Potential chemoprevention of diethylnitrosamine-induced hepatocarcinogenesis in rats: myrrh (Commiphora molmol) vs. turmeric (Curcuma longa)

The aim of the present study was to assess the potential chemopreventive effects of myrrh (Commiphora molmol) vs. turmeric (Curcuma longa) in hepatocarcinogenic rats induced by a single intraperitoneal injection of diethylnitrosamine (DENA) (200 mg/kg body weight). Ninety male Wistar rats used in this study were randomly divided into six equal groups (n = 15). Group 1 rats served as negative controls; group 2 received a single i.p. injection of DENA and served as positive controls. Rats in both groups were fed on basal diet. Group 3 rats were fed a diet containing 5% turmeric, whereas group 4 rats were fed a diet containing 2% myrrh. Rats in groups 5 and 6 received a single i.p. injection of DENA and were fed diets containing 5% turmeric and 2% myrrh, respectively. The study demonstrated that DENA caused a significant increase in serum indices of liver enzymes and also severe histological and immunohistochemical changes in hepatic tissues. These included disorganized hepatic parenchyma, appearance of pseudoacinar and trabecular arrays of hepatocytes and alterations in CD10-immunoreactivity. Dietary supplementation of turmeric relatively improved the biochemical parameters to values approximating those of the negative controls and delayed the initiation of carcinogenesis. In contrast, myrrh did not improve the biochemical parameters or delay the hepatocarcinogenesis. Both turmeric and myrrh induced significant biochemical and histological changes in non-treated rats. In conclusion, DENA significantly changes the biological enzymatic activities in serum and the integrity of hepatic tissues. Phytochemicals with potential hepatoprotective effects must be applied cautiously owing to their potential hepatotoxicity.     

Development of a Wound Dressing Composed of a Hyaluronic Acid Sponge Containing Arginine

Spongy sheets composed of cross-linked high-molecular-weight (HMW) hyaluronic acid (HA) were prepared by freeze-drying an aqueous HMW-HA solution containing cross-linking agent (Group I). The Group I sheet was immersed into an aqueous low-molecular-weight (LMW) HA solution with or without L-arginine (Arg) and was then freeze-dried to prepare several types of spongy sheets (Groups II–V). The amount of Arg was 1.0 g, 0.5 g, 0.2 g and 0 g in Groups III, IV, V and II, respectively. In the first experiment, each spongy sheet was applied to a full-thickness skin defect with a diameter of 35 mm in the abdominal region of SD rats, with intact skin in the central area measuring 15 mm in diameter. Commercially available polyurethane film dressing was applied over each spongy sheet as a covering material. The control group was covered with polyurethane film dressing alone. All spongy sheets promoted epithelization, as well as angiogenesis, as compared with controls. These findings indicate that HA and Arg are essential for wound healing. Re-epithelizaion was particularly active in Groups IV and V. In the second experiment, each spongy sheet was applied to a full-thickness burn injury measuring 35 mm in diameter in the abdominal region of SD rats, after necrotic skin was surgically removed. Groups II–V showed decreased wound size when compared with Group I and controls. The present findings indicate that the release of LMW-HA and Arg from a cross-linked HMW-HA spongy sheet effectively stimulates wound healing.     

Pathological reactions in lung, liver, thymus, and spleen of rats after subacute parenteral administration of nickel sulfate

Male Fischer-344 rats (10 to 12 rats per group) were given 14 i.m. injection of nickel sulfate (NiSO4) over a period of 26 days in order to delineate the two-year survival, body weight curves, hematocrit responses, and histopathological reactions, including carcinogenesis. Group A (vehicle controls) received the NaCl vehicle; Groups B, C, and D received NiSO4 solution at dosages of 63, 83, or 125 mumol per kg, respectively. Rats in Group D all died during the period from 4 to 32 days after the first injection; survival of rats in Groups B and C did not differ significantly from the controls (Group A). No differences were found at any time between the mean body weights or blood hematocrits of the NiSO4-treated groups vs. the controls. In Group D, histopathological lesions of the lung, liver, thymus, and spleen were consistently observed; these lesions were most severe in rats that died during the period from 22 to 32 days after the first injection. The lungs showed proliferation of alveolar lining cells, thickening of the alveolar wall, and proteinaceous alveolar exudate. The livers showed microvesicular steatosis, and necrotic hepatocytes were scattered throughout the lobules. Degeneration of lymphocytes, with pyknosis and karyorrhexis, was observed in the thymic cortex and the white pulp of the spleen. At necropsy, no significant differences were found between the NiSO4-treated rats of Groups B and C and the controls (Group A). No sarcomas or other neoplasms occurred near the injection sites in NiSO4-treated rats.(ABSTRACT TRUNCATED AT 250 WORDS)     

Airway responsiveness and bronchoalveolar lavage fluid profiling in individual rats: Effects of different ovalbumin exposures

We studied repeatedly the development of bronchial hyperreactivity (BHR) and bronchoalveolar lavage fluid (BALF) in rats undergoing different modes of ovalbumin exposures. Treatment was two intraperitoneal injections of ovalbumin in Groups 1-3, followed by one ovalbumin aerosolization in Groups 2 and 3, while rats in Group 4 received repeated ovalbumin aerosols after one single intraperitoneal injection. BHR was assessed longitudinally on day 0 (before treatment) and on day 14 (Groups 1 and 2) or 20 (Groups 3 and 4) and cellular influx was estimated from BALF. No BHR or change in BALF cellular profile was detected in Groups 1-3. However, the infiltration of inflammatory cells, associated with BHR (PC₁₀₀ 8.9 ± 1.3 μg/kg vs. 4.2 ± 1.1 μg/kg), was observed in Group 4. The BHR was always associated with increased number of eosinophils in the BALF. The substantial interindividual variability confirmed the need for a technique that permits follow-up of lung responsiveness and BALF profile. This approach evidenced strong associations between the severity of BHR and the eosinophilia.     

Robust axonal growth and a blunted macrophage response are associated with impaired functional recovery after spinal cord injury in the MRL/MpJ mouse

Spinal cord injury (SCI) in mammals leads to a robust inflammatory response followed by the formation of a glial and connective tissue scar that comprises a barrier to axonal regeneration. The inbred MRL/MpJ mouse strain exhibits reduced inflammation after peripheral injury and shows true regeneration without tissue scar formation following an ear punch wound. We hypothesized that following SCI, the unique genetic wound healing traits of this strain would result in reduced glial and connective tissue scar formation, increased axonal growth, and improved functional recovery. Adult MRL/MpJ and C57BL/6J mice were subjected to a mid-thoracic spinal contusion and the distribution of axon profiles and selected cellular and extracellular matrix components was compared at 1, 2, 4 and 6 weeks post-injury. Recovery of hind-limb locomotor function was assessed over the same time period. The MRL/MpJ mice exhibited robust axon growth within the lesion, beginning at 4 weeks post-injury. This growth was accompanied by reduced macrophage staining at 1, 2, 4 and 6 weeks post-injury, decreased chondroitin sulfate proteoglycan staining at 1-2 weeks and increased laminin staining throughout the lesion at 2-6 weeks post-injury. Paradoxically, the extent of locomotor recovery was impaired in the MRL/MpJ mice. Close examination of the chronic lesion site revealed evidence of ongoing degeneration both within and surrounding the lesion site. Thus, the regenerative genetic wound healing traits of the MRL/MpJ mice contribute to the evolution of a lesion environment that supports enhanced axon growth after SCI. However, this response occurs at the expense of meaningful functional recovery.     

Effect of nicotine treatment and withdrawal on random-pattern skin flaps in rats

BACKGROUND: Tobacco use is associated with a high incidence of skin necrosis after surgery. The ideal timing for the cessation of tobacco use before plastic surgery has not, however, been precisely determined. The aim of this work was to define the ideal duration of nicotine withdrawal prior to random-pattern skin flap surgery in rats. METHODS: Groups of 11 animals were subcutaneously injected with saline or nicotine (2mg/kg) twice a day and subjected to random-pattern skin flap surgery according to the following protocol: Group I: continuously injected with saline 4 weeks before and 1 week after the surgery; Group II: injected with nicotine for 4 weeks until the day of the surgery; Group III: injected with nicotine for 4 weeks until one day before the surgery; Group IV: injected with nicotine for 4 weeks until 5 days before the surgery; Group V: injected with nicotine for 4 weeks until 10 days before the surgery; Group VI: continuously injected with nicotine for 4 weeks before and 1 week after the surgery. McFARLANE skin flaps were performed on the dorsal skin, and the rats were sacrificed 1 week after the surgery. RESULTS: The necrotic area was smaller in group I (8.85cm(2)) than in group II (12.15cm(2)), III (12.88cm(2)) and VI (14.84cm(2)) (ANOVA p<0.0001). There was no difference between groups I, IV (10.13cm(2)) and V (9.27cm(2)). CONCLUSIONS: In conclusion, 5 days before surgery was considered the ideal time for nicotine withdrawal in this experimental model.     

Post-injury stretch promotes recovery in a rat model of muscle damage induced by lengthening contractions

We investigated the cellular mechanisms and therapeutic effect of post-injury stretch on the recovery process from muscle injury induced by lengthening contractions (LC). One day after LC, a single 15-min bout of muscle stretch was applied at an intensity of 3 mNm. The maximal isometric torque was measured before and at 2–21 days after LC. The myofiber size was analyzed at 21 days after LC. Developmental myosin heavy chain-immunoreactive (dMHC-ir) cells, a marker of regenerating myofibers, were observed in the early recovery stage (2–5 days after LC). We observed that LC-induced injury markedly decreased isometric torque and myofiber size, which recovered faster in rats that underwent stretch than in rats that did not. Regenerating myofiber with dMHC-ir cells was observed earlier in rats that underwent stretch. These results indicate that post-injury stretch may facilitate the regeneration and early formation of new myofibers, thereby promoting structural and functional recovery from LC-induced muscle injury.     

Histological and immunohistochemical study of the potential therapeutic impacts of bone marrow mesenchymal stem cells and exosomes for sciatic nerve crush injury model in rats

ABSTRACT

The aim was to evaluate the potential effect of bone marrow-derived mesenchymal stem cells (BMSC) and BMSC-EX in the sciatic nerve injury. Forty-five rats were divided into four groups, i.e. Group I control no surgery or treatment, Group II sciatic nerve crush surgery and 1 week post-surgery, Group III sciatic nerve crush injury was treated with BMSC, and Group IV sciatic nerve crush injury was treated with BMSC-EX. All animal groups were euthanized 2 weeks after treatment. Sciatic nerves were examined histologically and immunohistochemically. Group II showed various histological changes, i.e. vacuolation, degeneration and loss of nerve fibers. Group II showed a significant increase in collagen fibers, but with significant reduction in osmium tetroxide (OsO₄)-stained myelin sheaths and neurofilament immunostaining compared to Group I. Group II also revealed distortion and disruption of myelinated nerve fibers. Groups III and IV showed significant improvement of both histological and immunohistochemical changes in Group II. BMSC and BMSC-EX were shown to improve axonal regeneration.     

肝硬化大鼠模型肝细胞移植途径的筛选

目的 通过比较4种同种异体肝细胞移植方法治疗肝硬化大鼠模型的疗效,筛选出较好的细胞移植途径.方法 50只经证实成模的肝硬化大鼠模型动物被完全随机分为5组:肝动脉移植组(G1)、门静脉移植组(G2)、脾动脉移植组(G3)、尾静脉移植组(G4)及对照组(G5).前4组分别自肝动脉、门静脉、脾动脉及尾静脉注射肝细胞悬液2 ml(细胞数量为2×106),对照组(G5)不作干预.移植前后对各组大鼠行肝功能检测及术后处死大鼠取肝脏作病理评分.结果 G1、G2组移植后前3周血清白蛋白水平逐渐下降,第5周后逐渐回升,到第7周达到峰值[(15.4±2.3)g/L,(15.4±2.1)g/L].G1、G2组移植后前3周血清总胆红素水平逐渐上升,到第5周后逐渐回落,到第7周达到移植前的水平[(13.62±2.32)μmol/L].G5组移植前后血清总胆红素水平变化不明显;术后病理G3组改善最为明显,G1、G2组次之,G4组再次之,G5改善情况最差.结论 在针对肝硬化大鼠模型不同的移植途径中,经脾动脉途径移植肝细胞,术后病死率较低,能更有效地改善肝脏功能及减轻肝细胞的变性和坏死.     

Fibrin adhesive implant in wound healing repair of dental sockets with topical application of epsilon aminocaproic acid: histological analysis

The aim of the study was to evaluate wound healing repair of dental sockets after topical application of 5% epsilon-aminocaproic acid (EACA) and the use of fibrin adhesive implant in rats under anticoagulant therapy with warfarin. Sixty Albinus wistar rats were used, divided into three groups of 20. In Group I, the animals were given 0.1 mL/100 mg of 0.9% saline solution per day, beginning 6 days before dental extraction and continuing throughout the experimental period. In Group II, the animals received 0.03 mL of sodium warfarin daily, beginning 6 days before the surgery and continuing until the day of sacrifice; after tooth extractions, the sockets were filled with fibrin adhesive material. In Group III the animals were treated as in Group II, and after extractions, the sockets were irrigated with 5 mL of 5% EACA and filled with the same fibrin adhesive material. All groups presented biological phases of wound healing repair, the differences being evident only in the chronology. The results obtained in Group III were very similar to those of Group I in the last period of wound repair, whereas Group II presented a late chronology compared to the other groups.     

Metabolic activation of the brain of young rats after exposure to environmental complexity

Autoradiography with ¹⁴C-2-deoxyglucose was used to determine brain metabolic activity during the quiet period that follows after daily exploratory experiences in new complex environments. Eight 1-month-old, male Tryon rats were selected from two litters. Pairs of littermates matched by body weight were assigned to one of two conditions: rats housed individually in small home cages as the “impoverished condition,” or rats exposed twice daily to changing and complex environments of two large cages with inanimate objects and conspecifics as the “enriched condition.” After 4 days, rats were injected with 2-deoxyglucose, placed individually in a home cage and left undisturbed for 90 min until sacrificed. The brains of “enriched” rats were heavier than their “impoverished” littermates, and showed a global trend for metabolic enhancement. They also showed significantly greater amounts of 2-deoxyglucose in occipital cortex (27%), hippocampal subiculum (36%), and nucleus accumbens (40%).©1994 John Wiley & Sons, Inc.     

The oxidant and antioxidant effects of 25-hydroxyvitamin D3 in liver, kidney and heart tissues of diabetic rats

Previous studies have implicated protective effects of vitamin D on insulin secretion and pancreas beta cell function. The goal of the present study is to determine if a combination therapy of 25-hydroxyvitamin D3 and insulin had any advantage over insulin therapy alone on lipid peroxidation and antioxidant activity in the streptozotocin (STZ)-induced diabetic rat. The lipid peroxidation product, thiobarbituric acid-reacting substances (TBARS), was measured to assess free radical activity in the heart, kidney and liver tissues. The enzymatic activities of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and catalase (CAT) were measured as indicators of antioxidation in these tissues. Sprague-Dawley rats were made diabetic with a single injection of STZ (75 mg/kg i.p.). Rats were separated into three groups, each containing 10 animals: Group 1, non-diabetic and no drug treatment was given; Group 2, diabetic rats were treated with 3 IU/day subcutaneous (s.c.) insulin; and Group 3, diabetic rats were treated with 3 IU/day (s.c.) insulin plus 1 mg/kg/day per oral (p.o.) 25-hydroxyvitamin D3 for a period of 4 weeks. At the end of the study, TBARS contents of the liver, kidney and heart tissues in Groups 2 and 3 were found to be significantly increased as compared to Group 1 (P<0.05) and kidney MDA levels in Group 3 were also significantly increased as compared to Group 2 (P<0.05). The SOD and CAT contents of the heart in Group 2 were significantly increased as compared to Groups 1 and 3 (P<0.05). GSH-Px activity was unaltered in all groups (P>0.05). We suggest that a combination of insulin with 25-hydroxyvitamin D3 treatment would not be more beneficial than the use of insulin alone in antioxidant defence of diabetic liver and kidney tissues.     

Consequences of serial cortical, hippocampal, and thalamic lesions and of different lengths of overtraining on the acquisition and retention of learning tasks

The ability of the rat brain to acquire or to retain specific learning tasks was tested under conditions of multiple lesions and widely different amounts of practice. Lesion targets were (a) the medial prefrontal and cingulate cortex, (b) the anterior and mediodorsal thalamus, and (c) the dorsal and ventral hippocampus. Rats were divided into seven groups. The first group received lesions of all three structural complexes prior to training in a delayed alternation and an active avoidance task. Groups 2-4 received lesions in different combinations of two of the three structural complexes prior to task acquisition. Group 5 first learned both tasks and then received the medial cortical lesion; thereafter it was retrained to criterion. Then, the thalamic lesion was made, and relearning was tested a second time. Finally, the hippocampal region was damaged, and a last relearning test was given. Groups 6 and 7 also first acquired both tasks; however, after that, they received 240 (Group 6) or 1,280 (Group 7) trials of overtraining. Following this, all three structural complexes were given lesions serially before relearning of the two tasks was tested. Nine of the ten animals of Group 1 failed to acquire the alternation task, but all learned the avoidance task. In Groups 2-4, all rats acquired both tasks. Postoperatively, rats of Group 5 were inferior to those of Group 6 in both tasks, and rats of Group 7 were the most successful animals of the last three groups. These results question the assumption that serial lesions with intermittent training between lesions have beneficial effects, and they also stress the importance of task practice, that is, of behavioral experience. It is argued that prolonged training will lead to a widely distributed storage of information within the brain. The process of wide diffusion of information will, however, be disturbed (or at least retarded) by lesions made shortly after task acquisition or task reacquisition (as was the case for animals of Group 5).     

Beneficial Effects of N-Acetyl Cysteine on Pancreas and Kidney Following Experimental Pancreatic Ischemia-Reperfusion in Rats

OBJECTIVE:

To evaluate the protective effects of N-acetyl cysteine on the pancreas and kidney after pancreatic ischemia reperfusion injury in a rat model.

METHODS AND MATERIALS:

Pancreatic ischemia reperfusion was performed in Wistar rats for 1 hour. Revascularization was achieved followed by 4 h of reperfusion. A total of 24 animals were divided into four groups: Group 1: sham; Group 2: pancreatic ischemia reperfusion without treatment; Group 3: pancreatic ischemia reperfusion plus N-acetyl cysteine intravenously; and Group 4: pancreatic ischemia reperfusion plus N-acetyl cysteine per os. Blood and tissue samples were collected after reperfusion.

RESULTS:

There were significant differences in amylase levels between Group 1 (6.11±0.55) and Group 2 (10.30±0.50) [p=0.0002] as well as between Group 2 (10.30±0.50) and Group 4 (7.82±0.38) [p=0.003]; creatinine levels between Group 1 (0.52 ± 0.07) and Group 2 (0.77±0.18) [p=0.035] as well as between Group 2 (0.77±0.18) and Group 3 (0.48±0.13) [p=0.012]; and pancreatic tissue thiobarbituric acid reactive substance levels between Group 1 (1.27±0.96) and Group 2 (2.60±3.01) [p=0.026] as well as between Group 2 (2.60±3.01) and Group 4 (0.52±0.56) [p=0.002]. A decrease in pancreatic tissue GST-α3 gene expression was observed in Group 2 in comparison to Group 1 (p =0.006), and an increase was observed in Groups 3 and 4 when compared to Group 2 (p= 0.025 and p=0.010, respectively).

CONCLUSION:

This study provides evidence that N-acetyl cysteine has a beneficial effect on pancreatic ischemia reperfusion injury and renal function in a rat model.     

Promotion of chemically induced rat esophageal tumorigenesis with post-initiation ethanol modification.

Post-initiation ethanol modification on N-nitrosomethylbenzylamine (NMBA)-induced rat esophageal carcinogenesis model was investigated in male, 6-week-old, F344 rats that received s.c. injections, 3 times per week, of 0.5 mg/kg NMBA for the first 5 weeks and then were treated with 0% (Group 1), 3.3% (Group 2), and 10% (Group 3) ethanol in the drinking water for up to 20 weeks. Group 4 received 10% ethanol without NMBA administration and Group 5 was maintained without any chemical treatment. There were no statistical differences in the incidence and multiplicity of esophageal tumors among Groups 1 to 3. However, the multiplicity of hyperplasias was statistically greater in Group 3 than in Groups 1 or 2. Esophageal epithelia of all rats in Groups 4 and 5 demonstrated a normal histology. BrdU labelling indices of tumors and hyperplasias in NMBA-treated groups were essentially similar, although cycline D1 was overexpressed to a greater extent in tumors and also hyperplasias of Group 3 than in Groups 1 or 2. The results indicated ethanol to exert weak promotion effects through cycline D1 overexpression on rat esophageal tumorigenesis initiated with NMBA.     

Engraftment of primates with G-CSF mobilized peripheral blood CD34+ progenitor cells expanded in G-CSF, SCF and MGDF decreases the duration and severity of neutropenia.

We used a primate model of autologous peripheral blood progenitor cell (PBPC) transplantation to study the effect of in vitro expansion on committed progenitor cell engraftment and marrow recovery after transplantation. Four groups of baboons were transplanted with enriched autologous CD34+ PBPC collected by apheresis after five days of G-CSF administration (100 microg/kg/day). Groups I and III were transplanted with cryopreserved CD34+ PBPC and Groups II and IV were transplanted with CD34+ PBPC that had been cultured for 10 days in Amgen-defined (serum free) medium and stimulated with G-CSF, megakaryocyte growth and development factor (MGDF), and stem cell factor each at 100 etag/ml. Group III and IV animals were administered G-CSF (100 microg/kg/day) and MGDF (25 microg/kg/day) after transplant, while animals in Groups I and II were not. For the cultured CD34+ PBPC from groups II and IV, the total cell numbers expanded 14.4 +/- 8.3 and 4.0 +/- 0.7-fold, respectively, and CFU-GM expanded 7.2 +/- 0.3 and 8.0 +/- 0.4-fold, respectively. All animals engrafted. If no growth factor support was given after transplant (Groups II and I), the recovery of WBC and platelet production after transplant was prolonged if cells had been cultured prior to transplant (Group II). Administration of post-transplant G-CSF and MGDF shortened the period of neutropenia (ANC < 500/microL) from 13 +/- 4 (Group I) to 10 +/- 4 (Group III) days for animals transplanted with non-expanded CD34+ PBPC. For animals transplanted with ex vivo-expanded CD34+ PBPC, post-transplant administration of G-CSF and MGDF shortened the duration of neutropenia from 14 +/- 2 (Group II) to 3 +/- 4 (Group IV) days. Recovery of platelet production was slower in all animals transplanted with expanded CD34+ PBPC regardless of post-transplant growth factor administration. Progenitor cells generated in vitro can contribute to early engraftment and mitigate neutropenia when growth factor support is administered post-transplant. Thrombocytopenia was not decreased despite evidence of expansion of megakaryocytes in cultured CD34+ populations.     

Renal cell carcinoma with mixed features of papillary and clear cell cytomorphology: a fluorescent in situ hybridization study

We performed fluorescent in situ hybridization (FISH) to investigate the numeric change of chromosomes 7, 17, and Y and loss of chromosome 3p in “papillary renal cell carcinomas (RCC) with extensive clear cell changes (CCC).” Consecutive cases of RCC over a 12-year period were reviewed to identify “papillary RCC with extensive CCC.” Immunostaining for cytokeratin 7 and alpha-methylacyl-CoA racemase (AMACR) and FISH for chromosomes 7, 17, Y, and 3p were applied. Of the total of 521 RCC retrieved, there were 49 RCC with papillary architecture and clear cell areas that could be divided into: Group 1 (12 cases), typical clear cell RCC with focal areas of papillary formation; Group 2 (28 cases), focal typical papillary RCC having papillary architecture with extensive CCC; and Group 3 (nine cases), RCC with an admixture of eosinophilic/clear cytoplasm and solid/papillary architecture. Group 1 showed negative immunoreactivity for CK7 and AMACR and absence of numeric chromosomal gain or loss of chromosomes 7/17 and Y. Groups 2 and 3 showed variable reactivity for CK7 and AMACR. Tumors in group 2 and five in group 3 showed trisomies of chromosomes 7 and/or 17 with or without loss of chromosome Y. Loss of small arm 3p was observed in groups 1 and 3 but not in group 2 tumors. In conclusion, papillary RCC may show phenotypical CCC mimicking clear cell RCC. In a small number of cases with mixed histopathological features, FISH is helpful in subtyping RCC.     

Ultrastructural evaluation of the radioprotective effects of melatonin against X-ray-induced skin damage in Albino rats

Our knowledge about the radioprotective effects of melatonin against X-ray-induced skin damage is still lacking. To examine these effects, an animal model of 60 Albino rats was used. The animals were divided into five groups: Group 1, nonirradiated; Group 2, X-ray irradiated (XRI, 8 Gy); Group 3, XRI pretreated with solvent (ethanol and phosphate-buffered saline); Group 4, nonirradiated group treated with melatonin; and Group 5, XRI pretreated with melatonin. The skin was evaluated for ultrastructural changes using transmission electron microscopy (TEM). When compared to the nonirradiated skin (Groups 1 and 4), XRI skin (Groups 2 and 3) showed features of both cell injury and increased metabolic activity. The former included changes such as condensation of the nuclei, vacuolization of the cytoplasm, dilatation of the rough endoplasmic reticulum, swelling of the mitochondria with cristolysis, destruction of the ribosomes and intermediate filaments, fragmentation of the keratohyaline granules and loss of the irregularity of the basal cell borders. The central cells of the sebaceous gland alveoli had larger irregular nuclei and few lipid droplets in their cytoplasm. The hair follicle cells had heterochromatic nuclei and less electron dense cytoplasm containing few complements of the organelles. The features of increased metabolic activity included increased euchromatin, irregularity of the nuclear membrane and increased branching of the melanocytes. Also, an increased number of the Birbeck granules were seen in the Langerhans cells. When compared to the irradiated skin (Groups 2 and 3), these changes were mild or absent in the skin of XRI animals pretreated with melatonin (Group 5). The ability of melatonin to minimize the injurious effects of XRI suggests a radioprotective role. The clinical ramifications of these observations warrant further studies.     

Intercellular communication within the rat anterior pituitary gland: V. Changes in cell-to-cell communications as a function of the timing of castration in male rats

Cell-to-cell communication by gap junctions was investigated in the male rat anterior pituitary gland following several experimental regimens involving castration. The regimens included the following animals: (1) Group 1, castrated at 10-day intervals from day 10 to 50 and sacrificed at 60 days of age; (2) Group 2, castrated every 10 days from days 10 to 50 and sacrificed 50 days after castration; (3) Group 3, castrated at 5 days of age and sacrificed every 10 days from day 10 to 60; or (4) Group 4, remained intact and sacrificed every 10 days from days 10 to 60. In all of the castrated animals, numerous so-called castration cells were scattered throughout the pars distalis of the pituitary gland, with occasional “signet ring cells” being observed. In Groups 1 and 2, the pattern of gap junction development and their number was no different from the intact control (Group 4). In contrast, the number of gap junctions in the animals castrated on day 5 remained very small even into adulthood. These data demonstrate that gonadal steroids are important in the intial development of gap junctions within the pituitary gland but are not necessary to sustain their presence once an animal becomes an adult. © 1993 Wiley-Liss, Inc.     

Excitotoxic injury to thoracolumbar gray matter alters sympathetic activation and thermal pain sensitivity

Studies of humans, monkeys and rodents have implicated combined gray and white matter damage as important for development of chronic pain following spinal cord injury (SCI). Below-level chronic pain and hyperalgesia following injury to the spinal white matter, including the spinothalamic tract (STT), can be enhanced by excitotoxic influences within the gray matter at the site of SCI. Also, excitotoxic injury of thoracic gray matter without interruption of the STT results in below-level heat hyperalgesia. The present study evaluates the possibility that thoracolumbar gray matter injury increases sensitivity to nociceptive heat stimulation by altering spinal sympathetic outflow. Thermal preferences of rats for heat (45 °C) versus cold (15 °C) were evaluated before and after thoracolumbar injections of quisqualic acid (QUIS). A pre-injury preference for heat changed to a post-injury preference for cold. Systemic activation of the sympathetic nervous system by restraint stress decreased the heat preference pre-injury and increased the cold preference post-injury. The heat aversive effect of stress was magnified and prolonged post-injury, compared to pre-injury. Also, peripheral sympathetic activation by nociceptive stimulation was evaluated pre- and post-injury by measuring thermal transfer through a hindpaw during stimulation with 44.5 °C. Skin temperature recordings revealed enhanced sympathetic activation by nociceptive heat stimulation following spinal QUIS injury. However, increased sympathetic activation with peripheral vasoconstriction should enhance cold aversion, in contrast to the observed increase in heat aversion. Thus, peripheral sympathetic vasoconstriction can be ruled out as a mechanism for heat hyperalgesia following excitotoxic gray matter injury.