Sivakami Haug - Academia.edu (original) (raw)

Papers by Sivakami Haug

Research paper thumbnail of Delta (δ) opioid receptors in small and medium-sized trigeminal neurons supporting the dental pulp of rats

Archives of Oral Biology, 2006

The control of pain perception is a challenge in clinical dentistry, most prominent during tooth ... more The control of pain perception is a challenge in clinical dentistry, most prominent during tooth pulp inflammation. The tooth pulp is a well-defined target, and is densely supplied by a sensory trigeminal innervation. Opioids are signaling molecules that are suggested to participate in pain perception. Here we analysed the presence of d opioid receptor (DOR) in trigeminal neurons innervating the tooth pulp of rat molars. Immunohistochemical and ultrastructural analysis revealed that DOR was identified in peripheral nerves in the molar dental pulp, both in the root and the coronal pulpal parts, with branching in the highly innervated subodontoblast layer. DOR was localised in about one third of all the trigeminal dental neurons, identified by means of retrograde neuronal transport of fluorogold (FG) from the dental pulp. Of the DOR-labeled neurons, nearly all were small and medium-sized (147.5-1810.2 mm 2 , mean 749.1 AE 327.3 mm 2 ). Confocal microscopy confirmed that DORimmunoreactivity was distributed as granules in the neuronal cytoplasm. Approximately 70% of the DOR-immunoreactive neurons were also immunopositive for vanilloid receptor 1 (TRPV1). Ultrastructural analysis demonstrated DOR-immunoreactivity in the unmyelinated and in some of the myelinated nerve fibers in the dental pulp. These results indicate that DOR may influence the function in a subset of small and medium-sized trigeminal sensory neurons supporting the tooth, which are mainly known for their ability to mediate nociceptive stimuli. Agonists, acting on DOR, may thus have an influence on a subpopulation of nociceptive neurons supporting the rat tooth. #

Research paper thumbnail of IL-1α and TNF-α Expression in Rat Periapical Lesions and Dental Pulp after Unilateral Sympathectomy

Neuroimmunomodulation, 2004

Apical periodontitis is an inflammatory disease characterized by bone resorption, and sympathetic... more Apical periodontitis is an inflammatory disease characterized by bone resorption, and sympathetic nerves are known to modulate bone resorption and bone remodeling. Higher numbers of osteoclasts and larger periapical lesions have been observed after sympathectomy in rats, but the mechanisms underlying the inhibitory effect of sympathetic nerves on osteoclasts are unknown. This study aimed to test the hypothesis that sympathetic nerves inhibit the production of the bone-resorbing pro-inflammatory cytokines IL-1 alpha and TNF-alpha in rat periapical lesions. Rats were unilaterally sympathectomized and apical lesions were induced by exposing the dental pulp of molar teeth to the oral microflora. We quantified the cytokines IL-1 alpha and TNF-alpha by enzyme-linked immunosorbent assay, and immunohistochemical analysis was done for qualitative localization. Pulp from intact incisor teeth was tested as a control. We showed that IL-1 alpha was increased, but not TNF-alpha, in the periapical lesions on the sympathectomized side. Both IL-1 alpha and TNF-alpha were expressed in unexposed pulp. TNF-alpha was significantly decreased in the denervated incisor pulp, whereas the level of IL-1 alpha remained unchanged. This study suggests that sympathetic nerves have an inhibitory effect on IL-1 alpha in periapical lesions and a stimulatory effect on TNF-alpha in the intact rat pulp.

Research paper thumbnail of High interstitial fluid pressure in rat tongue cancer is related to increased lymph vessel area, tumor size, invasiveness and decreased body weight

Journal of Oral Pathology & Medicine, 2007

BACKGROUND: Interstitial fluid pressure (IFP) in most tumors is high, and this high pressure has ... more BACKGROUND: Interstitial fluid pressure (IFP) in most tumors is high, and this high pressure has been correlated with poor prognosis. Measurements of IFP in normal tongue and in tongue cancer are lacking. Recent research suggests the existence of a relationship between increased peritumoral lymph vessels (PTLV) and survival, and a correlation of increased lymphatic vessel density with an unfavorable prognosis has been reported. MATERIALS AND METHODS: In the present study, tongue squamous cell carcinoma (SCC) was induced by adding the carcinogen 4-nitroquinoline oxide in drinking water for 19 weeks. The IFP was measured by micropuncture and immunohistochemistry was used to visualize lymph vessels. RESULTS: In normal tongue, IFP averaged 3.1 ± 0.3 mmHg. The IFP, both in the tumor (29.1 ± 2.9 mmHg) and 0.5 cm anterior to it (15.4 ± 2.1 mmHg) was consistently increased (P < 0.005) with values ranging from 10 to 40 mmHg. The highest IFP values were measured in rats with large tumors (P < 0.05) and low body weight (P < 0.001), suggesting that IFP increases with cancer progression. Lymphatic vessel area (%), as determined with the lymphatic specific marker LYVE-1 antibody, was significantly increased in the peritumoral area when compared to intratumoral and control mucosa (P < 0.05). There was a significant positive correlation between IFP, PTLV area, tumor size and invasiveness. CONCLUSIONS: Our data show that IFP is increased in tongue cancer. Corresponding changes in PTLV area, invasiveness, tumor area and IFP suggest that the increased pressure is caused by defective lymph drainage and solid stress generated by tumor cells growing in a low compliant environment. Raju et al. 138 J Oral Pathol Med Tissue pressure in rat tongue cancer Raju et al. 143 J Oral Pathol Med Tissue pressure in rat tongue cancer Raju et al.

Research paper thumbnail of The Effect of Unilateral Sympathectomy and Cavity Preparation on Peptidergic Nerves and Cells in Rat Dental Pulp

Experimental Neurology, 2001

The effect of unilateral removal of the superior cervical ganglion on the innervation pattern of ... more The effect of unilateral removal of the superior cervical ganglion on the innervation pattern of nerve fibers immunoreactive (IR) to calcitonin gene-related peptide (CGRP), substance P (SP), and neuropeptide Y (NPY), as well as the occurrence of cells in the injured and uninjured rat molar pulp, was investigated. Light microscopic immunocytochemistry demonstrated that the molar pulps contralateral to the sympathectomy contained a NPY-IR nerve fiber network more dense and heavily stained than unoperated control rats. The NPY-IR fibers showed, however, no sprouting after deep cavity preparation. There was no compensatory increase in CGRP-and SP-IR nerve fibers in the dental pulp after unilateral sympathectomy, although a significant increase in cells IR to CGRP and SP was found in the ipsilateral trigeminal ganglion. Unilateral sympathectomy induced a significant increase in cell density both in the inflamed and in the uninflamed dental pulp bilaterally. Our results demonstrate, for the first time, a trophic effect of the sympathetic nerves on cells in the dental pulp, indicating that an imbalance of sympathetic nerves may induce inflammation and pain in teeth.

Research paper thumbnail of Sympathectomy suppresses tumor growth and alters gene-expression profiles in rat tongue cancer

European Journal of Oral Sciences, 2009

Research paper thumbnail of Characterization of the dental lymphatic system and identification of cells immunopositive to specific lymphatic markers

European Journal of Oral Sciences, 2009

Research paper thumbnail of Identification of a Ca2+-Sensing Receptor in Rat Trigeminal Ganglia, Sensory Axons, and Tooth Dental Pulp

Calcified Tissue International, 2008

Extracellular Ca 2+ regulates dentin formation, but little information is available on this regul... more Extracellular Ca 2+ regulates dentin formation, but little information is available on this regulatory mechanism. We have previously reported that sensory denervation reduces dentin formation, suggesting a role for sensory nerves in tooth mineralization. The G proteincoupled Ca 2+ -sensing receptor (CaR) is expressed in dorsal root ganglia and perivascular sensory nerves in mesenteric arterioles, and activation of these receptors by Ca 2+ has been shown to induce vascular relaxation. The present study determined CaR expression in tooth dental pulp (DP), sensory axons, and trigeminal ganglion (TG) as well as the effect of increased [Ca 2+ ] e or a calcimimetic on tooth blood flow. The distribution of CaR, studied by immunochemistry, RT-PCR, and Western blot, indicates abundant expression of CaR in sensory axons in the jaws, TG, and DP. Restriction analysis of PCR products with specific endonucleases showed the presence of CaR message in TG and DP, and Western blotting indicates the expression of mature and immature forms of the receptor in these tissues. Pulpal blood flow, measured by laser-Doppler flowmetry, increased by 67% ± 6% (n = 12) following receptor stimulation with 5 mM Ca 2+ , which was completely inhibited by 5 lM IBTx, a high-conductance K Ca channel blocker indicating a mechanism involving hyperpolarization. NPS R-467 (10 lM) increased blood flow by 85% ± 18% (n = 6), suggesting regulation through the CaR. Our results suggest that the CaR is present in sensory nerves, DP, and TG and that an increase in Ca 2+ in the DP causes vasodilatation, which may contribute to accumulation of Ca 2+ during dentin mineralization.

Research paper thumbnail of Effect of electrical tooth stimulation on blood flow and immunocompetent cells in rat dental pulp after sympathectomy

Acta Odontologica Scandinavica - ACTA ODONTOL SCAND, 2004

Previous experiments show that nerves have effect on the emigration of immunocompetent cells duri... more Previous experiments show that nerves have effect on the emigration of immunocompetent cells during acute neurogenic inflammation. The present study aims to determine whether the sympathetic or sensory nerves are responsible for emigration of CD43+ and I-A antigen-expressing cells in the dental pulp after electrical tooth stimulation. Wistar rats were used. Experimental rats (n = 6) had the right superior cervical ganglion removed (SCGx), whereas control rats (n = 6) had sham surgery. Fourteen days later, electrical stimulation of the right maxillary 1st molar was performed in both groups for 20-25 s every 5th min for a total period of 4 h. Changes in pulpal blood flow (PBF) were recorded with a laser Doppler flowmeter. All rats were transcardiacally perfused and processed for immunohistochemistry using antibodies against neuropeptides and immune cells. Intermittent electrical stimulation consistently increased PBF and depleted sympathetic and sensory neuropeptides in the dental pulp. The increase in PBF gradually decreased and approached control values at the end of the 4 h stimulation period. A significant increase in the number of I-A antigen-expressing dendritic cells was found in both the SCGx (P &amp;amp;amp;amp;lt; 0.001) and control rats (P &amp;amp;amp;amp;lt; 0.007). In contrast, tooth stimulation did not increase the number of CD43+ cells in the SCGx rats compared to the unstimulated contralateral control molar. Significantly more CD43+ PMN cells (P &amp;amp;amp;amp;lt; 0.01) were found in the control rats after stimulation. It is concluded that stimulation of sympathetic nerves causes recruitment of CD43+ PMN cells, whereas stimulation of sensory nerves causes emigration of I-A antigen-expressing dendritic cells in the dental pulp.

Research paper thumbnail of Delta (δ) opioid receptors in small and medium-sized trigeminal neurons supporting the dental pulp of rats

Archives of Oral Biology, 2006

The control of pain perception is a challenge in clinical dentistry, most prominent during tooth ... more The control of pain perception is a challenge in clinical dentistry, most prominent during tooth pulp inflammation. The tooth pulp is a well-defined target, and is densely supplied by a sensory trigeminal innervation. Opioids are signaling molecules that are suggested to participate in pain perception. Here we analysed the presence of d opioid receptor (DOR) in trigeminal neurons innervating the tooth pulp of rat molars. Immunohistochemical and ultrastructural analysis revealed that DOR was identified in peripheral nerves in the molar dental pulp, both in the root and the coronal pulpal parts, with branching in the highly innervated subodontoblast layer. DOR was localised in about one third of all the trigeminal dental neurons, identified by means of retrograde neuronal transport of fluorogold (FG) from the dental pulp. Of the DOR-labeled neurons, nearly all were small and medium-sized (147.5-1810.2 mm 2 , mean 749.1 AE 327.3 mm 2 ). Confocal microscopy confirmed that DORimmunoreactivity was distributed as granules in the neuronal cytoplasm. Approximately 70% of the DOR-immunoreactive neurons were also immunopositive for vanilloid receptor 1 (TRPV1). Ultrastructural analysis demonstrated DOR-immunoreactivity in the unmyelinated and in some of the myelinated nerve fibers in the dental pulp. These results indicate that DOR may influence the function in a subset of small and medium-sized trigeminal sensory neurons supporting the tooth, which are mainly known for their ability to mediate nociceptive stimuli. Agonists, acting on DOR, may thus have an influence on a subpopulation of nociceptive neurons supporting the rat tooth. #

Research paper thumbnail of IL-1α and TNF-α Expression in Rat Periapical Lesions and Dental Pulp after Unilateral Sympathectomy

Neuroimmunomodulation, 2004

Apical periodontitis is an inflammatory disease characterized by bone resorption, and sympathetic... more Apical periodontitis is an inflammatory disease characterized by bone resorption, and sympathetic nerves are known to modulate bone resorption and bone remodeling. Higher numbers of osteoclasts and larger periapical lesions have been observed after sympathectomy in rats, but the mechanisms underlying the inhibitory effect of sympathetic nerves on osteoclasts are unknown. This study aimed to test the hypothesis that sympathetic nerves inhibit the production of the bone-resorbing pro-inflammatory cytokines IL-1 alpha and TNF-alpha in rat periapical lesions. Rats were unilaterally sympathectomized and apical lesions were induced by exposing the dental pulp of molar teeth to the oral microflora. We quantified the cytokines IL-1 alpha and TNF-alpha by enzyme-linked immunosorbent assay, and immunohistochemical analysis was done for qualitative localization. Pulp from intact incisor teeth was tested as a control. We showed that IL-1 alpha was increased, but not TNF-alpha, in the periapical lesions on the sympathectomized side. Both IL-1 alpha and TNF-alpha were expressed in unexposed pulp. TNF-alpha was significantly decreased in the denervated incisor pulp, whereas the level of IL-1 alpha remained unchanged. This study suggests that sympathetic nerves have an inhibitory effect on IL-1 alpha in periapical lesions and a stimulatory effect on TNF-alpha in the intact rat pulp.

Research paper thumbnail of High interstitial fluid pressure in rat tongue cancer is related to increased lymph vessel area, tumor size, invasiveness and decreased body weight

Journal of Oral Pathology & Medicine, 2007

BACKGROUND: Interstitial fluid pressure (IFP) in most tumors is high, and this high pressure has ... more BACKGROUND: Interstitial fluid pressure (IFP) in most tumors is high, and this high pressure has been correlated with poor prognosis. Measurements of IFP in normal tongue and in tongue cancer are lacking. Recent research suggests the existence of a relationship between increased peritumoral lymph vessels (PTLV) and survival, and a correlation of increased lymphatic vessel density with an unfavorable prognosis has been reported. MATERIALS AND METHODS: In the present study, tongue squamous cell carcinoma (SCC) was induced by adding the carcinogen 4-nitroquinoline oxide in drinking water for 19 weeks. The IFP was measured by micropuncture and immunohistochemistry was used to visualize lymph vessels. RESULTS: In normal tongue, IFP averaged 3.1 ± 0.3 mmHg. The IFP, both in the tumor (29.1 ± 2.9 mmHg) and 0.5 cm anterior to it (15.4 ± 2.1 mmHg) was consistently increased (P < 0.005) with values ranging from 10 to 40 mmHg. The highest IFP values were measured in rats with large tumors (P < 0.05) and low body weight (P < 0.001), suggesting that IFP increases with cancer progression. Lymphatic vessel area (%), as determined with the lymphatic specific marker LYVE-1 antibody, was significantly increased in the peritumoral area when compared to intratumoral and control mucosa (P < 0.05). There was a significant positive correlation between IFP, PTLV area, tumor size and invasiveness. CONCLUSIONS: Our data show that IFP is increased in tongue cancer. Corresponding changes in PTLV area, invasiveness, tumor area and IFP suggest that the increased pressure is caused by defective lymph drainage and solid stress generated by tumor cells growing in a low compliant environment. Raju et al. 138 J Oral Pathol Med Tissue pressure in rat tongue cancer Raju et al. 143 J Oral Pathol Med Tissue pressure in rat tongue cancer Raju et al.

Research paper thumbnail of The Effect of Unilateral Sympathectomy and Cavity Preparation on Peptidergic Nerves and Cells in Rat Dental Pulp

Experimental Neurology, 2001

The effect of unilateral removal of the superior cervical ganglion on the innervation pattern of ... more The effect of unilateral removal of the superior cervical ganglion on the innervation pattern of nerve fibers immunoreactive (IR) to calcitonin gene-related peptide (CGRP), substance P (SP), and neuropeptide Y (NPY), as well as the occurrence of cells in the injured and uninjured rat molar pulp, was investigated. Light microscopic immunocytochemistry demonstrated that the molar pulps contralateral to the sympathectomy contained a NPY-IR nerve fiber network more dense and heavily stained than unoperated control rats. The NPY-IR fibers showed, however, no sprouting after deep cavity preparation. There was no compensatory increase in CGRP-and SP-IR nerve fibers in the dental pulp after unilateral sympathectomy, although a significant increase in cells IR to CGRP and SP was found in the ipsilateral trigeminal ganglion. Unilateral sympathectomy induced a significant increase in cell density both in the inflamed and in the uninflamed dental pulp bilaterally. Our results demonstrate, for the first time, a trophic effect of the sympathetic nerves on cells in the dental pulp, indicating that an imbalance of sympathetic nerves may induce inflammation and pain in teeth.

Research paper thumbnail of Sympathectomy suppresses tumor growth and alters gene-expression profiles in rat tongue cancer

European Journal of Oral Sciences, 2009

Research paper thumbnail of Characterization of the dental lymphatic system and identification of cells immunopositive to specific lymphatic markers

European Journal of Oral Sciences, 2009

Research paper thumbnail of Identification of a Ca2+-Sensing Receptor in Rat Trigeminal Ganglia, Sensory Axons, and Tooth Dental Pulp

Calcified Tissue International, 2008

Extracellular Ca 2+ regulates dentin formation, but little information is available on this regul... more Extracellular Ca 2+ regulates dentin formation, but little information is available on this regulatory mechanism. We have previously reported that sensory denervation reduces dentin formation, suggesting a role for sensory nerves in tooth mineralization. The G proteincoupled Ca 2+ -sensing receptor (CaR) is expressed in dorsal root ganglia and perivascular sensory nerves in mesenteric arterioles, and activation of these receptors by Ca 2+ has been shown to induce vascular relaxation. The present study determined CaR expression in tooth dental pulp (DP), sensory axons, and trigeminal ganglion (TG) as well as the effect of increased [Ca 2+ ] e or a calcimimetic on tooth blood flow. The distribution of CaR, studied by immunochemistry, RT-PCR, and Western blot, indicates abundant expression of CaR in sensory axons in the jaws, TG, and DP. Restriction analysis of PCR products with specific endonucleases showed the presence of CaR message in TG and DP, and Western blotting indicates the expression of mature and immature forms of the receptor in these tissues. Pulpal blood flow, measured by laser-Doppler flowmetry, increased by 67% ± 6% (n = 12) following receptor stimulation with 5 mM Ca 2+ , which was completely inhibited by 5 lM IBTx, a high-conductance K Ca channel blocker indicating a mechanism involving hyperpolarization. NPS R-467 (10 lM) increased blood flow by 85% ± 18% (n = 6), suggesting regulation through the CaR. Our results suggest that the CaR is present in sensory nerves, DP, and TG and that an increase in Ca 2+ in the DP causes vasodilatation, which may contribute to accumulation of Ca 2+ during dentin mineralization.

Research paper thumbnail of Effect of electrical tooth stimulation on blood flow and immunocompetent cells in rat dental pulp after sympathectomy

Acta Odontologica Scandinavica - ACTA ODONTOL SCAND, 2004

Previous experiments show that nerves have effect on the emigration of immunocompetent cells duri... more Previous experiments show that nerves have effect on the emigration of immunocompetent cells during acute neurogenic inflammation. The present study aims to determine whether the sympathetic or sensory nerves are responsible for emigration of CD43+ and I-A antigen-expressing cells in the dental pulp after electrical tooth stimulation. Wistar rats were used. Experimental rats (n = 6) had the right superior cervical ganglion removed (SCGx), whereas control rats (n = 6) had sham surgery. Fourteen days later, electrical stimulation of the right maxillary 1st molar was performed in both groups for 20-25 s every 5th min for a total period of 4 h. Changes in pulpal blood flow (PBF) were recorded with a laser Doppler flowmeter. All rats were transcardiacally perfused and processed for immunohistochemistry using antibodies against neuropeptides and immune cells. Intermittent electrical stimulation consistently increased PBF and depleted sympathetic and sensory neuropeptides in the dental pulp. The increase in PBF gradually decreased and approached control values at the end of the 4 h stimulation period. A significant increase in the number of I-A antigen-expressing dendritic cells was found in both the SCGx (P &amp;amp;amp;amp;lt; 0.001) and control rats (P &amp;amp;amp;amp;lt; 0.007). In contrast, tooth stimulation did not increase the number of CD43+ cells in the SCGx rats compared to the unstimulated contralateral control molar. Significantly more CD43+ PMN cells (P &amp;amp;amp;amp;lt; 0.01) were found in the control rats after stimulation. It is concluded that stimulation of sympathetic nerves causes recruitment of CD43+ PMN cells, whereas stimulation of sensory nerves causes emigration of I-A antigen-expressing dendritic cells in the dental pulp.