Impact of 1-year treatment with dupilumab on work productivity in Japanese patients with atopic dermatitis

Atopic dermatitis (AD) places a burden on work productivity. Recently, dupilumab was approved for AD, but its impact on work productivity in Japanese patients has not been reported. Furthermore, data on the effect of long-term treatment with dupilumab on work productivity are limited. We investigated the work productivity and activity in Japanese patients with moderate-to-severe AD, utilizing the Japanese version of the Work Productivity and Activity Impairment (WPAI-AD-Japan) questionnaire. Furthermore, we examined the impact of dupilumab on work productivity. Adult moderate-to-severe AD patients treated with dupilumab for more than 12 months from March 2020 to June 2022 who filled out the WPAI-AD-Japan questionnaire were included. Twenty-eight adult AD patients were analysed. Absenteeism was low (mean: 5.3%), but presenteeism, work productivity loss and activity impairment were high (36.8%, 39.7%, 48.9%, respectively). Significant positive correlations were observed between work productivity loss and visual analogue scale (VAS) score of pruritus and between activity impairment and dermatology life quality index (DLQI). Dupilumab treatment significantly reduced presenteeism, work productivity loss and activity impairment at both 6 and 12 months. The extent of their amelioration was numerically higher at 12 months than at 6 months. The reduction rates in presenteeism, work productivity loss and activity impairment were positively correlated with the reduction rates in DLQI and VAS score of pruritus at 12 months. Dupilumab improved work productivity in Japanese AD patients. Long-term remission of pruritus and improved quality of life are important for comprehensive improvement of work productivity.

Early tumor response assessment may avoid serious immune-related adverse events in nivolumab and ipilimumab combination therapy for stage IV melanoma

Nivolumab and ipilimumab combination therapy is one of the most promising treatments for patients with melanoma. However, this combination therapy is highly toxic and causes serious adverse events (SAEs) in more than half of the patients.

Neutrophil-to-lymphocyte ratio is associated with survival and sentinel lymph node positivity in invasive cutaneous squamous cell carcinoma: A retrospective study

BACKGROUND

The neutrophil-to-lymphocyte ratio (NLR) is a known prognostic biomarker for survival and is predictive of sentinel lymph node (SLN) positivity in some cancers. However, its usefulness as a prognostic biomarker for cutaneous squamous cell carcinoma (cSCC) has not been fully investigated.

OBJECTIVE

Our objective was to investigate the relationship between the NLR and the disease-specific survival and SLN positivity in patients with cSCC.

METHODS

In this single-center retrospective case series, we analyzed patients with cSCC who underwent blood tests prior to the initiation of treatment at our oncology hospital. The relationship between the patients' clinical characteristics (including the NLR) and the disease-specific survival and SLN positivity was evaluated using univariate and multivariate analyses.

RESULTS

An elevated NLR was an independent prognostic factor for poor disease-specific survival and a predictive factor for SLN positivity.

LIMITATIONS

Limitations include the small number of participants and selection bias due to the large proportion of high-risk cases in our patient population.

CONCLUSION

NLR is a useful biomarker in cSCC because it is simple to measure and can predict prognosis.

Continued Chemotherapy After Concurrent Chemoradiotherapy Improves Treatment Outcomes for Unresectable Cutaneous Squamous Cell Carcinoma: An Analysis of 13 Cases

Background: There is no standard systemic therapy for unresectable cutaneous squamous cell carcinoma (ucSCC), although various chemotherapy regimens have been reported. In our department, concurrent chemoradiotherapy (CCRT) for ucSCC resulted in a 1-year survival rate similar to that of resectable cutaneous squamous cell carcinoma (cSCC). Treatment involves continued chemotherapy after CCRT. Here, we report the importance of continued chemotherapy after CCRT, based on treatment outcomes. Patients and Methods: We retrospectively evaluated 13 patients with ucSCC, assessing the overall survival, overall response rate (ORR), and disease control rate (DCR). Results: CCRT with continued chemotherapy resulted in an ORR of 84.6%, DCR of 92.3%, and 1-year survival rate of 75%. Of the 13 patients treated with CCRT with continued chemotherapy, 6 had no metastasis. The remaining 7 patients developed metastasis to other organs or lymph nodes beyond the regional lymph nodes, although most sites of metastasis were outside the irradiation area. Conclusion: We conclude that CCRT with continued chemotherapy was effective in treating the irradiation site (primary lesion and regional lymph nodes) and any organ metastasis, although, it is unclear for how long the treatment remains effective.

Dynamics of neutrophil and C-reactive protein reflect the clinical course of pyrexia during combination therapy with dabrafenib and trametinib

Pyrexia is the most common adverse event in patients with melanoma or other solid organ malignancies that are treated with the combination of dabrafenib and trametinib (combi-DT). Given the expanded indication for combi-DT, management of pyrexia is a high priority. No previous case series has revealed which blood markers reflect the course of pyrexia and there is no consensus on the management strategy for pyrexia. The current case series study describes the utility of neutrophil count (NC), neutrophil ratio (NR) and C-reactive protein (CRP) in 11 patients with metastatic melanoma and BRAF V600 mutations who experienced pyrexia during combi-DT in our department. We also described the clinical course of pyrexia episodes that were managed with the concomitant use of oral prednisolone and immediate withdrawal of combi-DT. Consequently, the analysis of 37 pyrexia episodes in 11 patients showed that the differences in NC, NR and CRP at the onset of pyrexia were significantly different from those at pyretolysis (P = 0.01, 0.006 and 0.03, respectively). Additionally, in the 24 pyrexia episodes treated with the concomitant use of oral prednisolone and the immediate withdrawal of combi-DT, the mean duration of pyrexia and the mean time to restart combi-DT were 3 and 6 days, respectively. Therefore, the blood markers that reflect the course of pyrexia during combi-DT may be helpful for the appropriate management of pyrexia; also, our management strategy for pyrexia successfully reduced the duration of pyrexia and did not require a long-term drug holiday. Further large-scale studies are required to verify our results.

Pharmacodynamic study of procaterol hydrochloride dry powder inhaler: evaluation of pharmacodynamic equivalence between procaterol hydrochloride dry powder inhaler and procaterol hydrochloride metered-dose inhaler in asthma patients in a randomized, double-dummy, double-blind crossover manner

Therapeutic equivalence between procaterol hydrochloride dry powder inhaler (Meptin DPI) and procaterol hydrochloride metered-dose inhaler (Meptin MDI), the currently marketed formulation, was assessed in 16 patients with bronchial asthma. The study was conducted in a randomized, double-dummy, double-blind crossover manner, using forced expiratory volume in the first second (FEV1) as an index of bronchodilatory effect. In Period I, the patients received 20 mcg of either Meptin DPI or Meptin MDI, and then crossed over in Period II after a washout interval of 3--28 days. Pharmacodynamic equivalence was accessed using AUC (FEV1)/h and peak FEV1 as indices, and the data were analyzed by analysis of variance (ANOVA). Factors used for the analysis were the treatment group and/or carryover effect, patients within each group, period, and treatment. The 90% confidence intervals for the differences between the two treatments were --0.0995 to --0.0204 (L) for mean AUC (FEV1)/h and --0.102 to --0.022 (L) for mean peak FEV1, both within the acceptance criteria of --0.15 to 0.15 (L). Meptin DPI was therefore assessed as being equivalent to the current Meptin MDI.

Hepatic abscess as a complication of the sump syndrome

We report a case of hepatic abscess associated with the sump syndrome. The patient was a 66-year-old woman who had undergone cholecystectomy and side-to-side choledochoduodenostomy for a common bile duct (CBD) stone in 1983, and who presented with fever and right lower chest pain. A hepatic abscess was diagnosed; after it was drained, percutaneous transhepatic biliary drainage was performed. Bacteriological studies revealed the presence of Bacteroides fragilis and Streptococcus intermedius in the pus in the hepatic abscess cavity, and Klebsiella pneumoniae and Pseudomonas aeruginosa in the bile. The hepatic abscess and cholangitis rapidly resolved in response to two drainage procedures. At surgery, simple closure of the anastomosis was performed, because free drainage was observed from the distal CBD into the duodenum, despite the existence of a periampullary diverticulum.

[The effect of anti-NGF and NGF on the responses to noxious heat in mice treated with capsaicin in the neonatal period]

Unexpectedly, despite the profound loss of C-fibers in the dorsal roots of mice injected capsaicin on day 2 of life, they showed normal responses to nociceptive heat. To examine the cause of this conflicting phenomenon, we studied the effect of anti-NGF and NGF on the response to noxious heat in mice pretreated with capsaicin. Capsaicin (50 mg/kg) was injected on the 2nd day of life, and 5 days later, anti-NGF (3 microliters/g) was daily injected for 30 days. Capsaicin was also injected on day 10 of life, and NGF (3 microliters/g) was daily injected for 30 days from 5 days after treatment. From 10 days after capsaicin treatment, the mice were stimulated by radiant heat (Hargreaves' method) every 10 days up to 60 days and every 20 days from 60 to 80 days. The same test was undertaken in age-matched mice. Withdrawal latencies of the mice treated with both capsaicin and anti-NGF were significantly retarded compared with those of the animals treated with only capsaicin. Thus, it was suggested that the treatment of capsaicin on day 2 induces sprouting from the remaining primary sensory neurons. On the other hand, the latencies of the mice treated with both capsaicin and NGF were short compared with those of the animals treated with only capsaicin. The results may be attributed to the reinforcement of the sprouting from remaining neurons. However, we must not neglect the effect of individual treatment with NGF or anti-NGF.

Neuroanatomical effects of capsaicin on the primary afferent neurons

Studies by N. JANCSO and his associates in the 1970's established that capsaicin in paprika exerts selective damage on nociceptive primary sensory neurons. The physiological and pharmacological aspects of capsaicin's effect have been repeatedly reviewed, but no report seems available concerning the neuroanatomical changes caused by capsaicin. This paper first reviews the neuroanatomical aspect of the lesion caused by capsaicin. Special attention is paid to quantitative estimations made by our group and others on the loss of dorsal root ganglion (DRG) cells, dorsal root nerve fibers, the saphenous nerve, chorda tympani nerve, and pulp nerves after neonatal treatment with capsaicin. The degenerating process of DRG cells induced by capsaicin is discussed with respect to necrosis and apoptosis. The capsaicin receptors found recently are concisely introduced with reference to their action. A discrepancy between a marked loss of dorsal root C-fibers and an unexpectedly intact response to noxious heat in mice treated with capsaicin at neonate is discussed, and attension is given to nerves sprouting from capsaicin-resistant DRG cells in the superficial dorsal horn. In addition, the architecture of the synapses between the central endings of the capsaicin-sensitive primary afferent neurons and the intrinsic inhibitory interneurons is described and its possible significance considered in terms of the transmission of nociceptive information.

Age-related changes in the response to thermal noxious heat and reduction of C-fibers by neonatal treatment with capsaicin

Developmental changes of the response to nociceptive heat were examined in mice treated with capsaicin (50 mg/kg) on postnatal days 2-15. Tests of hot-plate (55 degrees C) and irradiation by infrared (IR test) were carried out after 10 days of capsaicin administration up to 120 days at intervals of 10 or 20 days. The time until forepaw (hot-plate) and hindpaw (IR test) withdrawal was assessed as the response latencies to suprathreshold and thermal threshold, respectively. Moreover, the numbers of unmyelinated C-fibers and myelinated fibers in the L4 dorsal roots of the animals treated on postnatal days 2 and 5 were counted on electron micrograph montages. Despite the marked reduction of C-fibers (60% mean decrease) in the 4 dorsal roots of the animals treated on postnatal day 2, thresholds were normal compared with those of controls. However, the animals treated with capsaicin on postnatal day 5 showed an apparent delay of thermal threshold latency only in the IR test, although the mean reduction of C-fibers was very likely the same as that of the animals pretreated on day 2. The reduction of C-fibers in mice treated on postnatal days 10 and 15 was lower than the animals treated on days 2 or 5, but their threshold latencies were significantly increased (hypoalgesia). A possible implication of these findings is discussed on the basis of the development of inhibitory systems in the intraspinal and supraspinal dorsal horn and sprouting from the surviving primary afferent neurons in the superficial dorsal horn.

FRAP-positive and capsaicin-sensitive terminals in the substantia gelatinosa of the mouse spinal trigeminal nucleus caudalis

FRAP (fluoride-resistant acid phosphatase)-reactivity in the substantia gelatinosa of the mouse spinal trigeminal nucleus caudalis (STNC) was examined by light and electron microscopy. Degenerated figures of terminals caused by capsaicin were compared with the FRAP-positive terminals. Scalloped (fan-like) or indented, sinuous, slender, and cap-like figures with closely packed agranular synaptic vesicles of various sizes were common to both FRAP-positive and capsaicin-sensitive terminals. These terminals had glomerular or nonglomerular endings. Sometimes FRAP-positive and capsaicin-sensitive glomerular terminals made presynapses with surrounding dendrites. Frequently, both nonglomerular terminals were in direct contact with the neuronal soma. The terminal features of FRAP-positive and capsaicin-sensitive ones in the mouse STNC are the same as those seen in the superficial dorsal horn of the spinal cord. These findings suggest that some of the FRAP-positive terminals are capsaicin-sensitive, thereby indicating their nociceptive primary afferent.

Insulinoma with hyperproinsulinemia during hypoglycemia and loss of expression of vacuolar-type H(+)-ATPase (V-ATPase) in the tumor tissue

Hypoglycemia with a low serum immunoreactive insulin (IRI) level and serum immunoreactive C-peptide (IRC) level was found in a 74-yr-old female. Although a fasting test induced hypoglycemia, the responses of IRI and IRC during the fasting test, and the results of a glucose tolerance test, glucagon test, and secretin test did not indicate the presence of an insulinoma. However, the serum proinsulin level before the fasting test was 130.5 pmol/L (N: 3.0-10.0 pmol/L), and this high level was maintained throughout the test. Soon after surgical enucleation of the tumor, the patient's blood glucose levels increased. Postoperatively, the hypoglycemic status resolved, and the serum proinsulin levels returned to normal (2.8 pmol/L). Histopathological studies revealed a typical insulinoma. Immunohistochemical studies by the recently developed method for vacuolar-type H+ (V-ATPase), which is responsible for acidification of the intracellular compartments in eukaryotic cells, showed that normal islets stained positive, but not the tumor. This finding indicates that the insulin-secretory granules in the insulinoma cells existed in a microenvironment in which V-ATPase activity had been lost. This suggests that the reduced activity of V-ATPase on the endomembrane of the insulin-secretory granules in insulinomas may result in loss of the acidic microenvironment and impaired conversion of proinsulin by converting enzymes.

A new model for pancreatitis

Pancreatitis induced by ligation of the pancreatic duct produces morphologic similarities to human pancreatitis. This model is easily performed in big animals, but it is very difficult to perform pancreatic duct ligation in small animals. Many experimental studies of pharmaceutical treatments for pancreatitis used pancreatic duct-ligation models, but it is also difficult to evaluate the efficacy of the drugs used, because the animals used are of different species with individual differences. To overcome these problems, we ligated the main pancreatic duct of the splenic lobe by a 5.0 absorbable suture by using a surgical microscope and left the gastroduodenal lobe intact in the same rats. This model produced damaged pancreatic tissue in one part and normal pancreatic tissue in another part of the pancreas in the same animals, biochemically and histologically. We evaluated the effect of a new protease inhibitor (ONO-3404) on this preliminary model and found this new protease inhibitor demonstrated a hypertrophic effect on the damaged pancreatic tissue and the normal pancreatic tissue in the same animals. This model is also useful to study pharmaceutic treatment for pancreatic insufficiency and to study chemically induced pancreatic carcinogenesis in the damaged pancreatic tissue and the normal pancreatic tissue in the same animals.

Relationship of substance P- and CGRP-immunoreactive central endings of the primary afferent neurons to GABAergic interneurons in the guinea pig substantia gelatinosa

The synaptic relationships between primary afferent central endings containing substance P (SP) and calcitonin gene-related peptide (CGRP) and GABAergic interneurons in the guinea pig substantia gelatinosa of the lumbar spinal dorsal horn were studied. The pre-embedding PAP method was used for detection of GABA and the post-embedding double immunogold labeling method for SP and CGRP detection. Immunogold particles specific for SP and CGRP were mainly localized separately or together in large synaptic vesicles devoid of dense cores. SP and CGRP immunoreactivity was separate or co-localized in small roundish, slender, sinuous or large scalloped (fan-like) terminals with closely packed round agranular synaptic vesicles of various sizes and few large dense core vesicles and mitochondria, which are thought to be capsaicin-sensitive primary afferent terminals. These SP- and CGRP-immunoreactive boutons make presynaptic or symmetric contacts with GABAergic dendrites and soma. These findings suggest that the central endings of nociceptive primary afferents transmit pain stimuli to intrinsic inhibitory interneurons, thereby modulating nociceptive information via a postsynaptic circuit.

Left acute scrotum associated with appendicitis

A 10-year-old boy, who had a mild inguinal hernia in his left scrotum, was referred to our clinic because of redness of the scrotal skin and tenderness of the left scrotal contents. Scrotal echography showed a hypoechoic lesion around the normal testis and epididymis. Because torsion of either the testis or testicular appendage was suspected, the scrotum was opened and 1.5 mL of purulent fluid was observed in the tunica vaginalis with inflammatory tissue around the testis and epididymis. On the first postoperative day, a low grade fever and abdominal tenderness persisted, however, the abdomen was flat and soft. There was no marked tenderness over McBurney's point, but there was moderate tenderness over Lanz's point on deep palpation. Abdominal sonography and magnetic resonance imaging revealed abscess formation between the bladder and the sacrum. With a diagnosis of perforation of the appendix, a laparotomy was performed. The inguinal hernia sac could not be observed on inspection, and it was not possible to palpate the left side because of severe adhesion due to infection. Also, the neck of the right inguinal sac could not be seen. The appendix specimen was gangrenous. On the second postsurgical day, all symptoms and signs disappeared. We present this rare condition and discuss the difficulty in establishing a diagnosis.

Inhibitory effect of green tea extract on the process of pancreatic carcinogenesis induced by N-nitrosobis-(2-oxypropyl)amine (BOP) and on tumor promotion after transplantation of N-nitrosobis-(2-hydroxypropyl)amine (BHP)-induced pancreatic cancer in Syrian hamsters

Epidemiologic studies have shown a lower risk of gastrointestinal cancer in green tea drinkers. In the present study, the inhibitory effect of green tea extract (GTE) on the process of pancreatic carcinogenesis induced by N-nitrosobis-(2-oxypropyl)amine (BOP) and on tumor promotion after transplantation of N-nitrosobis-(2-hydroxypropyl)amine (BHP)-induced pancreatic cancer were investigated in hamsters. In the first experiment, shortly after the initiation of pancreatic carcinogenesis by BOP, the animals in the GTE group were given GTE (0.5 mg/L) in their drinking water and the control group was given tap water. All animals were sacrificed 24 weeks later. There were no significant differences in body weight, water intake, or food consumption between the two groups during the experiments. GTE consumption was approximately 1.25 mg/day/100 g body weight during this experiment. Seven of the 13 hamsters (54%) in the control group were found to have pancreatic tumors, versus six of the 18 hamsters (33%) in the GTE group. The average number of tumors in the control group was 1.0/hamster, compared with 0.5/hamster in the GTE group. The overall incidence of macroscopic pancreatic tumors in the GTE group was about half that in the control group. The incidence of pancreatic cancer was 54% (12/13) in the control group and 44% (8/18) in the GTE group. The number of pancreatic cancers, including invasive carcinoma and carcinoma in situ, in the GTE group was 0.88/hamster, significantly lower than in the control group (1.68/hamster) (p < 0.05). The incidence of atypical ductal hyperplasia, which is thought to be an early pancreatic cancer, was also significantly lower in the GTE group than in the control group (1.50/hamster vs. 4.65/hamster) (p < 0.05). In the second experiment, 1-mm3 pieces of BHP-induced pancreatic cancer were transplanted into the back of hamsters. The control group (N = 16) was maintained on the basal diet and tap water throughout the experiment, and the GTE group (N = 16) was also maintained on the basal diet and tap water for the first 3 weeks after transplantation, when successful transplantation was confirmed and, thereafter, given tap water containing GTE (0.5 mg/L) for an additional 12 weeks. Tumor growth was similar in both groups until 11 weeks after transplantation, but inhibition of tumor growth became apparent after 11 weeks in the GTE group. At 13 weeks, the average tumor volume in the GTE group was 1.01 +/- 0.11 x 104 mm3, significantly smaller than that in the control group (1.98 +/- 0.37 x 104 mm3) (p < 0.05). The results demonstrated that GTE has an inhibitory effect on the process of pancreatic carcinogenesis and on tumor promotion of transplanted pancreatic cancer. These results suggest that GTE may come to serve as a chemopreventive and chemotherapeutic agent for pancreatic cancer.

Fluoride-resistant acid phosphatase (FRAP)-positive afferent terminals make synaptic contact with interneuronal soma in the substantia gelatinosa of the mouse spinal dorsal horn

Fluoride-resistant acid phosphatase (FRAP)-reactive terminals making contact with interneuronal soma are found in the substantia gelatinosa of the mouse spinal dorsal horn. About one half of the interneuronal somata receive FRAP-positive boutons. By electron microscopy, these FRAP-positive terminals appear small, dark, slender, roundish, cap-like, ellipsoid or sinuous and electron-dense, scalloped (fan-like) contours with clear spherical synaptic vesicles of variable size, some large dense-core vesicles and mitochondria. All these features are very similar to those of capsaicin-sensitive terminals. Thus they are considered to be nociceptive primary afferent endings. Therefore, some of the FRAP-positive terminals are suggested to have a modulatory role in the nociceptive circuit in the substantia gelatinosa.

Taste-modifying triterpene glycosides from Staurogyne merguensis

Five new oleanane-type triterpene glycosides named strogins 1-5 were isolated from leaves of Staurogyne merguensis. Their structures were determined on the basis of chemical and spectral evidence. After strogins 1, 2 and 4 were held in mouth, water elicited a sweet taste. On the other hand, strogins 3 and 5 had no activity. The structure-activity relationship is discussed.

Inhibitory effect of sarcophytol A on pancreatic carcinogenesis after initiation by N-nitrosobis(2-oxypropyl)amine in Syrian hamsters

Sarcophytol A (SaA), a cembrane-type diterpene, inhibits pancreatic carcinogenesis induced by N-nitrosobis(2-oxypropyl)amine (BOP) in hamsters. The experimental groups received two injections of BOP at 70 mg/kg dose, followed 2 weeks later by a 20 mg/kg dose injection, and were fed a basal diet or 0.01 and 0.05% SaA diets starting 1 week after the second injection of BOP. Control groups were injected with normal saline and fed the basal diet or the 0.05% SaA diet. All animals were killed 30 weeks after the start of the experiments. Seventeen BOP-treated hamsters fed the basal diet developed pancreatic tumors (77.3%) while only 12 of 21 hamsters fed the 0.01% SaA diet (57.1%) and 12 of 23 hamsters fed the 0.05% SaA diet (52.2%) developed pancreatic tumors. Pancreatic lesions included ductal hyperplasia, atypical ductal hyperplasia, and carcinoma in situ. Microscopic invasive carcinoma induced by BOP and the incidence of larger pancreatic tumors in hamsters were significantly higher in hamsters fed the basal diet than in hamsters fed the SaA diet (p < 0.05). The proliferating cell nuclear antigen (PCNA) labeling index of pancreatic carcinoma in BOP-treated hamsters fed the basal diet was 41.2 +/- 13.4%, whereas BOP-treated hamsters fed 0.01 and 0.05% SaA diets yielded PCNA indexes of 26.8 +/- 8.3 and 28.4 +/- 7.0%, respectively. k-ras mutation was detected in 40% of cancers in both groups. No pancreatic tumors developed in saline-treated groups, and no differences in body weights or histological findings in their organs, including the pancreas, were observed in either group. These findings suggest that SaA not only inhibits BOP-induced pancreatic carcinogenesis in hamsters, but also provides antipromotion and antiprogression effects on these tumors, even when SaA commences 1 week after the initiation of pancreatic carcinogenesis.

Role of endogenous and exogenous cholecystokinin in experimental acute pancreatitis induced in rats by the duodenal loop technique

The role of endogenous cholecystokinin (CCK) release and exogenous CCK-8 administration in the development and progression of acute pancreatitis and in the early recovery phase of acute pancreatitis were investigated in rats with closed duodenal loop (CDL)-induced pancreatitis. The subcutaneous injection of CCK-8 (2 micrograms/kg) stimulated a physiological level of pancreatic enzyme secretion in normal control rats, but did not lead to any biochemical or histological evidence of acute pancreatitis. A higher dose of CCK-8 (8 micrograms/kg), however, did produce both biochemical and histological evidence of acute pancreatitis in the normal control rats. When 2 micrograms/kg of CCK-8 was injected subcutaneously in rats 6 and 12 h after the creation of the CDL, neither the biochemical nor the histological findings of acute pancreatitis showed any progression compared with the changes in controls given no CCK-8. Serum CCK levels, measured by radio-immunoassay, increased significantly from mean levels of 5.39 pg/ml (+/- 0.95 SD) before creation of the CDL to 42.06 pg/ml (+/- 2.27 SD) 6 h after, and 41.95 pg/ml (+/- 1.88 SD) 12 h after its creation (P < 0.01). The difference between serum CCK levels at 6 and 12 h was not statistically significant. Following the release of the loop, serum CCK levels decreased gradually, especially in rats in which the loop was released 6 h after being created. Although no marked biochemical and histological changes of acute pancreatitis were observed following the administration of 2 micrograms/kg of CCK-8 to rats upon release of the loop 6 h and 12 h after its creation, a higher dose of CCK-8 (8 micrograms/kg) in these rats adversely affected both the biochemical and histological findings of acute pancreatitis. Based on these findings, it was concluded that neither endogenous CCK release, as a result of the CDL, nor physiological stimulation of the pancreas by exogenous CCK-8 administration, caused progression from edematous to hemorrhagic acute pancreatitis, and neither CCK treatment had any adverse effect on the early recovery phase of CDL-induced acute pancreatitis. A pharmacological dose of CCK, however, exacerbated the acute pancreatitis, even in the early recovery stage.

Effects of a new synthetic lipid A on endogenous tumor necrosis factor production and antitumor activity against human pancreatic cancer cells

The effects of a synthetic lipid A on tumor necrosis factor (TNF) production and antitumor activity against human pancreatic cancer cells were investigated. Lipid A (10 mg/kg) was injected into normal rats and mice and serum TNF levels were measured. Lipid A-induced inhibition of Molt 4 and MIA paca-2 cells in culture were measured by counting viable cells. Activity of lipid A against transplanted human pancreatic cancer cells (MIA paca-2, Panc-1) was examined by determining tumor volume, necrosis, and survival rate after intraperitoneal injections of lipid A (10 and 20 mg/kg) over 4 weeks. Serum TNF levels increased 80-fold in rats and 100-fold in mice after intravenous lipid A injection. Although specific tumor growth inhibition by lipid A was not observed in vitro, tumor growth was significantly inhibited, and the survival rate was improved in pancreatic cancer cell-transplanted nude mice treated with lipid A compared with controls. Synthetic lipid A induces TNF production and has antitumor activity against transplanted pancreatic cancer cells. Further studies of this lipid A as an agent for pancreatic cancer are warranted.

Evidence of synaptic contacts of nociceptive primary afferent central terminals on GABAergic interneurons in the substantia gelatinosa

Recently, we showed that capsaicin induced the degeneration of not only glomerular CI terminals but also of non-glomerular CI terminals making presynaptic contact with interneuronal soma. Studies of the nature of interneurons making contact by nonglomerular CI terminals should provide important information to facilitate our understanding of the processing of nociceptive impulses in the substantia gelatinosa. The most likely candidate molecule involved in this process in these interneurons is gamma-aminobutylic acid (GABA). Therefore, ultrastructural relationships between nonglomerular CI terminals land GABAergic interneuronal soma in the mouse substatia gelatinosa were examined by an immunocytochemical method using an antibody to GABA. Terminals with the same profiles as the CI terminals, i.e., slender, sinuous and scalloped terminals filled with clear synaptic vesicles, were found to make synaptic contacts with GABA-immunoreactive somata. Thus, nociceptive primary afferents are suggested to modulate pain transmission by themselves via GABAergic neurons in the substantia gelatinosa.

Effects of bradykinin receptor antagonist on the release of beta-endorphin and bradykinin and on hemodynamic changes in a canine model of experimental acute pancreatitis

Bradykinin and beta-endorphin increases during acute pancreatitis are thought to contribute to the development of hypotension and myocardial depression in acute pancreatitis. beta-Endorphin release is mediated by trypsin-like enzymes and bradykinin from the pituitary gland. This study was undertaken to investigate the effect of a long-acting bradykinin receptor antagonist on bradykinin and beta-endorphin release and on hemodynamic changes during acute pancreatitis. Pancreatitis was induced by the injection of autologous bile mixed with trypsin into the main pancreatic duct after ligation of the accessory duct. Serum bradykinin and plasma beta-endorphin levels and cardiovascular function were measured. Twelve dogs (control group) were given 10 ml/kg/h of lactate Ringer's solution intravenously beginning 1 h before the induction of pancreatitis and continuing throughout the experiments. Six dogs received an intravenous infusion of 0.6 mg/kg/h of a new bradykinin receptor antagonist, HOE 140, D-Arg-[Hyp3, Thi5, D-Tic, Oic8]-bradykinin, in lactate Ringer's solution soon after the induction of pancreatitis. Six of twelve dogs in the control group, and none of the six dogs in the bradykinin receptor antagonist group, died during the experiments. Serum bradykinin levels in both groups increased until 1 h after the induction of pancreatitis, but thereafter the levels in the bradykinin receptor antagonist group decreased gradually until 5 h after induction, and levels were significantly lower than those in the control group (p < 0.05). Plasma beta-endorphin levels in the control group increased significantly, to 291.8 pg/ml (+/- 6.6 SEM) 5 h after the induction of pancreatitis, from the mean levels of 47.8 pg/ml before the induction of pancreatitis, while the mean beta-endorphin level in the bradykinin receptor antagonist group did not increase after the induction of pancreatitis. Infusion of the bradykinin receptor antagonist improved survival rates, hypotension, myocardial depression, and plasma lactate, suggesting that the bradykinin receptor antagonist inhibited the release of bradykinin and beta-endorphin, which contributed to the clinical improvement.

Central terminals of capsaicin-sensitive primary afferent make synaptic contacts with neuronal soma in the mouse substantia gelatinosa

Degeneration of primary afferent central terminals (C-terminals) that contact neuronal soma in the substantia gelatinosa of the spinal dorsal horn was examined by electron microscopy 2 h after s.c. injection of capsaicin into newborn and adult mice. The C-terminals were small, dark, sinuous or slender terminals with clear synaptic vesicles in the early postnatal period. They are thought to develop into scalloped CI-terminals, surrounded by dendrites and a few axonal endings, forming synaptic glomeruli. The same type of nonglomerular terminals making presynaptic contacts with neuronal soma showed degeneration in both the newborn and adult animals, and were identified as capsaicin-sensitive CI-terminals. This finding suggests that capsaicin-sensitive C-fibers have a modulatory role on their own nociceptive input besides functioning in nociceptive transmission in the substantia gelatinosa.

Early morphological changes of primary afferent neurons and their processes in newborn mice after treatment with capsaicin

Degenerating figures of dorsal root ganglion (DRG) neurons and their central and peripheral processes (dorsal root and saphenous nerve) and terminals (central terminals in the superficial dorsal horn and cutaneous nerve of the hind paw dorsal skin) of neonatal mice were examined 30 min, 1, 2 and 5 h, and 2, 3, 5, and 10 days after subcutaneous injection of capsaicin on post-natal day 2. Many small DRG neurons showed degeneration 1 h after treatment. Scarcely any features of degeneration were seen in the DRG and dorsal root 10 days after treatment. The degenerating aspects of terminal axons in the marginal layer of the superficial dorsal horn were characterized by enlarged round axons with closely packed osmiophilic materials, lamellar bodies, and loss of axoplasmic organelles. Two types of central terminals (C-terminals) showed degeneration in the substantia gelatinosa from 30 min after treatment onward. One type consisted of small, round, sinuous or slender dark terminals (CI-terminals), and the other of large, pale, round or angular terminals (CII-terminals). Those that degenerated markedly had homogeneously electron-dense axoplasm with dilated synaptic vesicles and inclusion bodies. Extensive degeneration of terminal axons in the marginal layer occurred 5 h after treatment, whereas conspicuous degeneration of C-terminals occurred from 30 min to 10 days after treatment in the substantia gelatinosa. CI-terminals showed marked degeneration during the first 3 days, whereas marked degeneration of CII-terminals occurred between 5 and 10 days after treatment. This time difference between the peaks of degeneration of CI- and CII-terminals indicates an important difference in the origins of these two types of capsaicin-sensitive, nociceptive fibers in the superficial dorsal horn; CI-terminals are derived from small DRG cells, whereas CII-terminals are derived from larger DRG cells. Unmyelinated axons in the dorsal root, saphenous nerve, and dorsal skin of the hind paw showed similar degeneration patterns 2 h after treatment to those of terminal axons in the marginal layer. Thus, the degenerating profiles in the marginal layer suggest that these axons arose from collaterals of unmyelinated primary axons descending or ascending within the marginal layer. Numerous enlarged degenerating axons showing vacuolation were conspicuous in the dorsal skin 3 days after treatment. The synchronous degeneration of the smaller DRG neurons, their central and peripheral processes, and their CI-terminals in the substantia gelatinosa supports the idea that the smaller DRG neurons are directly influenced by capsaicin, and that their degeneration is followed by centrifugal degeneration.

Sarcophytol A: a new chemotherapeutic and chemopreventive agent for pancreatic cancer

Sarcophytol A (SaA), a cembrane-type diterpene isolated from the marine soft coral Sarcophyton glaucum showed anticancer and cancer preventive effects in two different experiments. Growth of transplanted human pancreatic cancer cells (MIA paca-2, 1 x 10(7)) in nude mice (BALB/C 4W female) (Experiment 1) and pancreatic carcinogenesis induced by N-nitrobis-(2-hydroxypropyl) amine (BHP, 500 mg/kg) in Syrian golden hamsters (7W female) (Experiment 2) were inhibited by feeding the animals a diet containing 0.01% SaA. In Experiment 1, on day 29 after transplantation, tumor volume was significantly less in the SaA group than in the control group (1,759 + 310 mm3 vs. 2,364 + 467 mm3) (p < 0.05). In Experiment 2, the incidence of pancreatic tumors in the SaA group was 42.8% and that in the control group was 90.0% at 25-27 weeks. Thus, pancreatic carcinoma developed more slowly in the SaA group than in the control group. In addition, the incidence of atypical ductal hyperplasia and carcinoma in situ was lower in the SaA group. These results indicate that oral SaA administration is an effective vehicle for inhibition of certain types of cancer in hamsters.

Effect of a new cholecystokinin receptor antagonist (KSG 504) on the early stage of the healing process in acute pancreatitis induced in rats by the closed duodenal loop technique

Creation of a closed duodenal loop produced edematous acute pancreatitis within 6 h and hemorrhagic acute pancreatitis within 12 h in male Sprague-Dawley rats. The pancreatitis thus established tended to improve after releasing the loop. We investigated the effect of a new cholecystokinin receptor antagonist, KSG 504, on the healing process in edematous and hemorrhagic acute pancreatitis after releasing the loop. Serum amylase and lipase levels in the control group decreased gradually after releasing the loop, but the reductions were not significant. In both the group treated with KSG 504 intravenously and the group treated subcutaneously, serum amylase and lipase levels decreased markedly upon release of the loop in edematous acute pancreatitis. Furthermore, the histologic changes in edematous acute pancreatitis improved more rapidly than in the control group. However, no such biochemical or histologic evidence of improvement was observed in hemorrhagic acute pancreatitis. The new cholecystokinin receptor antagonist, KSG 504, displayed a therapeutic effect in edematous acute pancreatitis but not in hemorrhagic acute pancreatitis. These findings suggest that endogenous cholecystokinin release induced by the closed duodenal loop may have a contributory role in the development of edematous acute pancreatitis but not of hemorrhagic acute pancreatitis.

The therapeutic effect of a new synthetic protease inhibitor (E-3123) on hemodynamic changes during experimental acute pancreatitis in dogs

The therapeutic effect of a new synthetic protease inhibitor on hemodynamic changes was studied in experimental acute pancreatitis. Pancreatitis was induced by the injection of autologous bile mixed with trypsin into the main pancreatic duct after ligating the accessory duct. Plasma beta-endorphin concentrations and cardiovascular function were measured. Seventeen dogs (control group) were given 10 ml/kg/hr of lactate Ringer's solution intravenously 1 hr before the induction of pancreatitis and throughout the experiment. Seven dogs (the low protease inhibitor group) were given an intravenous bolus injection of 0.4 mg/kg of a new synthetic protease inhibitor, E-3123 (4-(2-succiminido-ethylthio)4-geranidinobenzoate methanesulfate) 30 min after the induction of pancreatitis and then a continuous intravenous infusion at 3 micrograms/kg/min throughout the experiment. Seven dogs (the high protease inhibitor group) received an intravenous bolus injection of 3 mg/kg and a continuous intravenous infusion at 50 micrograms/kg/min of E-3123 according to the same method as in the low protease inhibitor group. The mortality rate during the experiment was 41% (7/17) in the control group, 28.5% (2/7) in the high protease inhibitor group and 0% in the low protease inhibitor group. The increase in the plasma beta-endorphin levels in the control group was statistically significant. When E-3123 was given 30 min after the induction of pancreatitis, the increase in the plasma beta-endorphin levels in the high protease inhibitor group was also found to be increased statistically significant, compared with preinduction levels, but the increase was statistically significantly lower than that in the control group. Plasma beta-endorphin levels in the low protease inhibitor group, however, did not increase.(ABSTRACT TRUNCATED AT 250 WORDS)

Renal microcirculation in experimental acute pancreatitis of dogs

In order to understand the mechanism of acute renal failure frequently observed in severe acute pancreatitis, renal microcirculation and renal hemodynamics were investigated during experimental acute pancreatitis in dogs induced by autologous bile and trypsin mixture into the pancreatic duct. Renal tissue blood flow (hydrogen gas clearance method), renal arterial blood flow, and cardiac output (transonic blood flow meter) were each measured for 5 h after induction of pancreatitis. The effect on renal hemodynamics of a new synthesized protease inhibitor--E-3123; 4-(2-succinimidoethylthio)phenyl-4-quanidinobenzoate methane sulfonate--intravenously infused at the rate of 3 mg/kg/h was also investigated. The mean blood pressure and pulse pressure decreased after induction of pancreatitis. Renal microcirculation and renal artery blood flow decreased during the experiment. However, in dogs with treated by E-3123, renal microcirculation was preserved during the first hour of the experiment and decreased gradually afterward, but it was significantly higher than that of the dogs without E-3123 during 3-5 h. The mean blood pressure and pulse pressure were preserved nearly at preoperative levels during the experimental period. We concluded that renal microcirculation decreased concomitantly with a deterioration of acute pancreatitis, and that the new pancreatic protease inhibitor E-3123 may have some beneficial effect to improve renal hemodynamics in the early period of acute pancreatitis.

Quantitative electron-microscopic analyses of pulpal nerve fibres in the mouse lower incisor after neonatal capsaicin treatment

A single dose of capsaicin (50 mg/kg) was injected subcutaneously into four mice on day 2 of life; four untreated mice were used as controls. Six months later, a drop of 30 microM capsaicin was instilled on to the cornea of all the mice and the number of times the eyes were wiped was counted to assess the effect of capsaicin on trigeminal sensory neurones. Ultrathin cross-sections were made of the apical pulp of the incisors on both sides of control (n = 8) and capsaicin-treated animals (n = 8). Electron micrographs of pulp nerves were taken and enlarged to a final magnification of x34,000. The numbers of unmyelinated axons in the pulps of all 16 incisors and of unmyelinated axons per Schwann cell in the pulps of four incisors each from the control and capsaicin-treated groups were counted. The short diameters of unmyelinated axons were measured with a computer-operated image analyser. The number of eye wipings was eight-fold less in the capsaicin-treated than in the normal group. This finding clearly indicated that capsaicin irreversibly affected the chemogenic nociceptive trigeminal neurones. The mean number of unmyelinated axons was 345 in controls and 217 (37.1% reduction) in capsaicin-treated animals. The number of unmyelinated axons of less than 0.6 microns dia was 41.5% less in capsaicin-treated mice than in controls. Thus, fine unmyelinated axons in the mouse incisor pulp are capsaicin sensitive, and they are assumed to be nociceptive fibres conveying pain stimuli from the tooth. Capsaicin affected Schwann cells, even those with few unmyelinated axons.(ABSTRACT TRUNCATED AT 250 WORDS)

A light and electron microscopic study on pulpal nerve fibers in the lower incisor of the mouse

Light and electron microscopic studies were made on pulpal nerve fibers in mouse lower incisors, typical continuously growing teeth. Serial sections, from the apex of the odontogenic sheath to the incisal edge of the apical foramen, were examined by light microscopy to identify myelinated fibers passing through the apical foramen. The fine structure of the pulpal nerves was examined by electron microscopy at three sites: 1) the level at the incisal edge of the apical foramen; 2) a level 5 mm incisal from the apex of the odontogenic sheath; and 3) the level where the incisor comes out of the alveolar bone. No myelinated fibers were found passing through the apical foramen; they were also lacking at the three levels of the pulp. At level 2, unmyelinated axons were seen in close contact with smooth muscle fibers of arterioles. At level 3, nerve fibers were difficult to distinguish from processes of fibroblasts and odontoblasts. Degenerating axons were present in Schwann cells, and fine unmyelinated axons running through the odontoblast cell layer were seen. Various types of unmyelinated axons were observed in the apical region (level 1). These axons were classified into 6 types on the basis of their fine structures: Type I, bundles of unmyelinated axons completely or partly ensheathed by Schwann cell cytoplasm (mature type); Type II, bundles of unmyelinated axons in a space formed by a Schwann cell membrane (regenerating type); Type III, bundles of unmyelinated axons ensheathed not by a Schwann cell, but merely by a basal lamina (regenerating type); Type IV, single axons in direct contact with the basal lamina (regenerating or terminal type); Type V, naked, electron-dense axons with many vesicles and mitochondria (growth cone-like type); and Type VI, electron opaque axons, due to loss of axonal organellae (degenerating type). The significance of these structures is discussed in relation to the continuous growth of the rodent incisor.

Age-dependent attenuation of the decrease of C fibers by capsaicin and its effects on responses to nociceptive stimuli

The effects of subcutaneous treatment of mice 10, 15, or 20 days (young) or 30 or 60 days (adult) of age with capsaicin on development of unmyelinated (C) fibers in the L4 dorsal roots were examined. The responses of the mice 2-4 months later to thermal (hot plate; 55 degrees C) and neurogenic plasma extravasative (chemogenic nociception) stimuli were evaluated. Capsaicin treatment 10 days after birth affected development of myelinated fibers significantly (7.9% reduction). Capsaicin treatment 10, 15, 20, and 30 days after birth reduced the number of C fibers 11.0-51.7% and even treatment 60 days after birth caused a significant decrease (10.0%) in the mean number of C fibers. The destruction of C fibers by capsaicin was attenuated during development, but individual differences in the reduction of C fibers were observed on and after 15 days of life and seemed to become more marked over time. Neurogenic plasma extravasation related to primary sensory neurons was decreased by capsaicin, irrespective of the time of treatment. In parallel with reduction of C fibers, hot-plate latency was increased significantly by treatment of young animals with capsaicin. These results suggest that the effect of capsaicin on thermal nociception is age-dependent and is correlated with decrease of C fibers. However, a marked increase in hot-plate latency did not always correspond to a marked decrease of C fibers. In contrast, the reduction of plasma extravasation was not age-dependent: Reduced extravasation of dye persisted during development.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of a new synthetic protease inhibitor on beta-endorphin release during acute pancreatitis in dogs

The effect on endogenous beta-endorphins of a new synthetic protease inhibitor was studied in acute pancreatitis. Pancreatitis was induced by the injection of autologous bile mixed with trypsin into the main pancreatic duct after ligation of the accessory duct. Plasma beta-endorphin concentrations and cardiovascular function were measured. Ten dogs (control group) were given 10 ml/kg/h of lactate Ringer's solution intravenously beginning 1 h before the induction of pancreatitis and continuing throughout the experiments. Six dogs received an intravenous infusion of 3 mg/kg/h of a new synthetic protease inhibitor, E-3123 (4-(2-succinimidoethylthio)4-geranidinobenzoate methanesuLfonate), in lactate Ringer's solution soon after the induction of pancreatitis. Plasma beta-endorphin concentrations in the control group increased significantly. However, plasma beta-endorphin levels in the protease inhibitor group did not increase as in the control group. The protease inhibitor infusion improved hypotension, myocardial depression, and plasma lactate, suggesting that the inhibitory effect of the protease inhibitor on beta-endorphin release contributed to the improvement.

GABAergic neurons in the mouse superficial dorsal horn with special emphasis on their relation to primary afferent central terminals

Immunocytochemical studies were carried out on the morphological relation between primary afferent central terminals (C-terminals) and GABAergic neurons in the mouse superficial dorsal horn. The superficial dorsal horn is composed of many synaptic glomeruli comprising two types: Type I with centrally located CI-terminals surrounded by several dendrites and few axonal endings, and Type II with centrally located CII-terminals surrounded by several dendrites and a few axonal endings. The CI-terminals are sinuous or scalloped with densely packed agranular synaptic vesicles, a few granular synaptic vesicles and mitochondria, and show an electron dense axoplasm, whereas the CII-terminals are large and round or rectangular with evenly distributed agranular synaptic vesicles, a number of granular synaptic vesicles and mitochondria, and show an electron opaque axoplasm. The immunoreaction of GABA was remarkable in the superficial laminae of the dorsal horn. Many interneuronal somata in the substantia gelatinosa showed GABAergic immunoreactivity. The immunoreaction was seen in the entire GABAergic neuroplasm, but not in the nucleus and its envelope. Most GABAergic features appeared as dendrites making postsynaptic contact with CI- or CII-terminals; i.e., numerous C-terminals made presynaptic contact with GABAergic dendrites. GABA immunoreactivity was seen over round synaptic vesicles and mitochondrial membranes. A few CII-terminals made presynaptic contact with GABAergic interneuronal somata. Previous physiological and anatomical studies have suggested that not only the cutaneous nociceptive primary afferent C-terminals but also mechanoreceptive primary afferent C-terminals make presynaptic contact with the GABAergic dendrites, boutons and soma. The presynaptic relation of these primary afferents with GABAergic neurons seems to provide morphological support for the essential feature of the gate control theory: primary afferent fibers may play a part in the modulation of nociceptive information via GABAergic neurons in the superficial dorsal horn. Small GABAergic terminals were found to make contact with blood capillaries suggesting the release of GABA into circulation.

Renal function in experimentally induced acute pancreatitis in dogs: how it is affected by the nephrotoxic substance in pancreatic exudate from ascitic fluid

Renal failure occurring in dogs during experimental acute pancreatitis and the effect on renal function of intravenous injections of ascitic fluid which accumulated during the acute pancreatitis were studied. Five hours after the induction of acute pancreatitis, the accumulation of 200 to 400 ml of ascitic fluid, and an elevation in hematocrit as well as a decreased mean arterial pressure were observed, which suggested hypovolemia due to plasma loss. At the same time, the renal blood flow, glomerular filtration rate, and urinary output decreased significantly. Hypovolemia was observed to be the main cause of renal failure in accordance with previous reports. When the sterile ascitic fluid was injected into healthy dogs, temporary hypotension was observed without changes in the hematocrit. However, the renal blood flow, glomerular filtration rate and urinary output decreased, together with an elevation in renal vascular resistance, even after the hypotension had returned to normal. This study shows that renal failure associated with acute pancreatitis occurred mainly as a direct result of hypovolemia but also that the sterile ascitic fluid contained nephrotoxic substances which were suspected to be unrelated to vasoactive substances or protease. Their removal is therefore necessary for the treatment and prevention of renal failure complicating acute pancreatitis.

Effect of a synthetic protease inhibitor (Fut-175) on coagulation abnormalities during experimental acute pancreatitis in dogs

The coagulation disturbance observed during severe acute pancreatitis before and after the infusion of a new synthetic low molecular weight protease inhibitor (Fut-175) was compared. The coagulo-fibrinolytic changes after acute pancreatitis was induced by the intraductal injection of an autologous bile and trypsin mixture showed decreased platelet counts, decreased plasma fibrinogen levels, prolonged partial prothrombin time and increased fibrinogen degradation products. In addition, markers of hypercoagulation showed increased fibrin-peptide A and decreased antithrombin III. The two markers of fibrinolysis showed increased B beta 15-42 immunoreactive peptide and decreased alpha 2 antiplasmin. After the infusion of Fut-175, the coagulo-fibrinolytic abnormalities, which were observed during severe acute pancreatitis without infusion of Fut-175, were improved. Furthermore, Fut-175 could suppress the rise in fibrino-peptide A and B beta 15-42 immunoreactive peptide and decrease in antithrombin III and alpha 2 antiplasmin. Thus, Fut-175 seems to be an effective inhibitor of protease-mediated hypercoagulation and fibrinolysis in severe acute pancreatitis.

The action of capsaicin on primary afferent central terminals in the superficial dorsal horn of newborn mice

Capsaicin was injected subcutaneously (50 mg/kg) into 10 mice on days 2 or 3 after birth, and 12 h, 3 and 5 days later the distribution and structure of degenerated primary afferent central axons or terminals (C-terminals) in the lumbar spinal dorsal horn were examined by electron microscopy. Degenerated terminal axons with dense or lamellar bodies or higher electron density were conspicuous 12 h after treatment with capsaicin. Severely degenerated unmyelinated axons, including dense or lamellar bodies engulfed by microglial cells, were numerous in the most superficial (marginal) layer, but rarely seen in the substantia gelatinosa. Two types of primary afferent central terminals in the substantia gelatinosa showed various extents of degeneration: small dark C-terminals (CI-terminals) with densely packed agranular synaptic vesicles, and large light ones (CII-terminals) with less dense agranular synaptic vesicles and a few granular synaptic vesicles. Thus, many central axon terminals of dorsal root ganglion (DRG) neurons that are sensitive to capsaicin enter the marginal layer and substantia gelatinosa. Degenerated primary afferent central axons or terminals markedly decreased in the superficial dorsal horn 3 and 5 days after capsaicin treatment, still, there were many degenerating DRG neurons at this time as shown by our previous study. Previously we also reported that fewer slightly degenerating unmyelinated dorsal root axons and small DRG neurons appear at 12 h and larger DRG neurons degenerate later than smaller ones after treatment with capsaicin. As a result, the discovery of many severely degenerated terminal axons in the superficial dorsal horn soon after treatment supports the idea that capsaicin first acts on the central terminals and that this is followed by damage to larger DRG neurons.