NOS-positive neurons (Yeo, 2002).…”

Nicotinamide adenine dinucleotide phosphate/neuronal nitric oxide synthase‐positive neurons in the trigeminal subnucleus caudalis involved in tooth pulp nociception

“…The different degrees of intensity of OD, observed in this study with both techniques, could be considered as a relative parameter of the expression or activity of the enzyme NOS in neurons, as was previously considered by other authors (Kolesár et al,2006; Fan et al,2009). The values of OD were obtained according to the formula: OD = log (256/mean gray), and data were collected in an Excel (Microsoft) spreadsheet.…”

Carbon monoxide: A gas that modulates nociception

“…Nitric oxide (NO) is also an endogenously produced gas that can act as a second messenger molecules, which is synthesized from L‐arginine via NO synthase (NOS). The colocalization of HO‐2 and NOS has been observed in the PNS (Hedlund et al,1997; Ho et al,1999; Battish et al,2000; Fan et al,2008) and some neurons in CNS (Vincent et al,1994; Snyder et al,1998; Fan et al,2009). This suggests that the products of the two enzymes, NO and CO, might act as cotransmitters in neuronal signaling transmission.…”

“…HO‐2 is expressed abundantly in neuronal populations in spinal cord, midbrain, basal ganglia, thalamic regions, and brainstem (Vincent et al,1994; Dwyer et al,1995; Mancuso,2004; Fan et al,2008,2009), the activity of which is commonly considered when assessing neuronal activity of CO. Moreover, some investigators examine HO‐2 expression in the peripheral nervous system (PNS) of the guinea pig (Vollerthun et al,1996), the rat (Fan et al,2008), and man (Uddman et al,2004) and find numerous HO‐2‐immunoreactive cell bodies in the sensory ganglia, including trigeminal, cervical, and lumbar dorsal root ganglia.…”