bluuebunny/crossref_metadata_2025_split huggingface dataset:
Differential Regulation of Prolactin Release and Lactotrope Proliferation during Pregnancy, Lactation and the Estrous Cycle
Authors: Yin Ping , Arita Jun 
Published: April 2003

The proestrous surge of prolactin (PRL) secretion and subsequent proliferation of lactotropes at estrus have been suggested to be induced by a common hypothalamic hormone. We investigated changes in lactotrope proliferation at other reproductive stages of female rats when PRL secretion was stimulated. To assess proliferative activity of lactotropes, incorporation of 5-bromo-2′-deoxyuridine (BrdU) into DNA was measured by double immunostaining for PRL and BrdU. BrdU-labeling indices, determined by BrdU injections at 10.00 h, revealed low levels of proliferative activity of lactotropes at the reproductive stages including diestrus, days 6 and 13 of pregnancy, and day 6 of lactation while high levels were detected on estrus and the day of parturition. When BrdU-labeling indices were determined at 3-hour intervals through day 6 of pregnancy to find an increase in lactotrope proliferation which might occur at times other than 10.00 h, proliferative activity of lactotropes remained at low levels with a slight increase in the afternoon. Such a diurnal change as observed in early pregnancy was not detected on day 13 of pregnancy. In contrast, short-interval determinations of BrdU-labeling indices during a period from day 20 of pregnancy to day 2 of lactation revealed a marked increase in proliferative activity on the day of parturition with a peak at 18.00 h, which was comparable to that observed at estrus. To investigate involvement of ovarian steroids in suppression of lactotrope proliferation as observed during early pregnancy and lactation, ovariectomized and pup-removed lactating rats were given one of treatment combinations of estradiol and suckling. In pup-removed lactating rats, estradiol treatment alone induced neither a PRL surge nor an increase in BrdU-labeling indices. Suckling stimuli, which were effective in increasing serum PRL concentrations irrespective of estradiol treatment, elicited a marked increase in BrdU-labeling indices in the presence of estradiol but not in its absence. These results suggest that proliferative activity of rat lactotropes does not necessarily correlate with PRL secretion during pregnancy and lactation. In contrast to PRL release, lactotrope proliferation requires both a hypophysiotropic stimulatory input from the hypothalamus and a sensitizing action of estradiol, an observation which may account for the fact that proliferation does not occur during pregnancy and lactation in spite of elevated PRL release.
Differential Orexigenic Effects of Hexarelin and Its Analogs in the Rat Hypothalamus: Indication for Multiple Growth Hormone Secretagogue Receptor Subtypes
Authors: Torsello Antonio , Locatelli Vittorio , Melis Maria Rosaria , Succu Salvatora , Spano Maria Sabrina , Deghenghi Romano , Müller Eugenio E. , Argiolas Antonio 
Published: April 2003

We have previously reported that hexarelin and some of its analogs, including EP 50885, stimulated GH secretion and feeding after systemic administration in the rat, whereas EP 40904 selectively stimulated food intake and EP 40737 only GH release. The precise mechanism of growth hormone-releasing peptides (GHRPs) actions is still unclear, but the integrity of the arcuate nucleus of the hypothalamus (ARC) appears crucial for their endocrine effects. To better characterize the site(s) and mechanisms(s) of the orexigenic action of GHRPs, we have investigated their effects after infusion into the arcuate, paraventricular, ventromedial and medial preoptic areas of the hypothalamus. Food intake was measured for 60 min following injection of the test compound (2 µg/rat). Hexarelin, EP 40904 and EP 50885 had significant orexigenic effects after injection into the ARC. A specific NPY antagonist significantly inhibited the effect of hexarelin, whereas a GHRH antagonist was ineffective. In the paraventricular nucleus, only EP 50885 stimulated feeding, whereas all peptides were ineffective in the ventromedial nucleus and medial preoptic area. Taken altogether, these results demonstrate that GHRPs are endowed with site-specific orexigenic actions and that endogenous NPY, but not GHRH, mediates these effects. The additional orexigenic action of EP 50885 in the paraventricular nucleus suggests the existence of a GHRP receptor subtype different from the already cloned one.
Regulation of Norepinephrine in the Medial Preoptic Area of Siberian Hamsters by Gonadal Steroids
Authors: Tomaselli Laura , Endoh Aya , Dodge James , Badura Lori L. 
Published: April 2003

Photoperiod has profound effects upon the neuroendocrine axis underlying reproductive physiology in seasonally breeding mammals. For long-day (LD) breeders, such as the Siberian hamster, exposure to a short-day (SD) photoperiod results in declines in circulating levels of gonadal steroids, luteinizing hormone (LH), and prolactin (PRL). The current study sought to investigate the effects of photoperiod and steroid levels on norepinephrine (NE), one of the major neurochemical regulators of gonadotropin-releasing hormone (GnRH) function. Since NE release within the medial preoptic area (mPOA) has been shown to stimulate the activity of GnRH cells, it was hypothesized that exposure to a short photoperiod would decrease NE levels. Furthermore, since gonadal steroids show negative feedback on GnRH function, it was hypothesized that gonadectomy would result in increased levels of NE. Adult male and female Siberian hamsters were gonadectomized and implanted with silastic capsules containing either cholesterol (C) or a mixture of estradiol (E) or testosterone (T). Microdialysis sampling within the mPOA was conducted after 8 weeks of exposure to either an LD or an SD photoperiod. Blood samples were analyzed for LH and PRL, while dialysis samples were analyzed for NE and its major metabolite 3-methoxy-4-hydroxyphenylglycol (MHPG). The results revealed significant suppression of LH and PRL by exposure to the SD photoperiod in both males and females. For LH, the steroid implants suppressed circulating hormone levels under both photoperiods, whereas for PRL, steroid treatment facilitated circulating levels. In contrast, there were no significant effects of photoperiod on NE or MHPG release for either males or females, but there was a significant decrease in extracellular levels of these neurochemicals in steroid-treated animals. These data suggest that photoperiodic modulation of GnRH neuronal function by NE is achieved largely through the indirect effects of photoperiod on circulating gonadal steroids.
Changes of the Inducible Heat Shock Protein 70 mRNA Level in Rat Retina After Ischemia and Reperfusion
Authors: Lewden O. , Garcher C. , Assem M. , Morales C. , Rochette L. , Bron A.M. 
Published: April 2003

The heat shock protein 70 (HSP-70) mRNA level was evaluated in Long Evans rat retinas after ischemia and after reperfusion following ischemia. Retinal ischemia was induced by ligation of the optic nerve and vessels. Rats were sacrificed after 90 min of ischemia or 120 min of reperfusion following ischemia. Retinas were dissected. Total mRNA was extracted and inducible HSP-70 (iHSP-70) gene expression was analyzed by quantification of transcripts using an RT-PCR assay. Results were expressed in arbitrary units as a ratio of the optical density of iHSP-70/β-actin electrophoretic bands. iHSP-70 gene expression was 0.220 ± 0.027 (n = 5), 0.502 ± 0.045 (n = 5) and 0.468 ± 0.032 (n = 5) for the sham-operated, ischemia only and ischemia and reperfusion groups, respectively. There was a statistically significant difference between the control and ischemia groups, and between the control and ischemia and reperfusion groups (p < 0.001), suggesting a rapid HSP-70 mRNA expression of the retina due to an ischemic injury.
Lens Transmission by Fluorophotometry after Brachytherapy and Thermotherapy of Choroidal Melanoma
Authors: Weenink Anneke C. , van Best Jaap A. , Oosterhuis Jendo A. , Keunen Jan E.E. 
Published: April 2003

We studied the effect of transpupillary thermotherapy (TTT) by a diode laser at 810 nm combined with episcleral ruthenium-106 plaque treatment (<sup>106</sup>Ru) on lens transparency in patients with choroidal melanoma. Lens transmission of blue-green light was measured by fluorophotometry in 17 patients treated with <sup>106</sup>Ru treatment and TTT (measured 0.3–6 years after treatment), 12 patients treated with <sup>106</sup>Ru alone (measured 1–9 years after treatment) and 25 age-matched healthy controls. Differences in lens transmission were not significant between treated and untreated fellow eyes (p > 0.15) nor between patient and control eyes (p > 0.25). TTT of choroidal melanoma combined with <sup>106</sup>Ru plaque irradiation did not have a significant effect on the lens transparency up to 6 years after treatment.
Neuronal Origin of the Transcorneal Electrically Evoked Response in Area 17 (Primary Visual Cortex) of Cats
Authors: Shimazu Kazuhiro , Miyake Yozo , Fukatsu Yasuhiro , Watanabe Satoru 
Published: April 2003

We investigated how the neuronal activity of the cells in area 17 of cats evoked by transcorneal electrical stimuli is associated with the transcorneal electrically evoked response (EER). Neuronal firings were associated with the negative components of the EER, N1 (9 ms latency) and N2 (20 ms latency). Excitation of a longer latency was suppressed and periodic firings were rarely found. These findings indicate that the early negative components of the EER consist of the synaptic activities over the discharge thresholds of cortical cells, and also suggest that inhibition in the visual cortex may affect the EER.
Down-Regulation of MHC Class II Expression on Bovine Retinal Pigment Epithelial Cells by Cytokines
Authors: Enzmann Volker , Stadler Margit , Wiedemann Peter , Kohen Leon 
Published: April 2003

To determine the effect of interleukin-10 (IL-10) and transforming growth factor-β (TGF-β) on the down-regulation of MHC class II antigens, bovine retinal pigment epithelial (RPE) cells were incubated with interferon-γ (IFN-γ) in different concentrations. Subsequently, the IFN-γ pretreated RPE cells were cultured with TGF-β or IL-10 in distinct concentrations and treatment modi. About 10% of native (totally untreated) RPE cells were positive for MHC class II antigens detected with immunocytostaining. Under the influence of IFN-γ (1,000 U/ml), the number of MHC class II-bearing cells increased to 49.9 ± 4.5% positive cells after 8 days’ incubation. Expression decreased under the most effective TGF-β treatment (5 ng/ml) to 2.0 ± 0.9% after 24 h incubation, and under similar IL-10 treatment (200 U/ml) to 3.8 ± 1.4% after 72 h. This decreasing number of the MHC class II-positive cells may be useful for various eye research studies and, more especially, to RPE cell transplantation in the future.
Effects of Intravitreal Injection of Botulinum Toxin on the Electroretinogram of Rats
Authors: Li Shaomin , Mizota Atsushi , Adachi-Usami Emiko 
Published: April 2003

The retinal toxicity of botulinum toxin A (BTA) was electroretinographically studied in rats. Sixteen rats were injected intravitreally with 10 ng of BTA. A response-amplitude series was recorded before and 1, 6, 13 and 21 days after the injection of BTA. BTA did not alter the amplitude and the peak latency of the a-wave. The amplitude of the b-wave was not changed except for 2 rats, in which the b-wave was diminished. The peak latency of the b-wave was significantly prolonged after injection of 10 ng BTA (p < 0.05). Except for these latter 2 rats, the results indicated that the dosage used therapeutically appears to have no deleterious effect on retinal integrity or function at least in the short term, but multiple injections or higher doses of BTA could alter retinal function.
Effect of Na-Hyaluronan on Stromal and Endothelial Healing in Experimental Corneal Alkali Wounds
Authors: Chung Jang-Hyun , Park Yoo-Kyung , Paek Soo-Min , Chong Young-Hae , Kim Won-Ki 
Published: April 2003

The healing of stroma and endothelium after a standardized corneal alkali wound was evaluated in sodium-hyaluronan (Na-HA)-treated eyes. Alkali wounds were produced in one eye of each rabbit by applying a 5.5-mm round filter paper soaked in 1 <i>N</i> NaOH onto the central cornea for 60 s. Eyes were then treated with either 1% Na-HA (the treatment group) or phosphate-buffered saline (the control group) 4 times per day for 3 weeks. Endothelial wound morphometry was performed after alizarin red and trypan blue staining, while stromal healing was assessed by counting polymorphonuclear leukocytes (PMNs) and keratocytes in the central and marginal wound areas. During the early healing period the stroma treated with Na-HA had less PMNs than that of the control group. The size of the endothelial defect area measured 5 days after injury was significantly smaller in the Na-HA group than in the control corneas. The present findings indicate that topically applied 1% Na-HA affects stromal and endothelial healing during the early repair process after corneal alkali wounds.
The Effect of Propolis Extract in Experimental Chemical Corneal Injury
Authors: Öztürk Faruk , Kurt Emin , Çerçi Mehmet , Emiroglu Levent , İnan Übeyt , Türker Mehmet , Ilker Sami 
Published: April 2003

<i>Purpose:</i> To investigate the effect of propolis, a natural resin produced by honeybees, in the treatment of alkali-injured rabbit eyes. <i>Method:</i> A corneal alkali burn was induced by applying filter paper immersed in 1 <i>N</i> NaOH on the central axis of the right corneas of 24 rabbits for 30 s. The animals were divided into three treatment groups: group 1 (control) was given 0.3% tobramycin and phosphate-buffered solution; group 2 was treated with antibiotic coverage and topical 1% ethanolic extract of propolis; group 3 received antibiotic coverage and topical 1% dexamethasone. The dexamethasone-treated group was maintained as the positive control. Drugs were instilled 4 times a day for 7 days. The corneal inflammation was evaluated by calculating the average inflammatory index obtained from clinical observation of the ciliary hyperemia, central and peripheral corneal edema at 24 h, 48 h, on day 5 and day 7, before sacrificing the animals. Then, the corneas underwent routine histological examination. <i>Results:</i> The effects of dexamethasone and propolis on healing of injured corneas were similar (p > 0.05) and significantly better than controls at 24 h (p < 0.01, p < 0.05, respectively), and on day 7 (p < 0.05) with respect to the inflammatory index. On histological observation, inflammatory cell infiltration was lower as compared to control in both the dexamethasone and propolis groups (p < 0.001) and similar with each other (p > 0.05). <i>Conclusions:</i> Our study shows that propolis has an anti-inflammatory effect comparable to dexamethasone in chemical corneal injury.
Experimental Corneal Neovascularization by Basic Fibroblast Growth Factor Incorporated into Gelatin Hydrogel
Authors: Yang Cheng-Feng , Yasukawa Tsutomu , Kimura Hideya , Miyamoto Hideki , Honda Yoshihito , Tabata Yasuhiko , Ikada Yoshito , Ogura Yuichiro 
Published: April 2003

The study was designed to investigate the feasibility of using an acidic gelatin hydrogel as a biodegradable vehicle for basic fibroblast growth factor (bFGF). bFGF was incorporated by polyion complexation into a biodegradable hydrogel prepared by cross-linking acidic gelatin with the isoelectric point of 4.9. The dried hydrogel (sized to 2 × 1 mm) was hydrated with bFGF aqueous solution including different doses of bFGF (20, 50, 125, 250 and 500 ng) and implanted into a rabbit corneal pocket (2.5 × 2 mm). As a control group, the gelatin hydrogel without bFGF or bFGF alone (500 ng) was used. Corneal angiogenesis was evaluated by biomicroscopy, corneal fluorescein angiography and histology for 21 days. Photographs were taken and corneal angiogenesis was evaluated by image analysis. The hydrogel degraded with time after its implantation into the corneal pocket. Experimental eyes receiving the hydrogel containing more than 50 ng of bFGF demonstrated significant corneal angiogenesis. Control eyes and eyes receiving the hydrogel containing 20 ng of bFGF showed no corneal angiogenesis. Corneal angiogenesis, which occurred on the 3rd or 4th day after implantation, reached maximal growth on about day 7 and regressed from day 10 after implantation. The area of angiogenesis showed a dose-dependency on bFGF. The gelatin hydrogel itself induced neither angiogenesis nor inflammation. These results suggested that acidic gelatin hydrogel releases bioactive bFGF with its biodegradation, resulting in corneal neovascularization.
Effects of Nilvadipine, Nicardipine and Verapamil on Acute Rise of Aqueous Flare Induced by Iris Photocoagulation or Intravenous Lipopolysaccharides in Pigmented Rabbits
Authors: Zhang Xue-Yun , Hiraki Shigeyoshi , Kadoi Chiharu , Hayasaka Seiji 
Published: April 2003

The effects of nilvadipine, nicardipine and verapamil on the acute rise of aqueous flare induced by argon laser photocoagulation of the iris or by intravenous injection of lipopolysaccharides (LPS, 0.5 µg/kg) were investigated in pigmented rabbits. Nilvadipine, nicardipine and verapamil were injected intravenously. Aqueous flare was measured with a laser flare cell meter. Following photocoagulation, aqueous flare increased, reached its maximum at 45–75 min and then decreased. After administration of LPS, aqueous flare increased, reached its maximum at 4 h and then returned to baseline levels at about 24 h. Flare reactions were inhibited by nilvadipine in a dose-dependent manner. The elevations were maximally inhibited by nilvadipine 30 min before photocoagulation or intravenous LPS. Two hundred micrograms per kilogram of nilvadipine inhibited 81% of photocoagulation-induced flare elevation, while the same dose of nicardipine and verapamil inhibited 19 and 9% of the elevation, respectively. The same dose of nilvadipine inhibited 51% of LPS-induced flare elevation, while the same dose of nicardipine and verapamil inhibited 6 and 4% of the elevation, respectively. In conclusion, nilvadipine inhibited the experimental elevation of aqueous flare more effectively than did nicardipine and verapamil.
Immobilization Stress Induces Elevation of Intraocular Pressure in Rabbits
Authors: Miyazaki Yoshinori , Matsuo Toshihiko , Kurabayashi Yuzuru 
Published: April 2003

The aim of this study was to test whether immobilization and intravenous volume load as stressors influence the intraocular pressure in rabbits. Rabbits were immobilized for 1 h in a horizontally placed plastic tube with an internal diameter of 13.2 cm and a length of 33.2 cm. After immobilization, rabbits received rapid intravenous drip infusion of 5% glucose solution, 20 ml/kg of body weight, in 5 min. The intraocular pressure immediately after immobilization (11.2 ± 3.0 mm Hg; mean and standard deviation) was significantly higher compared to control rabbits without immobilization (9.2 ± 1.0 mm Hg, Student’s t test, p = 0.0462). This difference became significantly larger when volume load was exerted on both groups of rabbits (22.7 ± 5.6 versus 16.4 ± 2.2 mm Hg, p = 0.0067). Serum levels of cortisol, adrenaline, and noradrenaline were significantly elevated after immobilization (p = 0.0002, p = 0.0271, p = 0.0296, respectively). Venous pressure of the ear tended to increase in rabbits immediately after immobilization (15.8 ± 3.1 mm Hg) compared with control rabbits (8.5 ± 2.3 mm Hg), and the difference became significant when volume load was exerted on both groups of rabbits (20.8 ± 7.4 versus 9.2 ± 4.8 mm Hg, p = 0.0211). In conclusion, we clearly demonstrated that physical stress due to immobilization, especially in combination with volume load, increased intraocular pressure in rabbits.
Mineralocorticoid Hormone Signaling Regulates the ‘Epithelial Sodium Channel’ in Fibroblasts from Human Cornea
Authors: Mirshahi Massoud , Mirshahi Shahsultan , Golestaneh Nady , Nicolas Corinne , Mishal Zohar , Lounes Karim C. , Hecquet Christianne , Dagonet Françoise , Pouliquen Yves , Agarwal Manjul K. 
Published: April 2003

We investigated the regulation of sodium absorption by steroid hormones in embryologically diverse cells from the human eye. A cell extract from human corneal fibroblasts was positive for both the epithelial sodium channel (ENaC) and the mineralocorticoid receptor (MCR) as 82- to 85-kD and 102-kD bands, respectively, by the Western blot technique. In fluorescent, confocal and electron microscopy, the MCR was revealed as a nucleocytoplasmic protein, whereas the ENaC was almost exclusively membrane bound; both appeared aligned along actin filaments of corneal keratocytes, and both were widely colocalized in various cell types of human cornea in situ. Following reverse transcription and amplification of total RNA isolated from corneal fibroblasts, the ENaC and MCR genes in the PCR product were evident as predicted bands of 520 and 843 bp, respectively, whose sequence exhibited 100% identity with those from known human sources. The multiplication of corneal fibroblasts was influenced by both the MCR-specific antagonist RU 26752 and the natural hormone aldosterone, and these steroids also stimulated protein phosphorylation. In quantitative PCR, both the basal and aldosterone-induced levels of ENaC were diminished by the MCR-specific antagonist ZK 91587. Consequently, the ocular sodium channel appears to be regulated by steroid signalling in cells of diverse embryological origins, contrary to the existing notions where (a) this process would be limited exclusively to the epithelial cells and (b) ocular sodium transport would be regulated via the Na<sup>+</sup>-K<sup>+</sup>-ATPase in the basolateral membrane.
Histamine-Induced Increase in Isometric Tension of Smooth Muscle Is Mediated by Local Vagus Nerve in Human Bronchus
Authors: Aizawa H. , Inoue H. , Miyazaki N. , Hara N. 
Published: April 2003

<i>Background:</i> The vagus nerve is reported to play an important role in the regulation of airway responsiveness. <i>Objective:</i> In the present study, we investigated the role of the local vagus nerve in the changes in isometric tension of smooth muscle induced by histamine in the human airway. <i>Methods:</i> Eight human lung tissue specimens were obtained at thoracic surgery, and 24 bronchial smooth muscle strips were used for isometric tension recording. The changes in isometric tension were induced by histamine in the presence or absence of physostigmine (10<sup>–6</sup> <i>M</i>), atropine (10<sup>–6</sup> <i>M</i>), and/or tetrodotoxin (10<sup>–6</sup> <i>M</i>). <i>Results:</i> We found that: (1) histamine induced a dose-dependent increase in the isometric tension in human bronchial smooth muscle; (2) physostigmine (10<sup>–6</sup> <i>M</i>) significantly potentiated the amplitude of the histamine-induced increase in isometric tension; (3) atropine (10<sup>–6</sup> <i>M</i>) significantly suppressed the histamine-induced increase in isometric tension; (4) tetrodotoxin (10<sup>–6</sup> <i>M</i>), did not affect the histamine-induced increase in isometric tension of smooth muscle, and (5) in the presence of tetrodotoxin, atropine significantly suppressed the histamine-induced increase in isometric tension. <i>Conclusion:</i> These findings suggest that the histamine-induced increase in isometric tension is mediated partly by acetylcholine, presumably released by the direct action of histamine on the vagus efferent nerve terminals without the central reflex via vagus nerve.