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L-C Yang

Publications and source records attributed to L-C Yang.

At least 19 recordsLinked to original sources
PubMed2006

Livedoid vasculopathy: long-term follow-up results following hyperbaric oxygen therapy.

BACKGROUND: Livedoid vasculopathy, also known as atrophie blanche, is a recurrent painful vasculopathy appearing mostly on the lower limbs. Treatment is challenging and relapses are frequent. OBJECTIVES: To analyse the long-term effect and safety of hyperbaric oxygen (HBO) therapy in treating livedoid vasculopathy. METHODS: Twelve patients with active livedoid vasculopathy were included in this study. All patients underwent HBO therapy five times a week. Each week photographs were taken and the total dose of analgesics was recorded. Side-effects were documented and assessed. Recurrence was defined as the presence of skin ulceration. RESULTS: Of the eight patients who completed the treatment, resumption of ambulation and reduction of analgesics were achieved at an average of 4.9 HBO therapy sessions. Leg ulcers in all eight patients healed completely at a mean of 3.4 weeks (range 2-5 weeks). Six patients suffered relapses of ulceration and responded to additional HBO therapy. No significant side-effects were found. CONCLUSIONS: HBO is a relatively safe, fast and effective method to treat patients with livedoid vasculopathy.

Adolescent↗
PubMed2006

Association of mu-opioid receptor gene polymorphism (A118G) with variations in morphine consumption for analgesia after total knee arthroplasty.

BACKGROUND: Morphine consumption after a given surgical procedure can vary considerably. Studies show that single nucleotide polymorphism involving the nucleotide position 118 at exon 1 of the mu-opioid receptor gene (OPRM1) may play a role in mediating the effects of opioids. This study was performed to correlate the A118G polymorphism at OPRM1 with morphine consumption in patients undergoing total knee arthroplasty. METHODS: Post-operative pain was relieved by patient-controlled analgesia (PCA). The analgesic effect was evaluated using a visual analogue scale. Side-effects, such as sedation, nausea and vomiting, and pruritus, were recorded systematically. The genotypes were determined by sequencing polymerase chain reaction-amplified DNA. The differences in demographics and consumed morphine from the PCA device between the different genotypes were tested using one-way analysis of variance. The prevalence of side-effects from morphine and sex distribution were compared using the Kruskal-Wallis test. RESULTS: One hundred and forty-seven patients were included in the study. Twenty-seven patients who required rescue analgesia were excluded; these patients did not differ demographically or genetically from the 120 who completed the study. Of the latter, 74 were A118 homozygous (AA), 33 were heterozygous (AG) and 13 were G118 homozygous (GG). Group GG consumed significantly more morphine (40.4 +/- 22.0 mg) than group AA (25.3 +/- 15.5 mg) and group AG (25.6 +/- 11.7 mg) during the first 48 h post-operatively. The groups did not differ with respect to reported pain, age, sex, weight and adverse effects. CONCLUSIONS: G118 homozygotes have a poorer response to morphine for post-operative pain control than A118 homozygotes or heterozygotes. The genotype may thus influence the post-operative response to pain and cause differences in the amounts of analgesic consumed by patients after total knee arthroplasty.

Aged↗
PubMed2005

Gene gun particle encoding preproenkephalin cDNA produces analgesia against capsaicin-induced bladder pain in rats.

OBJECTIVES: To evaluate the efficacy of gene therapy using a gene gun or direct injection for the transfer of human preproenkephalin (PPE) plasmid cDNA using a capsaicin-induced bladder pain model in rats. Opioid peptides play an essential role in the modulation of micturition reflex and control of inflammatory pain. PPE is one such precursor molecule. METHODS: Human PPE cDNA was cloned into a modified pCMV plasmid and delivered into the bladder wall of adult female rats by direct injection or gene gun. At 4 and 7 days after gene therapy, continuous cystometrograms were performed under urethane anesthesia by filling the bladder (0.08 mL/min) with saline, followed by 15 muM capsaicin. Immunohistochemical staining was used to detect enkephalins in the bladder after PPE cDNA transfer. RESULTS: The intercontraction interval was decreased after intravesical instillation of capsaicin (65.0% and 63.1% decrease) in the control group or direct PPE gene injection group, respectively. However, the gene gun-treated group showed a significantly reduced response to capsaicin instillation at day 4 and day 7 (intercontraction interval 16.2% and 42.8% decrease, respectively). This analgesic effect was reversed by intravenous naloxone, an opioid antagonist (5 mg/kg). Increased enkephalin immunoreactivity in the bladder was observed in the gene gun-treated group at day 4, which was reduced at day 7. CONCLUSIONS: The PPE gene can be effectively transferred and suppress the nociceptive response in the bladder using the gene gun method. These results support potential clinical application of PPE gene gun delivery system for the treatment of bladder pain and other types of visceral pain.

Analgesia↗
PubMed2005

Gene knockdown with intrathecal siRNA of NMDA receptor NR2B subunit reduces formalin-induced nociception in the rat.

N-methyl-D-aspartate (NMDA) receptor activation, at the level of the spinal cord, has been shown to play an important role in the facilitation of nociception in several animal models. However, the use of NMDA antagonists as analgesics is limited by serious side effects due to nonselective effects among the NMDA receptor subtypes. Recent discoveries revealed that the transfection of small interfering RNAs (siRNAs) into animal cells resulted in the potent, long-lasting, post-transcriptional silencing of specific genes. Thus, we investigated the effect of intrathecal (i.t.) injection of siRNAs targeting NMDA-R2B receptor subunit protein (NR2B) receptors, a subunit of NMDA receptor, for the modulation of pain. The results indicate that the use of siRNA targeting the NR2B subunit not only decreased the expression of NR2B mRNA and its associated protein, as demonstrated by real-time PCR and Western blotting, but also abolished formalin-induced pain behaviors in rat model. The peak effect occurred on day 3 for mRNA and day 7 for its protein, following i.t. injection of 5 microg of siRNA-NR2B. These data prove the feasibility of i.t. siRNAs in the investigation of functional gene expression in the context of whole animal behavior for the management of chronic pain.

Animals↗
PubMed2005

Peripheral B lymphocyte beta1,3-galactosyltransferase and chaperone expression in immunoglobulin A nephropathy.

PURPOSE: Aberrant O-glycosylation of serum IgA(1) is presumed to be one of the main pathogenesis of immunoglobulin A nephropathy (IgAN). beta1,3-galactosyltransferase (beta1,3GT), whose activity requires coexistence of a specific chaperone, is the main enzyme which participate in the glycosylation process. The current study was carried out to elucidate the expression level of beta1,3GT (C1GALT1) and its chaperone (Cosmc) in IgAN, and their relationships with clinical features as well as IgA glycosylation level. DESIGN, SETTING AND SUBJECTS: Forty-one patients with IgAN, 21 patients with non-IgAN glomerulonephritis and 26 normal controls were included in the present study. Peripheral B lymphocytes were isolated, and then expression level of C1GALT1 and Cosmc were quantitatively measured by real-time reverse transcriptase polymerase chain reaction (RT-PCR). Serum IgA level and glycosylation level were determined by enzyme-linked immunosorbent assay (ELISA) and VV lectin-binding method. Correlation analysis was performed between C1GALT1/Cosmc expression levels and clinical manifestations (severe proteinuria, renal dysfunction, gross haematuria). RESULTS: B-lymphocyte Cosmc gene expression level was significantly lower in IgAN patients than that of normal control and non-IgAN patients (P<0.05), whilst no apparent disparity was observed in C1GALT1 expression level. Cosmc expression showed a negative correlation with IgA O-glycosylation level indicated by VV lectin-binding assay. Statistical analysis also indicated that the level of Cosmc expression was negatively correlated with severe proteinuria (P<0.05) instead of gross haematuria (P>0.05). CONCLUSION: These data suggested that the aberrant IgA O-glycosylation in IgAN was resulted from a downregulation of beta1,3GT chaperone (Cosmc) expression in B lymphocyte, which is closely associated with clinical characteristics of the disease. This downregulation might be one of the fundamental pathogenic abnormalities in IgAN.

Adult↗
PubMed2005

Anesthetic effect of epidural anesthesia with cephalad or caudad catheterization for ankle surgery or hemorrhoidectomy.

BACKGROUND: The larger size of the first sacral nerve root has been reported to be an unfavorable factor leading to sacral sparing in epidural anesthesia. Previous studies have shown that an adequate analgesic effect of the epidural block was achieved with the catheter placement in the caudal direction. In this study, the anesthetic effect of epidural anesthesia with catheter placement of a cephalic or caudad direction was compared in ankle and hemorrhoid surgery. METHODS: Twenty-one ASA physical status I or II patients undergoing surgery for ankle fractures with epidural anesthesia were enrolled and randomized into two groups. The epidural catheter was placed either to a cephalad (AU group) or caudal (AD group) direction. Another 21 patients undergoing hemorrhoidectomy were also randomized into two groups to receive epidural anesthesia in a similar way (HU and HD groups). The onset for, duration of, and recovery time from epidural anesthesia and the incidence of analgesic request were recorded. RESULTS: No significant differences were demonstrated when age, height, weight or sex were compared between the four study groups. The onset time of the block and the incidence of intrasurgical analgesic request were lower in the caudal subgroup when the ankle surgery patients were compared. Otherwise, there were no significant differences in the duration of anesthesia and time to recovery or level of anesthesia. CONCLUSION: Injection of local anesthetic solution through a caudally oriented epidural catheter produces faster onset and superior quality of anesthesia in comparison with the injection through the cephaladly oriented catheter in ankle surgery, but not hemorrhoidectomy.

Adult↗
PubMed2004

Nonsteroidal anti-inflammatory drugs increase expression of inducible COX-2 isoform of cyclooxygenase in spinal cord of rats with adjuvant induced inflammation.

Several lines of evidence have accumulated that release of excitatory amino acids, nitric oxide and prostaglandin E2 (PGE2) play a critical role in the development of peripheral tactile and thermal hypersensitivity in chronic inflammatory pain models. Synthesis of PGE2 is controlled by cyclooxygenase (COX), either the COX-1 or COX-2 isoform. COX-2 plays a central role in the inflammatory reactions. The relationship between central sensitization of a complete Freund's adjuvant (CFA) induced inflammation and expressions of COX-2 were assessed in a rat model of CFA injection induced inflammation. Moreover, the time course of analgesia and spinal COX-2 expression following intrathecal (IT) injection with a nonspecific COX inhibitor (ketorolac) and COX-2 inhibitor (celecoxib) were determined using Western blot and immunohistochemistry. COX-2 protein was slightly increased in the lumbosacral spinal cord at 24 h following subcutaneous injection of CFA in the plantar surface of the left hindpaw (p > 0.05). COX-1 was not detected in normal and CFA injection rats. Surprisingly, IT ketorolac or celecoxib significantly increased spinal COX-2 levels at 1 h post-IT injection (p < 0.05) both in inflamed and non-inflamed rats. Then, spinal COX-2 levels declined at 3 and 6 h post-IT injection. These results provide strong in vivo evidence that COX-2 activity but not level may play a central role in the Freund's adjuvant-induced inflammation. However, spinal COX-2 level was upregulated following IT ketorolac and celecoxib injection. These data implies that suppression of PGE2 activity may induce the expression of spinal COX-2 in Freund's adjuvant-induced pain model. Our study concludes that IT administration of COX-2 inhibitor or nonspecific COX inhibitor is associated with significant short-term increase in spinal COX-2 expression.

Animals↗
PubMed2004

Seeing the gene therapy: application of gene gun technique to transfect and decolour pigmented rat skin with human agouti signalling protein cDNA.

We developed a gene gun method for the transfer of human agouti signalling protein (ASP) cDNA to alter rat skin colour in vivo. Human ASP cDNA was cloned into a modified cytomegalovirus plasmid and delivered to the skin of Long-Evans rats by gene gun bombardment. Skin pigmentation, body weight and blood sugar of ASP cDNA-transfected rats were recorded against the control group, which were injected with plasmids encoding for green fluorescent protein. The treated skin showed lighter skin colour after 3 days of ASP gene transfection. This depigmentation effect was most prominent on day 14 and the skin gradually returned to its original pigmentation by day 28. Successful transfection of ASP gene in skin and hair follicles, as well as downregulation of melanocortin-1 receptor (MC1R) and tyrosinase expression upon treatment, was confirmed using immunohistochemistry and Western blot analysis. Body weight and blood sugar in the treated rats did not show statistically significant differences as compared to control groups. These observations demonstrate that gene transfer using the gene gun method can induce high cutaneous ASP production and facilitate a switch from dark to fair colour without systemic pleiotropic effects. Such a colour switch may be that ASP is acting in a paracrine fashion. In addition, this study verifies that ASP exerts its functions by acting as an independent ligand that downregulates the melanocyte MC1R and tyrosinase protein in an in vivo system. Our result offers new, interesting insights about the effect of ASP on pigmentation, providing a novel approach to study the molecular mechanisms underlying skin melanogenesis.

Agouti Signaling Protein↗
PubMed2004

Cytotoxic effects of gingival retraction cords on human gingival fibroblasts in vitro.

The objective of this study was to determine the cytocompatibility of three different extracts of gingival retraction cords and to compare the cytotoxic effect of these materials on human gingival fibroblasts. Gingival retraction cords impregnated with aluminium sulphate (Gingi-Aid), dl-adrenaline HCl (Gingi-Pak) and non-drug-impregnated cord (Gingi-Plain) were eluted with culture medium for 10 min and 24 h. Cytotoxicity was judged using a tetrazolium bromide reduction assay. Our data demonstrated that gingival retraction cords applied alone almost completely inhibited cell viability (P < 0.05). In addition, the results also showed that the eluates from aluminium sulphate-impregnated cord, dl-adrenaline HCl-impregnated cord and non-drug-impregnated cord were cytotoxic to primary human gingival fibroblast cultures (P < 0.05). The cell viability of incubation of gingival fibroblasts containing 10-min eluates of aluminium sulphate, dl-adrenaline HCl and non-drug-impregnated cord was 61, 21 and 70%, respectively. The cell viability of incubation of gingival fibroblasts containing 24 h eluates of aluminium sulphate, dl-adrenaline HCl and non-drug-impregnated cord was 68, 58 and 72%, respectively. It was found that dl-adrenaline HCl-impregnated gingival retraction cord was the most toxic gingival retraction cord among the materials tested in all cultures (P < 0.05). The cytotoxicity decreased in an order of dl-adrenaline HCl-impregnated cord > aluminium sulphate-impregnated cord > non-drug-impregnated cord. The extent or degree of the cytotoxicity depended on the materials tested. Gingival retraction cords have significant potential for gingival toxicity. Careful management of gingiva retraction cords would lower the risk of potential gingival tissue damage during clinical application procedure and thus increase the success of prosthodontic procedures.

Alum Compounds↗
PubMed2004

Induction of vascular endothelial growth factor expression in human pulp fibroblasts stimulated with black-pigmented Bacteroides.

AIM: To investigate the effect of black-pigmented Bacteroides on the expression of vascular endothelial growth factor (VEGF) gene in human pulp fibroblasts. METHODOLOGY: The supernatants of Porphyromonas endodontalis, Porphyromonas gingivalis and Prevotella intermedia were used to evaluate VEGF gene expression in human pulp fibroblasts. The levels of mRNAs were measured by the quantitative reverse-transcriptase polymerase chain reaction analysis. RESULTS: Black-pigmented Bacteroides induced significantly high levels of VEGF mRNA gene expression in human pulp fibroblasts (P < 0.05). In addition, the expression of VEGF depended on the bacteria tested. CONCLUSIONS: Black-pigmented Bacteroides may be involved in developing pulpal disease through the stimulation of VEGF production that would lead to the expansion of the vascular network coincident to progression of the inflammation.

Cells, Cultured↗
PubMed2003

Intrathecal pertussis toxin induces thermal hyperalgesia: involvement of excitatory and inhibitory amino acids.

Intrathecal pertussis toxin injection has been used as a neuropathic pain model. In the present study, its effects on cerebrospinal fluid biochemistry and nociceptive behavioral expression were examined in rats. Cerebrospinal fluid dialysate samples were collected and pertussis toxin was injected using an intrathecally implanted dialysis loop catheter; samples were collected and hyperalgesia behavior was noted every 2 days for 8 days after pertussis toxin injection. Pertussis toxin injection induced thermal hyperalgesia which peaked between day 2 and 4; no cold allodynia was observed. Pertussis toxin at all doses tested (0.5, 1, or 2 microg) also induced a significant increase in cerebrospinal fluid concentrations of aspartate and glutamate between days 2 and 8, while level of the inhibitory amino acid glycine were significantly decreased by the two higher doses of pertussis toxin. Intrathecal administration of the N-methyl-D-aspartate receptor antagonist D-2-amino-5-phosponovaleric acid (10 microg) or glycine (200 microg), inhibited pertussis toxin-induced thermal hyperalgesia. Pertussis toxin injection had no effect on serine, glutamine, and taurine concentrations. These results show that intrathecal pertussis toxin injection induces thermal hyperalgesia and it is associated with an increasing of excitatory and a decreasing of inhibitory amino acids release in the spinal cord.

Animals↗
PubMed2003

Intractable livedoid vasculopathy successfully treated with hyperbaric oxygen.

We describe a new method for treating livedoid vasculopathy. The typical presentation of livedoid vasculopathy includes chronic, recurrent painful ulcers, satellite scar-like atrophy and telangiectasia involving the lower extremities. Histologically, these lesions show areas of ulceration and dermal vessel occlusion without frank inflammatory cell infiltration. There is currently no satisfactory therapy available for this disease. Hyperbaric oxygen (HBO) has recently established itself as one of the most effective methods of treating ischaemic wounds, including diabetic ulcers. We used this therapy in two patients whose lesions were resistant to multiple therapeutic modalities. Not only did their ulcers respond rapidly to the HBO therapy, but the disturbing wound pain also resolved at the same time. To our knowledge, this is the first successful trial of HBO therapy in livedoid vasculopathy. We believe this to be a very promising new therapy for livedoid vasculopathy and to be worth further investigation.

Adolescent↗
PubMed2003

Induction of interleukin-6 gene expression by pro-inflammatory cytokines and black-pigmented Bacteroides in human pulp cell cultures.

AIM: To investigate the effect of pro-inflammatory cytokines and black-pigmented Bacteroides on the expression of IL-6 gene in human pulp fibroblasts. METHODOLOGY: IL-1alpha, tumour necrosis factor-alpha (TNF-alpha) and the supernatants of Porphyromonas endodontalis, P. gingivalis and Prevotella intermedia were used to evaluate IL-6 gene expression in human pulp fibroblasts. The levels of mRNAs were measured by the quantitative reverse-transcriptase polymerase chain reaction analysis. RESULTS: Investigations of the time dependence of IL-6 mRNA expression in pro-inflammatory cytokines-treated cells revealed a rapid accumulation of the transcript after 2 h of exposure and remained elevated throughout the 24-h incubation period. In addition, black-pigmented Bacteroides also induced IL-6 gene expression in human pulp fibroblasts. CONCLUSIONS: Pro-inflammatory cytokines and black-pigmented Bacteroides may be involved in developing pulpal inflammation through the stimulation of IL-6 production.

Bacteroides↗
PubMed2003

Induction of interleukin-8 gene expression by black-pigmented Bacteroides in human pulp fibroblasts and osteoblasts.

AIM: To investigate the effect of black-pigmented Bacteroides on the expression of interleukin (IL)-8 gene in human pulp fibroblasts and osteoblasts. METHODOLOGY: The supernatants of Porphyromonas endodontalis, P. gingivalis and Prevotella intermedia were used to evaluate IL-8 gene expression in human pulp fibroblasts and osteoblasts. The levels of mRNAs were measured by the quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. RESULTS: Investigations of the time-dependence of IL-8 mRNA expression in black-pigmented Bacteroides-treated pulp fibroblasts and osteoblasts revealed a rapid accumulation of the transcript after 2 h of exposure, and remained elevated throughout the 24-h incubation period. In addition, IL-8 mRNA gene expression was also found in human osteoblasts stimulated with black-pigmented Bacteroides. However, black-pigmented Bacteroides was found to be more effective in the induction of IL-8 mRNA gene expression in osteoblasts than in pulp fibroblasts (P < 0.05). CONCLUSIONS: Black-pigmented Bacteroides are capable of amplifying the local immune response and promoting pulpal/periapical tissue inflammation by stimulating pulp fibroblasts and osteoblasts to express IL-8.

Analysis of Variance↗
PubMed2003

Gene therapy for bladder pain with gene gun particle encoding pro-opiomelanocortin cDNA.

PURPOSE: Interstitial cystitis is a bladder hypersensitivity disease associated with bladder pain that has been a major challenge to understand and treat. We hypothesized that targeted and localized expression of endogenous opioid peptide in the bladder could be useful for the treatment of bladder pain. Pro-opiomelanocortin (POMC) is one of such precursor molecules. In this study we developed a gene gun method for the transfer of POMC cDNA in vivo and investigated its therapeutic effect on acetic acid induced bladder hyperactivity in rats. MATERIALS AND METHODS: Human POMC cDNA was cloned into a modified pCMV plasmid and delivered into the bladder wall of adult female rats by direct injection or the gene gun. Three days after gene therapy continuous cystometrograms were performed using urethane anesthesia by filling the bladder (0.08 ml per minute) with saline, followed by 0.3% acetic acid. Bladder immunohistochemical testing was used to detect endorphin after POMC cDNA transfer. RESULTS: The intercontraction interval was decreased after intravesical instillation of acetic acid (73.1% or 68.1% decrease) in 2 control groups treated with saline or the gene gun without POMC cDNA, respectively. However, rats that received POMC cDNA via the gene gun showed a significantly decreased response (intercontraction interval 35% decreased) to acetic acid instillation, whereas this antinociceptive effect was not detected in the plasmid POMC cDNA direct injection group. This effect induced by POMC gene gun treatment was reversed by intramuscular naloxone (1 mg/kg), an opioid antagonist. Increased endorphin immunoreactivity with anti-endorphin antibodies was observed in the bladder of gene gun treated animals. CONCLUSIONS: The POMC gene can be transferred in the bladder using the gene gun and increased bladder expression of endorphin can suppress nociceptive responses induced by bladder irritation. Thus, POMC gene gun delivery may be useful for the treatment of interstitial cystitis and other types of visceral pain.

Animals↗
PubMed2002

Induction of connexin 37 expression in a rat model of neuropathic pain.

Activation of cutaneous C-fibers by capsaicin or sciatic nerve transection increases the number of astrocytic gap junctions as well as the levels of connexin 43 in the dorsal horn on the stimulated side. Changes in connexin 37 mRNA expression following nerve injury have not been previously documented. We examined the role of gap junction protein connexin 37 in neuropathic hypersensitivity following peripheral nerve injury. Study results showed ipsilaterally increased connexin 37 mRNA levels proximally and distally in rat sciatic nerves after injury and behavioral thermal hyperalgesia at 7 and 14 days. Proximal and distal connexin 37 mRNA levels returned to baseline by 21 days. Sciatic nerve connexin 37 mRNA increases were proportional to the extent of thermal hyperalgesia, but skin, muscle, and lumbar spinal cord connexin 37 mRNA showed no significant changes. Neuropathic pain relief correlated with downregulation of connexin 37 mRNA. Results indicate that upregulation of connexin 37 mRNA following sciatic nerve injury correlates with subsequent thermal hyperalgesia, which suggests that gap junctions (connexin 37) are responsible for the hyperexcitability following peripheral nerve injury.

Animals↗
PubMed2002

Gene-gun particle with pro-opiomelanocortin cDNA produces analgesia against formalin-induced pain in rats.

Endogenous opioid peptides play an essential role in the intrinsic modulation and control of inflammatory pain, and could be therapeutically useful. These opioid peptides are synthesized as parts of larger precursor molecules. One such precursor molecule is pro-opiomelanocortin (POMC). In this study, we developed a gene-gun method for the transfer of POMC cDNA in vivo, and investigated its therapeutic effect on inflammatory pain in a rat model of formalin-induced pain. Human POMC cDNA was cloned into a modified pCMV plasmid and delivered to the skin of rats by gene gun. Three days after gene-gun injection, 1% formalin was injected. Endorphin levels were measured in the serum and skin after the formalin test, and skin histology was used to detect endorphin after green fluorescent protein (GFP; control) or POMC cDNA transfer. There was no significant difference in the results of acute nociceptive tests between the experimental and control groups. There was also no difference in response between the groups to phase 1 of the formalin test. However, rats which received POMC cDNA via gene-gun injection showed a significantly reduced response in phase 2 of the formalin test. Endorphin immunoreactivity in the skin increased approximately three- to four-fold in experimental animals compared with GFP-treated controls at day 3 after injection. The phase 2 response in animals treated with formalin and naloxone did not differ significantly from the control, implying that the analgesic effects of POMC cDNA particle injection in phase 2 of the formalin test are reversed by naloxone. There are two major findings from this study. First, in vivo DNA delivery by gene gun to the skin is feasible. Second, the production of beta-endorphin is insufficient to block phasic pain, but is effective against sensitization of the afferent neurons during phase 2 of the formalin test.

Adrenocorticotropic Hormone↗