The nucleotide sequence of the rat cytoplasmic beta-actin gene

Gene-specific oxidative lesions in aged rat brain detected by polymerase chain reaction inhibition assay

An exposure of isolated rat brain genomic DNA to oxidative stress in the form of iron salts (Fe2+) and ascorbate results in gene-specific DNA lesions detectable by a quantitative polymerase chain reaction (PCR) based assay in which PCR amplification efficiency of the affected genes (e.g. beta-actin and p53) is grossly impaired. Such oxidative DNA lesions are prevented by hydroxyl radical scavengers like mannitol (20 mM) and sodium benzoate (20 mM) or by the antioxidant enzyme catalase (50 microg/ml) present in the incubation mixture during exposure to Fe2+ and ascorbate. When brain DNA isolated from young (4-6 months of age) and aged (20-24 months of age) rats are analyzed similarly by the PCR based method, the amplification levels of beta-actin and p53 genes are noticeably decreased in the case of aged rat indicating an accumulation of gene-specific DNA lesions during brain aging.

Modulation of AP-1 mediated estrogenic response by ormeloxifene in rat uterus

Ormeloxifene is a selective estrogen receptor modulator that exerts antiestrogenic effects and thereby inhibits growth in uterus. The present study was undertaken to examine the AP-1 protein interaction with AP-1 enhancer DNA elements in rat uterus in vivo and in vitro with a view to explore the modulation of estrogen action mediated via alternative pathway under the influence of ormeloxifene (Orm). In addition, the changes in expression of c-fos and c-jun transcription factors and mRNA expression of growth factor (IGF-1) were investigated with a view to assess the AP-1 mediated transcription. Ovariectomizedoung adult rats were administered with estradiol-17beta (5 microg/100 g body weight) or Orm (200 microg/100 g body weight) or vehicle for 3 days and sacrificed on fourth day. Electrophoretic mobility shift assay using uterine nuclear fraction from various treatment groups demonstrated that Orm caused a significant reduction in E2 induced AP-1 DNA binding. In vitro study revealed that Orm promotes AP-1 complex formation whereas its 7-hydroxy derivative inhibits it significantly. Uterine expression of c-fos and c-jun was increased significantly in Orm treated rats as compared to vehicle treated rats. However, the expression of c-fos and c-jun was decreased in rats receiving Orm plus E2. Semi-quantitative RT-PCR analysis revealed that mRNA expression of IGF-1 was increased in E2 treated group as compared to control group whereas reduced expression was observed in Orm treated rats as compared to E2 treated rats. The uterine weight and IGF-1 mRNA showed similar pattern, indicating that IGF-1 is involved in regulation of uterine weight. These results indicate that 7-hydroxy ormeloxifene (an active metabolite of Orm) is a potent antagonist at AP-1 sites. It inhibits the function of AP-1 transcription factors rather than their expression as evident by downregulation of mRNA expression of AP-1 regulated gene IGF-1, thereby inhibits proliferation in rat uterus. Study suggested a non-classicalregulation of estrogen action on uterus by ormeloxifene.

Catalase overexpression attenuates angiotensinogen expression and apoptosis in diabetic mice

Increased generation of reactive oxygen species (ROS) leads to oxidative stress in diabetes. Catalase is a highly conserved heme-containing protein that reduces hydrogen peroxide to water and oxygen and is an important factor decreasing cellular injury owing to oxidative stress. Hyperglycemic conditions increase oxidative stress and angiotensinogen gene expression. Angiotensinogen conversion to angiotensin II leads to a furtherance in oxidative stress through increased generation of reactive oxygen species. In this study, we utilized mice transgenically overexpressing rat catalase in a kidney-specific manner to determine the impact on ROS, angiotensinogen and apoptotic gene expression in proximal tubule cells of diabetic animals. Proximal tubules isolated from wild-type and transgenic animals without or with streptozotocin-induced diabetes were incubated in low glucose media in the absence or presence of angiotensin II or in a high-glucose media. Our results show that the overexpression of catalase prevents the stimulation of ROS and angiotensinogen mRNA in tubules owing to elevated glucose or angiotensin II in vitro. Additionally, overexpression of catalase attenuated ROS generation, angiotensinogen and proapoptotic gene expression and apoptosis in the kidneys of diabetic mice in vivo. Our studies point to an important role of ROS in the pathophysiology of diabetic nephropathy.

Expression of steroidogenic enzymes and synthesis of sex steroid hormones from DHEA in skeletal muscle of rats

The functional importance of sex steroid hormones (testosterone and estrogens), derived from extragonadal tissues, has recently gained significant appreciation. Circulating dehydroepiandrosterone (DHEA) is peripherally taken up and converted to testosterone by 3beta-hydroxysteroid dehydrogenase (HSD) and 17beta-HSD, and testosterone in turn is irreversibly converted to estrogens by aromatase cytochrome P-450 (P450arom). Although sex steroid hormones have been implicated in skeletal muscle regulation and adaptation, it is unclear whether skeletal muscles have a local steroidogenic enzymatic machinery capable of metabolizing circulating DHEA. Thus, here, we investigate whether the three key steroidogenic enzymes (3beta-HSD, 17beta-HSD, and P450arom) are present in the skeletal muscle and are capable of generating sex steroid hormones. Consistent with our hypothesis, the present study demonstrates mRNA and protein expression of these enzymes in the skeletal muscle cells of rats both in vivo and in culture (in vitro). Importantly, we also show an intracellular formation of testosterone and estradiol from DHEA or testosterone in cultured muscle cells in a dose-dependent manner. These findings are novel and important in that they provide the first evidence showing that skeletal muscles are capable of locally synthesizing sex steroid hormones from circulating DHEA or testosterone.

Expression of oestrogen receptors alpha and beta during the period of uterine receptivity in rat: effect of ormeloxifene, a selective oestrogen receptor modulator

AIMS

In the present study, we investigated expression, distribution and regulation of oestrogen receptors (ERs) alpha and beta and their modulation by ormeloxifene (Orm) during the period of uterine receptivity in rat uterus in order to determine their role in endometrial sensitization.

METHODS

Uterine tissues of control and Orm-treated (1.25 mg kg(-1), orally) rats were collected on days 3, 4, 5 morning and day 5 evening post-coitum referring to non-receptive, pre-receptive and receptive phases respectively. mRNA and protein expression levels were determined by RT-PCR and Western blot respectively. Immunohistochemical technique was used to localize the receptors.

RESULTS

RT-PCR analysis revealed that ERalpha mRNA reached a peak level on day 5 morning whereas ERbeta mRNA expression was found to be very low. In Orm-treated rats, the ERalpha mRNA was suppressed at day 5. The protein expression of ERalpha increased after day 3 and that of ERbeta remained very low throughout the pre-implantation period; Orm caused a decrease in ERalpha on day 5 morning. In endometrium, ERalpha expression was regulated differentially in luminal epithelium, glandular epithelium and stroma. Orm caused a decrease in the percentage of ERalpha-positive nuclei in all the three endometrial compartments on days 4 and 5, and the magnitude of reduction varied spatio-temporally. In case of ERbeta, immunostaining was not detectable in Orm-treated and control groups.

CONCLUSION

It appears that the complex uterine response to implantation is governed by differential cell-specific ERalpha expression. The study suggested the inhibitory activity of Orm on ERalpha during the period of uterine receptivity.

Thrombin inhibits aquaporin 4 expression through protein kinase C-dependent pathway in cultured astrocytes

Aquaporin 4 (AQP4) is a key molecule for maintaining water balance in the central nervous system, and its dysfunction might cause brain edema. However, little is known about the regulation of AQP4 expression. Because thrombin has been implicated in brain edema formation, the purpose of this study is to determine whether thrombin affects expression of AQP4 in astrocytes. Here, the effect of thrombin on AQP4 expression in vitro was evaluated using Western blot analysis and RT-PCR. Meanwhile, we investigated whether the effect of thrombin on AQP4 expression was due to protease-activated receptor 1 (PAR-1). In addition, we examined the role of protein kinase C (PKC) in the effect of thrombin on AQP4 expression using Western blot analysis. We found that thrombin did not affect cell viability at concentrations of 0.05, 0.5, 5, or 50 nM but killed astrocytes at concentrations of 500 nM, with approx 72% of astrocytes surviving at 500 nM thrombin. Our data showed that AQP4 protein expression achieved only 28% of controls in 500 nM thrombin treatment, even if astrocytes survived approx 72% of controls at 500 nM thrombin. Thrombin significantly inhibited AQP4 in a time- and dose dependent manner in vitro (p<0.05). Cathepsin-G, a thrombin PAR-1 inhibitor, reversed significantly (p<0.05) the effect of thrombin on AQP4 mRNA and protein expression in astrocytes. We also observed that PKC inhibitor H-7 or prolonged pretreatment with TPA can rapidly increase AQP4 expression (p<0.05). Thrombin might inhibit AQP4 expression in rat astrocytes, and this effect is possibly mediated by the PKC pathway.

HO-1 Mediates the Effects of HBO Pretreatment Against Sepsis

BACKGROUND

We have recently shown that attenuation of sepsis-induced lung injury by hyperbaric oxygen (HBO) pretreatment involves expression regulation of inducible nitric oxide synthase (iNOS) and heme oxygenase (HO)-1. This study was performed to determine the effects of HBO pretreatment on acute kidney and liver injuries in septic rats and the roles of iNOS and HO-1.

MATERIALS AND METHODS

One group of adult male rats (n = 48) were pretreated with HBO. The other group of rats (n = 48) breathed air at normal atmospheric pressure instead. Rats in each group were randomly allocated to receive injection of lipopolysaccharide (LPS), normal saline (N/S), LPS plus hemin (a HO-1 inducer), hemin, LPS plus SnPP (a HO-1 inhibitor), SnPP, LPS plus hemin plus SnPP, or hemin plus SnPP. Hemin and SnPP were injected at 1 h before HBO or air pretreatment. Rats were maintained for 6 h before sacrifice.

RESULTS

LPS caused prominent kidney and liver injuries as well as iNOS and HO-1 expression in stimulated rats. HBO pretreatment significantly attenuated LPS-induced kidney but not liver injury. However, in conjunction with hemin (a HO-1 inducer), HBO pretreatment did attenuate LPS-induced liver injury. In addition, the inhibition of iNOS expression by HBO pretreatment was associated with "super-induction" (i.e., further enhancement) of LPS-induced HO-1 expression. Furthermore, the therapeutic effect of HBO could be counteracted by SnPP (a HO-1 inhibitor).

CONCLUSIONS

HBO pretreatment significantly attenuates LPS-induced acute organ injuries in septic rats. The beneficial effect of HBO pretreatment against sepsis is mediated, at least in part, by "super-induction" of HO-1.

Modulation of estrogen receptor transactivation and estrogen-induced gene expression by ormeloxifene-a triphenylethylene derivative

The study was aimed to investigate the interaction of D,L-ormeloxifene (Orm), a triphenylethylene and its hydroxy derivative with estrogen receptor subtypes alpha and beta, its influence on ERE-driven transcriptional activation and progesterone receptor expression. In competitive binding experiments using human recombinant ERalpha and ERbeta, Orm showed interaction with both ER subtypes, with more selectivity and higher affinity towards ERalpha (8.8%) as compared to ERbeta (3%). In case of 7-hydroxy derivative, the relative binding affinity for both ERs was enhanced several folds. Orm showed lower Ki, i.e. higher affinity for ERalpha (250 nM) than for ERbeta (750 nM). It was observed that Orm promoted the formation of ER-ERE complexes in uterine tissue extract whereas its hydroxy derivative showed inhibitory effects. Transient co-transfection assay in COS-1 cells using ERE-luciferase reporter construct, revealed that Orm showed estrogenic response whereas its hydroxy-derivative was potent antiestrogen at ERalpha at transcription level. In immature rats, Orm (2 mg/kg) was associated with less increase in uterine weight and in luminal epithelial cell height than E2 or Tam. Orm also induced the expression of PR mRNA but the expression level was significantly less than estradiol treated group. These results suggest that ER-ERE complexes formed under the influence of 7-hydroxy Orm appear to be transcriptionally less effective hence antagonizing the E2-regulated gene expression in this target tissue.

Transforming growth factor-beta 1 stimulates angiotensinogen gene expression in kidney proximal tubular cells

The present study investigated whether transforming growth factor-beta 1 (TGF-beta1) exerts an autocrine positive effect on angiotensinogen (ANG) gene expression in rat kidney proximal tubular cells, and delineates its underlying mechanism(s) of action. Rat immortalized renal proximal tubular cells (IRPTCs) and freshly isolated mouse renal proximal tubules were incubated in the absence or presence of active human TGF-beta1. IRPTCs were also stably transfected with rat TGF-beta1 or p53 tumor suppressor protein (p53) cDNA in sense (S) and antisense (AS) orientations. ANG mRNA and p53 protein expression were assessed by reverse transcription-polymerase chain reaction and Western blotting, respectively. Reactive oxygen species (ROS) generation was quantified by lucigenin assay. Active TGF-beta1 evoked ROS generation and stimulated ANG mRNA and p53 protein expression, whereas a superoxide scavenger and inhibitors of nicotinamide adenine dinucleotide oxidase and p38 mitogen-activated protein kinase (p38 MAPK) abolished the TGF-beta1 effect. Stable transfer of p53 cDNA (S) enhanced and p53 cDNA (AS) abolished the stimulatory effect of TGF-beta1 on ANG mRNA expression in IRPTCs. Our results demonstrate that TGF-beta1 stimulates ANG gene expression and its action is mediated, at least in part, via ROS generation, p38 MAPK activation, and p53 expression, suggesting that angiotensin II and TGF-beta1 may form a positive feedback loop to enhance their respective gene expression, leading to renal injury.

Heterogeneous Nuclear Ribonucleoprotein K Modulates Angiotensinogen Gene Expression in Kidney Cells

The present studies aimed to identify the 70-kDa nuclear protein that binds to an insulin-responsive element in the rat angiotensinogen gene promoter and to define its action on angiotensinogen gene expression. Nuclear proteins were isolated from rat kidney proximal tubular cells and subjected to two-dimensional electrophoresis. The 70-kDa nuclear protein was detected by Southwestern blotting and subsequently identified by mass spectrometry, which revealed that it was identical to 65-kDa heterogeneous nuclear ribonucleoprotein K (hnRNP K). hnRNP K bound to the insulin-responsive element of the rat angiotensinogen gene was revealed by a gel mobility shift assay and chromatin immunoprecipitation assay. hnRNP K inhibited angiotensinogen mRNA expression and promoter activity. In contrast, hnRNP K down-expression by small interference RNA enhanced angiotensinogen mRNA expression. Moreover, hnRNP K interacted with hnRNP F in pulldown and co-immunoprecipitation assays. Co-transfection of hnRNP K and hnRNP F further suppressed angiotensinogen mRNA expression. Finally, in vitro and in vivo studies demonstrated that high glucose increases and insulin inhibits hnRNP K expression in rat kidney proximal tubular cells. In conclusion, our experiments revealed that hnRNP K is a nuclear protein that binds to the insulin-responsive element of the rat angiotensinogen gene promoter and modulates angiotensinogen gene transcription in the kidney.

Guanosine promotes the up-regulation of inward rectifier potassium current mediated by Kir4.1 in cultured rat cortical astrocytes

Guanosine (Guo) is an endogenous neuroprotective molecule of the CNS, which has various acute and long-term effects on both neurones and astroglial cells. Whether Guo also modulates the activity/expression of ion channels involved in homeostatic control of extracellular potassium by the astrocytic syncytium is still unknown. Here we provide electrophysiological evidence that chronic exposure (48 h) to Guo (500 microm) promotes the functional expression of an inward rectifier K+ (Kir) conductance in primary cultured rat cortical astrocytes. Molecular screening indicated that Guo promotes the up-regulation of the Kir4.1 channel, the major component of the Kir current in astroglia in vivo. Furthermore, the properties of astrocytic Kir current overlapped those of the recombinant Kir4.1 channel expressed in a heterologous system, strongly suggesting that the Guo-induced Kir conductance is mainly gated by Kir4.1. In contrast, the expression levels of two other Kir channel proteins were either unchanged (Kir2.1) or decreased (Kir5.1). Finally, we showed that inhibition of translational process, but not depression of transcription, prevents the Guo-induced up-regulation of Kir4.1, indicating that this nucleoside acts through de novo protein synthesis. Because accumulating data indicate that down-regulation of astroglial Kir current contributes to the pathogenesis of neurodegenerative diseases associated with dysregulation of extracellular K+ homeostasis, these results support the notion that Guo might be a molecule of therapeutic interest for counteracting the detrimental effect of K+-buffering impairment of the astroglial syncytium that occurs in pathological conditions.

Acupuncture stimulation of ST-36 (Zusanli) significantly mitigates acute lung injury in lipopolysaccharide-stimulated rats

BACKGROUND

We sought to investigate the potential therapeutic effects of acupuncture stimulation of ST-36 (Zusanli) on endotoxemia-induced acute lung injury in lipopolysaccharide (LPS)-stimulated rats.

METHODS

Sixty rats were randomized into six groups (n = 10): (i) lipopolysaccharide (LPS) control group, (ii) normal saline (N/S) control group, (iii) LPS plus ST-36 group, (iv) N/S plus ST-36 group, (v) LPS plus sham point (Sham) group, and (vi) N/S plus Sham group. Manual acupuncture stimulation of ST-36 (designated as 'ST-36') or a 'non-acupoint' (designated as 'Sham') was performed in lightly immobilized rats for 30 min. Then, LPS injection was employed to induce sepsis. Rats were killed at 6 h after LPS injection and lung injury, nitric oxide (NO) biosynthesis and inducible NO synthase (iNOS) expression were assayed.

RESULTS

Significant lung injury, pulmonary iNOS expression and systemic and pulmonary NO biosynthesis were noted in the LPS groups. Rats in the LPS plus Sham group had lung injury, pulmonary iNOS expression, systemic and pulmonary NO biosynthesis similar to those observed in the LPS group. However, the degree of lung injury, pulmonary iNOS expression and pulmonary NO biosynthesis, but not systemic NO biosynthesis, were significantly attenuated in the LPS plus ST-36 group as compared with those in both the LPS group and the LPS plus Sham group.

CONCLUSION

Acupuncture stimulation of ST-36 may be effective as a prophylaxis measure against sepsis. However, results from this study do not support the use of acupuncture for the treatment of sepsis.

Region-Specific Interrelations between Apoptotic Proteins Expression and DNA Fragmentation in the Neonatal Rat Brain

DNA fragmentation, mRNA and protein levels of Bcl-XL, Bax and caspase-3 were determined to characterize interrelations between expression of these apoptotic markers in the neonatal brain regions. High DNA fragmentation intensity in the cortex was in consonance with the lowest Bcl-XL/Bax expression ratio, the highest procaspase-3 and active caspase-3 levels. Low and intermediate DNA fragmentation levels in the cerebellum and hippocampus respectively were also in a good agreement with apoptotic proteins expression in these structures. In the cortex, hippocampus and cerebellum DNA fragmentation intensity was proportional to the active caspase-3 level. In contrast to these structures, in the brainstem, the lowest level of this protease was accompanied by the highest intensity of DNA fragmentation among the brain regions studied. The data suggest that cell death normally occurring during early postnatal life could be realized in the developing brainstem via caspase-3-independent pathways in animals that express this protease.

Upregulation of osteopontin gene expression in diabetic rat proximal tubular cells revealed by microarray profiling

Progression of diabetic nephropathy appears directly related to renal tubulointerstitial injury, but the involved genes are incompletely delineated. To identify such genes, DNA microarray analysis was performed with RNA from renal proximal tubules (RPTs) of streptozotocin-induced diabetic Wistar rats, spontaneously diabetic BioBreeding rats, and rat immortalized renal proximal tubular cells (IRPTCs) exposed to high glucose (25 mM) medium for 2 weeks. Osteopontin (OPN) mRNA expression was quantified by real time-quantitative polymerase chain reaction (RT-qPCR) or conventional reverse transcriptase-polymerase chain reaction (RT-PCR). OPN mRNA expression was upregulated (5-70-fold increase) in diabetic rat RPTs and in IRPTCs chronically exposed to high glucose compared to control RPTs and IRPTCs. High glucose, angiotensin II, phorbol 12-myristate 13-acetate and transforming growth factor-beta 1 (TGF-beta1) stimulated OPN mRNA expression in IRPTCs in a dose- and time-dependent manner. This effect was inhibited by tiron, taurine, diphenylene iodinium, losartan, perindopril, calphostin C, or LY 379196 but not PD123319. IRPTCs overexpressing dominant-negative protein kinase C-beta 1 (PKC-beta1) cDNA or antisense TGF-beta1 cDNA prevented the high glucose effect on OPN mRNA expression. We concluded that high glucose-mediated increases in OPN gene expression in diabetic rat RPTs and IRPTCs are mediated, at least in part, via reactive oxygen species generation, intrarenal rennin-angiotensin system activation, TGF-beta1 expression, and PKC-beta1 signaling.

Thiazolidinediones and rexinoids induce peroxisome proliferator-activated receptor-coactivator (PGC)-1alpha gene transcription: an autoregulatory loop controls PGC-1alpha expression in adipocytes via peroxisome proliferator-activated receptor-gamma coactivation

Thiazolidinediones (TZDs) are insulin-sensitizing drugs currently used to treat type 2 diabetes. They are activators of peroxisome proliferator-activated receptor (PPAR)-gamma, and adipose tissue constitutes a major site for their biological effects. PPAR coactivator (PGC)-1alpha is a transcriptional coactivator of PPARgamma and other transcription factors. It is involved in the control of mitochondrial biogenesis, and its activity has been linked to insulin sensitization. Here we report that PGC-1alpha gene expression in brown and white adipocytes is a direct target of TZDs via PPARgamma activation. Activators of the retinoid X receptor also induce PGC-1alpha gene expression. This is due to the presence of a PPARgamma-responsive element in the distal region of the PGC-1alpha gene promoter that binds PPARgamma/retinoid X receptor heterodimers. Moreover, there is a positive autoregulatory loop of control of the PGC-1alpha gene through coactivation of PPARgamma responsiveness to TZDs by PGC-1alpha itself. These data indicate that some of the effects of TZDs, especially promotion of mitochondrial biogenesis and oxidative pathways in adipose depots, entail PGC-1alpha up-regulation via enhanced transcription of the PGC-1alpha gene.

Exercise training improves aging-induced downregulation of VEGF angiogenic signaling cascade in hearts

Exercise training improves aging-induced deterioration of angiogenesis in the heart. However, the mechanisms underlying exercise-induced improvement of capillary density in the aged heart are unclear. Vascular endothelial growth factor (VEGF) is implicated in angiogenesis, which activated angiogenic signaling cascade through Akt and endothelial nitric oxide synthase (eNOS)-related pathway. We hypothesized that VEGF angiogenic signaling cascade in the heart contributes to a molecular mechanism of exercise training-induced improvement of capillary density in old age. With the use of hearts of sedentary young rats (4 mo old), sedentary aged rats (23 mo old), and exercise-trained aged rats (23 mo old, swim training for 8 wk), the present study investigated whether VEGF and VEGF-related angiogenic molecular expression in the aged heart is affected by exercise training. Total capillary density in the heart was significantly lower in the sedentary aged rats compared with the sedentary young rats, whereas that in the exercise-trained rat was significantly higher than the sedentary aged rats. The mRNA and protein expressions of VEGF and of fms-like tyrosine kinase-1 (Flt-1) and fetal liver kinase-1 (Flk-1), which are main VEGF receptors, in the heart were significantly lower in the sedentary aged rats compared with the sedentary young rats, whereas those in the exercise-trained rats were significantly higher than those in the sedentary aged rats. The phosphorylation of Akt protein and eNOS protein in the heart corresponded to the changes in the VEGF protein levels. These findings suggest that exercise training improves aging-induced downregulation of cardiac VEGF angiogenic signaling cascade, thereby contributing to the exercise training-induced improvement of angiogenesis in old age.

Effects of exercise training on pathological cardiac hypertrophy related gene expression and apoptosis

This study determined whether exercise training prevents pathological hypertrophy in the left ventricle by modulation of myocardial and apoptosis-associated genes. We used spontaneously hypertensive rats (n=15, non-exercise SHR), exercise-trained SHR (n=15, treadmill exercise for 12 weeks), and sedentary Wistar-Kyoto (WKY) rats (n=15). Exercise-trained SHR expressed adaptive changes such as reduced body weight, heart rate, blood pressures, left ventricle wall thickness, lipid profiles, and homocysteine level. The mRNA expression of angiotensin converting enzyme, endothelin-1, and brain natriuretic peptides in the heart was lower in the exercise-trained SHR and in the WKY than in the non-exercise SHR, whereas mRNA expression of caveolin-3 and eNOS in the heart was higher. Bcl-2 protein was higher in the exercise-trained SHR than in the WKY and the non-exercise SHR. In contrast, Bax protein levels were lower in the exercise-trained SHR and in the WKY than in the non-exercise SHR. Furthermore, the levels of the active forms of caspase-3 (20 kDa) were lower in the exercise-trained SHR and in the WKY than in the non-exercise SHR. These findings suggest that exercise training prevents pathological hypertrophy in the left ventricle by modulation of myocardial genes and that it interferes with a signal transduction pathway of apoptosis secondary to the pathological cardiac hypertrophy.

Induction of CYP1A1 in rat lung cells following in vivo and in vitro exposure to quartz

Respirable quartz has been classified as a human lung carcinogen, but the mechanism by which quartz exposure leads to lung cancer has not been clarified. Consistently higher risks of lung cancer are reported in smokers with quartz exposure and we therefore hypothesised that quartz exposure may alter the expression of enzyme systems involved in activation/detoxification of pre-carcinogens in cigarette smoke. More specifically we studied cytochrome P4501A1 (CYP1A1) expression using reverse transcriptase polymerase chain reaction and immunohistochemistry (IHC) upon in vitro and in vivo quartz exposure. In vitro incubation of rat lung epithelial cells with DQ12 quartz for 24 h showed a dose-dependent induction of CYP1A1-mRNA. On the other hand, CYP1A1 message was not increased in lung epithelial cells isolated from rats at 3, 28 or 90 days after intratracheal instillation of 2 mg DQ12. Following IHC for CYP1A1 protein in rat lung sections from later time-points (180 and 360 days), we observed an increase in the number of CYP1A1 positive cells. After in vivo quartz exposure, protein expression of the Aryl hydrocarbon receptor (AhR) was increased and nuclear translocation of AhR was observed at the same time-points. In conclusion, our findings demonstrate an effect of quartz exposure on chronic CYP1A1 expression in vivo, whereas the in vitro models show an immediate upregulation. We suggest that this upregulation of CYP1A1 may act as a co-carcinogenic pathway in quartz exposed workers by activation of pre-carcinogens such as those present in cigarette smoke.

RAS blockade decreases blood pressure and proteinuria in transgenic mice overexpressing rat angiotensinogen gene in the kidney

Angiotensinogen (ANG) is the sole substrate of the renin-angiotensin system (RAS). Clinical studies have shown that RAS activation may lead to hypertension, a major cardiovascular and renal risk factor. To delineate the underlying mechanisms of hypertension-induced nephropathy, we generated transgenic mice that overexpress rat ANG (rANG) in the kidney to establish whether intrarenal RAS activation alone can evoke hypertension and kidney damage and whether RAS blockade can reverse these effects. Transgenic mice overexpressing renal rANG were generated by employing the kidney-specific, androgen-regulated protein promoter linked to rANG cDNA. This promoter targets rANG cDNA to renal proximal tubules and responds to androgen stimulation. Transgenic mice displayed kidney-specific expression of rANG, significantly increased blood pressure (BP) and albuminuria in comparison to non-transgenic littermates. Administration of losartan (an angiotensin II (type 1)-receptor antagonist) or perindopril (an angiotensin-converting enzyme inhibitor) reversed these abnormalities in transgenic animals. Renal injury was evident on examination of the kidneys in transgenic mice, and attenuated by losartan and perindopril treatment. We conclude that the overproduction of ANG alone in the kidney induces an increase in systemic BP, proteinuria, and renal injury. RAS blockers prevent these abnormalities. These data support the role of the intrarenal RAS in the development of hypertension and renal injury.

Effects of maternal uninephrectomy on the development of fetal rat kidney: apoptosis and the expression of oncogenes

The present study was designed to explore whether maternal uninephrectomy affects development of the collecting ducts in fetal kidney. Localization of DNA fragmented cells in the kidney of fetal rats from uninephrectomized mothers were examined by the terminal deoxynucleotidyl transferase (TdT)-mediated d-UTP-biotin nick end labeling (TUNEL) method. Immunohistochemistry was used to examine the localizations of bcl-2 gene products. The gene expressions for bcl-2, p53, and WT1 mRNAs were examined by using the semi-quantitative reverse transcript-polymerase chain reaction. TUNEL positive cells were more numerous in the medullary collecting ducts of the fetuses from uninephrectomized mothers than in those of the fetuses from sham-operated ones. The expressions of bcl-2, p53, and WT1 mRNAs were lower in the fetuses from uninephrectomized mothers than in the fetuses from sham-operated ones. Cells in the medullary collecting ducts showed positive reactions to anti-bcl-2 gene products antibody with the reactions being weaker in the fetuses from uninephrectomized mothers. These results showed that maternal uninephrectomy accelerated the development of fetal rat kidney and it was associated with the lowered the expression of bcl-2 in fetal rat kidney.

Ghrelin-induced gastroprotection against ischemia-reperfusion injury involves an activation of sensory afferent nerves and hyperemia mediated by nitric oxide

Ghrelin has been recently identified as an endogenous ligand for growth hormone secretagogue receptor that regulates growth hormone secretion, increases appetite and contributes to energy homeostasis. Although this peptide is predominantly produced by the fasted stomach, little is known about its influence on the gastric mucosal integrity. The aim of the present study was (1) to investigate the effect of acylated ghrelin on the formation and healing of acute gastric mucosal lesions induced by ischemia-reperfusion and gastric mucosal blood flow in rats; (2) to analyse the effects of the deactivation of afferent sensory nerves with capsaicin and of the inhibition of nitric oxide (NO)-synthase by NG-nitro-l-arginine (l-NNA) on the ghrelin-induced protection; (3) to examine the influence of ghrelin on nuclear factor-kappa B (NF-kappaB) activation and on release of proinflammatory cytokines, such as tumor necrosis factor-alpha, (4) to assess the effect of ghrelin on the mRNA expression of constitutive nitric oxide synthase (cNOS), calcitonin gene related peptide (CGRP) and angiogenesis related proteins such as hypoxia inducible factor-1 alpha (HIF-1alpha) and vascular endothelial growth factor (VEGF), and (5) to determine the effect of ischemia/reperfusion on the gastric mucosa expression of ghrelin in rats without and with administration of exogenous hormone. Wistar rats were exposed to 30 min of ischemia followed by 3 h of reperfusion. Ghrelin was administered in dose of 5, 10 or 20 mug/kg intraperitoneally (i.p.) 30 min prior exposure to ischemia/reperfusion and at 3 h after the end of ischemia, the mean lesion area was measured by planimetry and the changes in gastric blood flow were determined by hydrogen (H2)-gas clearance method. The healing of ischemia/reperfusion induced lesions was evaluated at 24 h or 6 days after the end of standard ischemia/reperfusion. The expression of cNOS, CGRP, HIF-1alpha, VEGF and ghrelin was evaluated by reverse transcription polymerase chain reaction or Western blot. Ghrelin significantly attenuated the ischemia/reperfusion-induced gastric lesions and accelerated the healing of these lesions while significantly raising the gastric blood flow. Deactivation of sensory nerves with capsaicin or inhibition of cNOS by L-NNA significantly attenuated the protective activity of ghrelin and accompanying increase in the GBF. Exogenous ghrelin significantly inhibited the activation of NF-kappaB and plasma TNF-alpha levels. The ghrelin-enhanced acceleration of healing of ischemia/perfusion induced lesions was accompanied by enhanced expression of mRNA for HIF-1alpha and by diminution of the ischemia/reperfusion induced increase in mRNA expression for TNF-alpha. We conclude that ghrelin exerts a potent protective action on the gastric mucosa and accelerates the healing of ischemia/reperfusion-induced lesions and these effects depend upon activation of sensory nerves, hyperemia mediated by NO, increased angiogenesis due to expression of YEGF and anti-inflammatory properties of this peptide.

Effect of increased hepatic platelet activating factor and its receptor portal hypertension in CCl4-induced liver cirrhosis

AIM: To evaluate the changes in hepatic platelet activating factor (PAF) and its receptors and their effect on portal pressure of cirrhotic rats induced by CCl₄.

METHODS: A model of liver cirrhosis was replicated in rats by intra-peritoneal injection of CCl₄ for 8 wk. We determined the effect of hepatic PAF and its receptor level on portal and arterial pressure by EIA, saturation binding and RT-PCR technique.

RESULTS: Compared to control rats, cirrhotic rats had higher hepatic PAF levels and output as well as higher plasma PAF levels (P < 0.01, P < 0.01, P < 0.05, respectively). Both hepatic PAF receptor mRNA levels and PAF binding were nearly 3-fold greater in cirrhotic rats (P < 0.01). Portal injection of PAF (1 g/kg WT) increased the portal pressure by 22% and 33% in control and cirrhotic rats, respectively. In contrast, the arterial pressure was decreased in the both groups (54% in control rats and 42% in cirrhotic rats). Injection of the PAF antagonist BN52021 (5 mg/kg WT) decreased the portal pressure by 16% in cirrhotic rats but had no effect in the control rats.

CONCLUSION: The upregulation of the PAF system contributes to hepatic hemodynamic and metabolic abnormalities in cirrhosis, and the increased release of PAF into the circulation has impacts on the systemic hemodynamics.

Anti-fibroblast growth factor-2 antibodies attenuate mechanical allodynia in a rat model of neuropathic pain

Peripheral nerve injury leads to the activation of spinal cord astrocytes, which contribute to maintaining neuropathic (NP) pain behavior. Fibroblast growth factor-2 (FGF-2), a neurotrophic and gliogenic factor, is upregulated by spinal cord astrocytes in response to ligation of spinal nerves L5 and L6 (spinal nerve ligation [SpNL]). To evaluate the contribution of spinal astroglial FGF-2 to mechanical allodynia following SpNL, neutralizing antibodies to FGF-2 were injected intrathecally. Administration of 18 microg of anti-FGF-2 antibodies attenuated mechanical allodynia at day 21 after SpNL and reduced FGF-2 and glial acidic fibrillary protein mRNA expression and immunoreactivity in the L5 spinal cord segment of rats with SpNL. These results suggest that endogenous astroglial FGF-2 contributes to maintaining NP tactile allodynia associated with reactivity of spinal cord astrocytes and that inhibition of spinal FGF-2 ameliorates NP pain signs.

Dietary PUFA modulate the expression of proliferation and differentiation markers in Morris 3924A hepatoma cells

The effect of dietary polyunsaturated fatty acids on the expression of differentiation and proliferation markers in Morris 3924A hepatoma cells was investigated. ACT/I rats were conditioned 10 days with diets enriched with linoleic acid or alpha-linolenic acid before subcutaneous hepatoma cell transplantation. After 19 days from the inoculum, the mRNA levels of liver-enriched transcription factors and of their target genes were quantified. Both linoleic acid- and linolenic acid-enriched diets induced a decrease of beta-actin, AFP, PCNA, c-myc and of hepatocyte nuclear factors HNF-1alpha and HNF-4alpha mRNA levels in tumor tissue whereas HNF-3beta expression was induced by both dietary treatments. Only the alpha-linolenic acid-enriched diet was effective in reducing c-jun and increasing albumin mRNA levels. Since albumin is a C/EBPalpha target gene, C/EBPalpha gene transcription was evaluated at both protein and mRNA levels. It was found that alpha-linolenic acid-enriched diet did not enhance the C/EBPalpha mRNA content in hepatoma tissue while inducing C/EBPalpha protein expression with an isoform pattern similar to the hepatic phenotype. This evidence implies that alpha-linolenic acid or one of its metabolic products induce albumin synthesis in hepatoma cells by modulating C/EBPalpha gene expression at post-transcriptional level.

Chronic effects of AJ-9677 on energy expenditure and energy source utilization in rats

The effects of AJ-9677 on metabolic parameters were examined in rats that had or had not been chronically treated with this beta3-adrenoceptor agonist. A challenge administration of AJ-9677 increased both the temperature of brown adipose tissue and energy expenditure in both groups of rats. However, whereas the former effect was subject to desensitization, the latter effect was augmented by prior chronic administration of AJ-9677. Whereas a challenge administration of AJ-9677 induced a decrease in the respiratory quotient that persisted for at least 15 h in rats pretreated with vehicle, the initial decrease in this parameter lasted for only 4 h in rats pretreated with AJ-9677. These results suggest that, in rats subjected to chronic treatment with AJ-9677, a challenge administration of this drug increased energy expenditure by stimulation not only of fat oxidation but also of glucose oxidation.

Gene expression profiling of exercise-induced cardiac hypertrophy in rats

AIMS

Exercise training causes physiological cardiac hypertrophy, which acts to enhance cardiac function during exercise. However, the underlying molecular mechanisms are unclear. We investigated gene expression profile of exercise training-induced cardiac hypertrophy using left ventricle (LV) excised from exercise-trained and sedentary control rats (12-week old).

METHOD

Rats in the training group exercised on a treadmill for 8-week.

RESULTS

Left ventricular mass index and wall thickness in the exercise-trained group were significantly greater than that in the control group, indicating that the trained rats developed cardiac hypertrophy. Of the 3800 genes analysed in the microarray analyses, a total of 75 relevant genes (upregulation of 33 genes and downregulation of 42 genes) displayed alterations with exercise training. Among these genes, we focused on glycogen synthase kinase (GSK)-3beta, calcineurin-inhibitor (Cain), and endothelin (ET)-1 for their implicated roles in pathological cardiac hypertrophy, and confirmed the results of microarray analysis at mRNA and protein/peptide levels using quantitative PCR, Western blot, and EIA analyses. The gene expression of GSK-3beta decreased significantly and those of Cain and ET-1 increased significantly with exercise training. Furthermore, LV mass index was significantly correlated with GSK-3beta protein activity (r = -0.70, P < 0.01) and tissue ET-1 concentration (r = 0.52, P < 0.05). There were no changes in gene expressions in brain natriuretic peptide (BNP), angiotensin-correcting enzyme (ACE), interleukin-6, and vascular cell adhesion molecule (VCAM)-1.

CONCLUSION

These findings suggest that physiological and pathological LV hypertrophy may share some of the same molecular mechanisms in inducing LV hypertrophy (e.g. GSK-3beta, Cain, and ET-1) and that other genes (e.g. BNP, ACE) may differentiate physiological from pathological LV hypertrophy.

Hyperbaric oxygen attenuation of lipopolysaccharide-induced acute lung injury involves heme oxygenase-1

BACKGROUND

Hyperbaric oxygen (HBO) attenuates lipopolysaccharide (LPS)-induced acute lung injury. This beneficial effect of HBO involves inhibition of inducible nitric oxide synthase (iNOS) expression and subsequent nitric oxide (NO) biosynthesis. We sought to investigate the role of heme oxygenase-1 (HO-1) on this HBO inhibition of iNOS induction and acute lung injury in septic rat lungs.

METHODS

Before the experiment, 72 rats were randomly allocated to receive HBO or air treatment. With or without HBO pre-treatment, the rats were further divided into the following subgroups (n = 6): (i) LPS injection, (ii) normal saline (N/S) injection, (iii) hemin (a HO-1 inducer) plus LPS, (iv) hemin alone, (v) tin protoporphyrin (SnPP; a HO-1 inhibitor) plus LPS, and (vi) SnPP alone. All rats were maintained for 6 h and then sacrificed with a high-dose pentobarbital injection. Lung injuries and relevant enzymes expression were thus assayed.

RESULTS

Histological analysis, PMNs/alveoli ratio, and wet/dry weight ratio measurements demonstrated that LPS caused significant lung injury and HBO and/or hemin significantly attenuated this LPS-induced lung injury. Increased pulmonary iNOS expression and NO production were associated with lung injury. Induction of HO-1, by HBO and/or hemin, significantly attenuated this LPS-induced iNOS expression and acute lung injury. SnPP, on the contrary, offset the effects of HBO and worsened the LPS-induced lung injury.

CONCLUSIONS

HBO may act through inhibiting pulmonary iNOS expression to attenuate LPS-induced acute lung injury in septic rats. Furthermore, this HBO attenuation of iNOS expression involves HO-1 induction.

Aortic Stiffness and Aerobic Exercise: Mechanistic Insight from Microarray Analyses

INTRODUCTION/PURPOSE

Regular aerobic exercise reduces aortic stiffness. However, the mechanisms by which chronic exercise lowers arterial stiffness are not known. To determine the molecular mechanisms of these changes, the alteration of gene expression in the aorta by aerobic exercise training was measured with the microarray technique.

METHODS/RESULTS

The differences in expression levels of 3800 genes in the abdominal aorta of sedentary control rats (8 wk old) and exercise-trained rats (8 wk old, treadmill running for 4 wk) were compared by the microarray analysis. Aortic pulse wave velocity (PWV) was lower and systemic arterial compliance was higher (both P < 0.05) in the exercise-trained group than in the control group. Of the 323 genes that displayed differential expression (upregulation of 206 genes and downregulation of 117 genes), a total of 29 genes (24 upregulated and 5 downregulated genes) were identified as potential candidate genes that may be involved in vasodilation and arterial destiffening. Using real-time quantitative polymerase chain reaction, we confirmed the results of microarray analysis that prostaglandin EP2 receptor (PGE-EP2R), prostaglandin EP4 receptor (PGE-EP4R), C-type natriuretic peptide (CNP), and endothelial nitric oxide synthase (eNOS) genes were differentially expressed. Furthermore, there were modest correlations between arterial stiffness and levels of these factors. Differential expression of eNOS gene was further verified at protein level by using Western blot analysis.

CONCLUSION

These results suggest that exercise training induces the altered expression in several genes including prostaglandin, CNP, and nitric oxide in the aorta and that these molecular changes (particularly eNOS as its protein expression was altered) may contribute, at least in part, to the beneficial effect of exercise training on aortic stiffness.

Tumor necrosis factor-α mediates the proliferation of rat C6 glioma cells via β-adrenergic receptors

In the present study, we observed that isoproterenol, a beta-adrenergic receptor (beta-AR) agonist, stimulated rat C6 glioma cell proliferation, while propranolol, a beta-AR blocker, greatly reduced the proliferative effect of TNF-alpha on C6 cells. The gene and protein expressions of both beta1- and beta2-ARs were enhanced in C6 cells after TNF-alpha treatment, and the increase in beta-AR was due to an increased number of binding sites and not due to increase in receptor affinity. We further showed that protein kinase C (PKC) was involved in the TNF-alpha-induced beta-AR expression. Collectively, our results indicate that TNF-alpha-induced proliferation in C6 glioma cells might be via the induction and activation of beta-ARs.

Normal rat hepatic stellate cells respond to endotoxin in LBP-independent manner to produce inhibitor(s) of DNA synthesis in hepatocytes

Endotoxin is implicated in the pathology of acute liver failure. The mechanisms of its actions on quiescent hepatic stellate cells (qHSCs) and their implications in hepatocyte injury are incompletely understood. We investigated effects of endotoxin (bacterial lipopolysaccharide; LPS) on qHSCs and subsequently on hepatocytes. After overnight culture following their isolation, qHSCs were incubated with or without endotoxin for 24 h. The cells and the culture supernatant were analyzed for cytokines and nitric oxide (NO) synthesis. The effects of qHSC-conditioned media on hepatocytes were then determined. LPS increased inducible NO synthase expression, stimulated NO synthesis, and inhibited DNA synthesis in qHSCs. qHSC-conditioned medium inhibited DNA synthesis in hepatocytes without affecting NO synthesis, while LPS (1-1,000 ng/ml)-conditioned qHSC medium stimulated NO synthesis and caused further inhibition of DNA synthesis and apoptosis. These effects of LPS were more pronounced when qHSCs were incubated with serum, but not with LPS-binding protein (LBP) although CD14 (a receptor for LPS-LBP complex) was found in qHSCs. LPS stimulated the synthesis of TNF-alpha, interleukin (IL)-6, and IL-1beta but not of TGF-beta in qHSCs. Individually or together, L-N(G)-monomethylarginine and antibodies to IL-1beta, IL-6, and TNF-alpha only partly reversed qHSC + LPS-conditioned medium-induced inhibition of DNA synthesis in hepatocytes. These results suggest that the effects of LPS on qHSCs are novel, occurring without the aid of LBP/CD14. They also indicate that other factors, in addition to NO, TGF-beta, TNF-alpha, IL-1beta, and IL-6 are involved in the mechanisms of the growth inhibitory effects of qHSCs on hepatocytes.

Expression of nitric oxide synthase isoforms in hypothalamo–pituitary–adrenal axis during the development of spontaneous hypertension in rats

This study was performed to investigate the expression of the major isoforms of nitric oxide synthase mRNA and protein in the hypothalamo-pituitary-adrenal axis (HPA axis) of spontaneously hypertensive rats (SHR) at two different postnatal ages corresponding to the development of genetic hypertension. Using RT-PCR and Western blot techniques, the mRNA and protein levels of neuronal (nNOS), endothelial (eNOS) and inducible (iNOS) isoforms were measured in 3- to 4-week-old (prehypertensive phase) and 12- to 13-week-old (established hypertension phase) SHR and age-matched normotensive Wistar-Kyoto (WKY) rats. nNOS but not eNOS mRNA levels were increased at prehypertensive and hypertensive phases in SHR HPA axis. Compared to age-matched WKY rats, significantly higher levels of nNOS protein were found in the hypothalamus, lower levels in the adrenal glands and no changes were observed in the pituitary gland. At both ages tested, there was no significant change in eNOS protein expression in SHR HPA axis. The expression of iNOS mRNA and protein was under detection limit. In the HPA axis, the expression of nNOS isoform appears to be differentially controlled at the transcriptional and translational levels in SHR. Increased mRNA levels and differential nNOS protein expression from birth in SHR HPA axis may contribute in the pathogenesis of genetic hypertension.

Characterization of microsomal cytochrome P450-dependent monooxygenases in the rat olfactory mucosa

Nasal administration of a drug ensures therapeutic action by rapid systemic absorption and/or the entry of some molecules into the brain through different routes. Many recent studies have pointed out the presence of xenobiotic-metabolizing enzymes in rat olfactory mucosa (OM). Nevertheless, very little is known about the precise identity of isoforms of cytochrome P450 (P450)-dependent monooxygenases (P450) and their metabolic function in this tissue. Therefore, we evaluated mRNA expression of 19 P450 isoforms by semiquantitative reverse transcriptase-polymerase chain reaction and measured their microsomal activity toward six model substrates. For purposes of comparison, studies were conducted on OM and the liver. Specific activities toward phenacetin, chlorzoxazone, and dextromethorphan are higher in OM than in the liver; those toward lauric acid and testosterone are similar in both tissues, and that toward tolbutamide is much lower in OM. There are considerable differences between the two tissues with regard to mRNA expression of P450 isoforms. Some isoforms are expressed in OM but not in the liver (CYP1A1, 2G1, 2B21, and 4B1), whereas mRNA of others (CYP2C6, 2C11, 2D2, 3A1, 3A2, and 4A1) is present only in hepatic tissue. Although expression of CYP1A2, 2A1, 2A3, 2B2, 2D1, 2D4, 2E1, 2J4, and 3A9 is noticed in both tissues, there are a number of quantitative differences. On the whole, our results strongly suggest that CYP1A1, 1A2, 2A3, 2E1, 2G1, and 3A9 are among the main functional isoforms present in OM, at least regarding activities toward the six tested substrates. The implication of olfactory P450-dependent monooxygenases in toxicology, pharmacology, and physiology should be further investigated.

Clinorotation prevents differentiation of rat myoblastic L6 cells in association with reduced NF-kappa B signaling

In this study, we examined effects of the three-dimensional (3D)-clinorotation, a simulated-model of microgravity, on proliferation/differentiation of rat myoblastic L6 cells. Differentiation of L6 cells into myotubes was significantly disturbed in the 3D-clinorotation culture system, although the 3D-clinorotation had no effect on the proliferation. The 3D-clinorotation also suppressed the expression of myogenesis marker proteins, such as myogenin and myosin heavy chain (MHC), at the mRNA level. In association with this reduced differentiation, we found that the 3D-clinorotation prevented accumulation of ubiquitinated proteins, compared with non-rotation control cells. Based on these findings, we focused on the ubiquitin-dependent degradation of I kappa B, a myogenesis inhibitory protein, to clarify the mechanism of this impaired differentiation. A decline in the amount of I kappa B protein in L6 cells was significantly prevented by the rotation, while the amount of the protein in the non-rotated cells decreased along with the differentiation. Furthermore, the 3D-clinorotation reduced the NF-kappaB-binding activity in L6 cells and prevented the ubiquitination of I kappa B proteins in the I kappa B- and ubiquitin-expressing Cos7 cells. Other myogenic regulatory factors, such as deubiquitinases, cyclin E and oxygen, were not associated with the differentiation impaired by the clinorotation. Our present results suggest that simulated microgravity such as the 3D-clinorotation may disturb skeletal muscle cell differentiation, at least in part, by inhibiting the NF-kappa B pathway.

Mild hypothermia prevents brain edema and attenuates up-regulation of the astrocytic benzodiazepine receptor in experimental acute liver failure

BACKGROUND/AIMS

Mild hypothermia has proven useful in the clinical management of patients with acute liver failure. Acute liver failure in experimental animals results in alterations in the expression of genes coding for astrocytic proteins including the "peripheral-type" (astrocytic) benzodiazepine receptor (PTBR), a mitochondrial complex associated with neurosteroid synthesis. To gain further insight into the mechanisms whereby hypothermia attenuates the neurological complications of acute liver failure, we investigated PTBR expression in the brains of hepatic devascularized rats under normothermic (37 degrees C) and hypothermic (35 degrees C) conditions.

METHODS

PTBR mRNA was measured using semi-quantitative RT-PCR in cerebral cortical extracts and densities of PTBR sites were measured by quantitative receptor autoradiagraphy. Brain pregnenolone content was measured by radioimmunoassay.

RESULTS

At coma stages of encephalopathy, animals with acute liver failure manifested a significant increase of PTBR mRNA levels. Brain pregnenolone content and [(3)H]PK 11195 binding site densities were concomitantly increased. Mild hypothermia prevented brain edema and significantly attenuated the increased receptor expression and pregnenolone content.

CONCLUSIONS

These findings suggest that an attenuation of PTBR up-regulation resulting in the prevention of increased brain neurosteroid content represents one of the mechanisms by which mild hypothermia exerts its protective effects in ALF.

Angiotensin II stimulates Pax-2 in rat kidney proximal tubular cells: impact on proliferation and apoptosis

BACKGROUND

The intrarenal renin-angiotensin system (RAS) is intimately involved in the tubular cell proliferation, apoptosis and regeneration that occur following renal injury. Though tubular angiotensin II (Ang II) type 2 receptors (AT2R) decrease greatly after birth, their number increases after injury. Notably, during recovery from injury, renal tubular cells display a relatively immature phenotype expressing genes that are involved in nephron development, for example, the paired homeobox-2 gene (Pax-2). The present investigation hypothesized that AT2R activation would stimulate Pax-2 gene expression in immortalized rat renal proximal tubular cells (IRPTC), as we have found in fetal cells.

METHODS

Pax-2 gene expression in IRPTC was evaluated by immunofluorescence, Western blot, reverse transcription-polymerase chain reaction (RT-PCR) with or without Ang II treatment; apoptosis and proliferation were analyzed by terminal transferase-mediated deoxyuridine triphosphate (dUTP) nick end-labeling (TUNEL) assay and bromodeoxyuridine (BrdU) incorporation in stable IRPTC transformants with Pax-2 sense and antisense orientation, respectively.

RESULTS

Ang II up-regulated Pax-2 gene expression via AT2R in IRPTC. The stimulatory effect of both Ang II on Pax-2 gene expression was blocked by PD123319 (AT2R inhibitor), AG 490 (specific Janus kinase 2 (JAK2) inhibitor) and genistein (tyrosine kinase inhibitor), but not by losartan (AT1R inhibitor). Stable transfection of sense Pax-2 cDNA increased, whereas antisense Pax-2 cDNA down-regulated Pax-2 expression.

CONCLUSION

Our studies suggest that Ang II stimulates Pax-2 gene expression in IRPTC via AT2R and the JAK2/signal transducers and activators of transcription (STAT) signaling transduction pathway, which may be important in renal repair following injury. Cells lacking Pax-2 gene expression appear to be prone toward apoptosis rather than proliferation.

Manganese superoxide dismutase induced by TNF-beta is regulated transcriptionally by NF-kappaB after spinal cord injury in rats

Antioxidant enzymes including superoxide dismutase (SOD) may play a role in the mechanism by which cells counteract the deleterious effects of reactive oxygen species (ROS) after spinal cord injury (SCI). Cu/Zn and MnSOD are especially potent scavengers of superoxide anion and likely serve important cytoprotective roles against cellular damage. We investigated expression of SOD after SCI to address its role during the early stages of injury. MnSOD activity was increased 4 h after SCI and persisted at elevated levels up to 24-48 h; by contrast, Cu/ZnSOD activity was not changed. RT-PCR and Western blot analyses showed increased levels of MnSOD mRNA and protein, respectively, by 4 h and reached maximum levels by 24-48 h. Double immunostaining revealed that MnSOD protein was localized within neurons and oligodendrocytes. Tumor necrosis factor-alpha (TNF-alpha) was administered locally into uninjured spinal cords to examine potential mechanisms for MnSOD induction after injury. TNF-alpha administered exogenously increased MnSOD expression in uninjured spinal cords. Western blot and immunostaining also revealed that a transcription factor, NF-kappaB, was activated and translocated into the nuclei of neurons and oligodendrocytes. By contrast, administration of neutralizing antibody against TNF-alpha into injured spinal cords attenuated the increase in MnSOD expression and activation of NF-kappaB. Double immunostaining revealed that MnSOD was co-localized with NF-kappaB in neurons and oligodendrocytes after SCI. These results suggest that TNF-alpha may be an inducer of NF-kappaB activation and MnSOD expression after SCI and that MnSOD expression induced by TNF-alpha is likely mediated through activation of NF-kappaB.

Induction of pancreatic trypsin by dietary amino acids in rats: four trypsinogen isozymes and cholecystokinin messenger RNA

We previously demonstrated that feeding a diet containing a high level of amino acid mixture simulating casein (AA) induced an increase in pancreatic protease activities in rats. In the present study, this effect of dietary AA was further characterized with three separate experiments. These experiments (1) examined periodic changes in pancreatic and small intestinal trypsin activities after switching from a 20% (a normal nitrogen level) AA diet to a 60% AA (a high nitrogen level) diet; (2) measured the abundance of mRNA for four trypsinogen isozymes and for intestinal cholecystokinin (CCK) and secretin in rats fed 20% and 60% AA diets for 10 days compared with rats fed 20% and 60% casein diets; and (3) measured the abundance of mRNA for four trypsinogen isozymes after chronic administration of CCK. Trypsin activities were gradually increased in both the pancreas and the small intestinal lumen and reached maximum at 5 days after the switch to the 60% AA diet (Exp. 1). This result is evidence that the increase in the protease activity in the pancreas is due to enhancement of pancreatic trypsin production. In experiment 2, pancreatic trypsinogen isozymes I, II, III, and IV mRNA abundance were evaluated by the Northern blotting method using cDNA probes specific for each isozyme mRNA. Abundance of trypsinogen mRNA without trypsinogen I tended to increase in the rats fed the 60% casein diet but tended to decrease in the rats fed the 60% AA diet compared with the respective normal nitrogen level diet groups without significant difference. CCK mRNA abundance in the jejunal mucosa increased as a result of feeding the 60% casein diet, but not the 60% AA diet. Subcutaneous CCK injections (3.5 nmole/kg body weight/day, twice daily, at 8:30 am and 7:30 pm) for 10 days resulted in increased pancreatic trypsin activity, whereas the changes in mRNA of the four trypsinogen isozymes was similar between the 20% and 60% casein groups but differed between the 20% and 60% AA groups (Exp. 3). These results suggest that CCK is not involved in the induction of pancreatic trypsin that occurs with feeding of a high AA diet and that the mechanism of protease induction by dietary AA is different from that in the case of dietary protein.

Lithium inhibits brown adipocyte differentiation

Lithium impairs the appearance of the characteristic morphology of brown adipocytes and downregulates the expression of marker genes of brown adipocyte differentiation. These effects are dose-dependent and are more pronounced when exposure of preadipocytes to lithium is initiated at early stages of differentiation. Although lithium reduces the expression of genes common to both white and brown adipocytes [fatty acid binding protein aP2 (aP2/FABP) or peroxisome proliferating activated receptor gamma], genes expressed differentially in brown adipocytes, i.e., uncoupling protein 1, PPAR gamma coactivator-1alpha, and peroxisome proliferating activated receptor alpha, are particularly sensitive to lithium treatment-dependent downregulation. Brown adipocytes appear as preferential targets of the inhibitory action of lithium on adipocyte differentiation.

Protein kinases and adherens junction dynamics in the seminiferous epithelium of the rat testis

Earlier studies in multiple epithelia have shown that cell-cell actin-based adherens junction (AJ) dynamics are regulated, at least in part, by the interplay of kinases and phosphatases that determines the intracellular phosphoprotein content. Yet it is virtually unknown regarding the role of protein kinases in Sertoli-germ cell AJ dynamics in the seminiferous epithelium of the testis. To address this issue, an in vitro coculture system utilizing Sertoli and germ cells was used to study the regulation of several protein kinases, including c-Src (the cellular form of the v-src transforming gene of Rous Sarcoma virus, RSV), carboxyl-terminal Src kinase (Csk), and casein kinase 2 (CK2), during AJ assembly. Both Sertoli and germ cells were shown to express c-Src, Csk, and CK2 with a relative Sertoli:germ cell ratio of approximately 1:1, suggesting both cell types contributed equally to the pool of these kinases in the epithelium. c-Src and Csk were shown to be stage-specific proteins during the epithelial cycle, being highest at stages VII-VIII. Studies using immunoprecipitation have illustrated that these kinases were structurally associated with the N-cadherin/beta-catenin, but not the nectin/afadin, protein complex, implicating that the cadherin/catenin protein complex is their likely putative substrate. An induction in c-Src, Csk, and CK2 were detected during Sertoli-germ cell AJ assembly in vitro but not when Sertoli cells were cultured alone. When adult rats were treated with 1-(2,4-dichlorobenzyl)-indazole-3-carbohydrazide (AF-2364), a compound known to induce germ cell loss from the seminiferous epithelium, in particular elongating/elongate and round spermatids, by disrupting Sertoli-germ cell AJs, an induction of c-Src and Csk, but not CK2, was detected. Furthermore, a transient increase in the intrinsic kinase activities of c-Src, but not CK2, was also detected. This event was also associated with a loss of protein-protein association of N-cadherin and beta-catenin from the cadherin/catenin/c-Src/Csk/CK2 protein complex. Administration of PP1, a c-Src inhibitor, into adult rats via the jugular vein could induce the loss of spermatocytes and round spermatids, but not elongating/elongate spermatids, from the seminiferous epithelium. This result thus implicates the importance of c-Src in maintaining the integrity of AJs and possibly desmosome-like junctions between Sertoli cells and spermatocytes/round spermatids. In short, the data reported herein have shown that c-Src, Csk, and CK2 are novel protein kinases in AJ dynamics in the testis.

Ischemic preconditioning of remote organs attenuates gastric ischemia-reperfusion injury through involvement of prostaglandins and sensory nerves

Limitation of the stomach damage by its earlier brief ischemia and reperfusion before prolonged ischemia is defined as gastric ischemic preconditioning but whether such brief ischemia of remote organs like heart or liver can also attenuate the gastric damage caused by longer and severe ischemia-reperfusion remains unknown. The cardiac, hepatic and gastric preconditioning were induced by brief ischemia (occlusion of coronary, hepatic and celiac arteries twice for 5 min) applied 30 min before 3 h of ischemia/reperfusion. Standard 3 h ischemia-reperfusion of the stomach produced numerous gastric lesions, decreased gastric blood flow and mucosal prostaglandin E2 generation and increased expression and plasma release of interleukin-1beta and tumor necrosis factor-alpha (TNF-alpha). These effects were significantly attenuated by brief cardiac, hepatic and gastric preconditioning which upregulated cyclooxygenase-2 mRNA but not cyclooxygenase-1 mRNA. The protective effects of brief gastric, cardiac and hepatic preconditioning were attenuated by selective cyclooxygenase-1 and cyclooxygenase-2 inhibitors and capsaicin denervation. We conclude that brief ischemia of remote preconditioning such as heart or liver protects gastric mucosa against severe ischemia-reperfusion-induced gastric lesions as effectively as local preconditioning of the stomach itself via the mechanism involving prostaglandin derived from cyclooxygenase-1 and cyclooxygenase-2 and the activation of sensory nerves releasing calcitonin gene-related peptide (CGRP) combined with the suppression of interleukin-1beta and TNF-alpha expression and release.

Effects of iridoid total glycoside from Cornus officinalis on prevention of glomerular overexpression of transforming growth factor beta 1 and matrixes in an experimental diabetes model

The present study was conducted to determine whether iridoid total glycoside from Cornus officinalis was effective in regulating expression of transforming growth factor beta 1 (TGF-beta1) and preventing overdeposition of extracellular matrix (ECM) in a diabetes state. An experimental rat model of diabetic nephropathy (DN) was successfully induced by one intraperitoneal injection of streptozotocin at a dose of 60 mg x kg(-1) and maintained for 12 weeks. All rats had free access to standard chow and water. Four groups: normal control, diabetic control, diabetic rats with aminoguanidine treatment and diabetic rats with iridoid total glycoside treatment were used in this experiment. All treatments were administered by intragastric gavage (ig). At the end of the experiment, serum was collected for ELISA determination of TGF-beta1 protein level; renal cortex was dissected for reverse transcription polymerase chain reaction (RT-PCR) analysis of its mRNA expression; and immunohistochemistry was introduced to observe ECM deposition. A significantly higher level of protein and mRNA expression of TGF-beta1, and also overdeposition of fibronectin and laminin was found in diabetic rats. Both iridoid total glycoside and aminoguanidine were effective in decreasing serum protein level and glomerular mRNA expression of TGF-beta1, and in preventing renal overdeposition of fibronectin and laminin. This study suggests that iridoid total glycoside is a beneficial agent for prevention and therapy of DN.

Regulation of CRF, POMC and MC4R gene expression after electrical foot shock stress in the rat amygdala and hypothalamus

We investigated the effects of electrical foot shock stress on the melanocortin signaling cascade and the hypothalamus-pituitary-adrenal (HPA) system by observing levels of mRNA expression of corticotropin releasing factor (CRF), pro-opiomelanocortin (POMC), and melanocortin receptor subtype 4 (MC4R) in the rat amygdala and hypothalamus. When rats were exposed to electrical shock for 0.5 hr or 1 hr, plasma ACTH and corticosterone concentrations increased, indicating stress. The rats were then sacrificed to obtain RNA preparations from the brain tissue. In the amygdala, the expression of MC4R and POMC mRNA as well as CRF mRNA was significantly increased by electrical foot shock stress. In the hypothalamus, MC4R and POMC mRNA increased, but CRF mRNA remained unchanged. The duration of increased gene expression of MC4R and POMC in the amygdala was more sustained than in the hypothalamus. These results have provided the first evidence that exposure to stress increases expression of the MC4R system in the amygdala and hypothalamus.

Heterogenous nuclear ribonucleoprotein F modulates angiotensinogen gene expression in rat kidney proximal tubular cells

An insulin-responsive element (IRE) in the rat angiotensinogen (ANG) gene promoter that binds to two nuclear proteins with apparent molecular weights of 48 and 70 kD was identified previously from rat immortalized renal proximal tubular cells (IRPTC). The present studies aimed to identify and clone the 48-kD nuclear protein and to define its action on ANG gene expression. Nuclear proteins were isolated from IRPTC and subjected to two-dimensional electrophoresis. The 48-kD nuclear protein was detected by Southwestern blotting and subsequently identified by mass spectrometry, revealing that it was identical to 46-kD heterogeneous nuclear ribonucleoprotein F (hnRNP F), a nuclear protein that binds to TATA-binding protein and associates with RNA polymerase II and also interacts with nuclear cap-binding complex. The hnRNP F cDNA was cloned from IRPTC by reverse transcriptase-PCR. Bacterially expressed recombinant hnRNP F bound to the rat ANG-IRE, as revealed by gel mobility shift assay. The addition of polyclonal antibodies against hnRNP F yielded a supershift in gel mobility. Transient transfer of sense and antisense hnRNP F cDNA in IRPTC inhibited and enhanced ANG gene expression, respectively. High glucose stimulated and insulin inhibited hnRNP F expression in IRPTC. Expression studies indicated that hnRNP F is present in the kidney, testis, liver, lung, and brain but not in the spleen. In conclusion, these studies demonstrate that hnRNP F binds to rANG-IRE and modulates renal ANG gene expression, implicating that dysregulation of hnRNP F might affect renin-angiotensin system activation and, subsequently, kidney injury in diabetes.

Microdialysis for measurement of hepatic and systemic nitric oxide biosynthesis in septic rats

BACKGROUND

We sought to compare two techniques, microdialysis and repeated blood withdrawal, for serial assessment of hepatic and systemic nitric oxide (NO) biosynthesis in septic rats.

METHODS

Rats were randomly allocated to either microdialysis or blood withdrawal groups. Two microdialysis probes, one in liver and the other in right atrium, were placed in rats in the microdialysis group. Half of the rats from each group were then given lipopolysaccharide (LPS) to induce NO production. The other half of the rats from each group were injected with vehicle (normal saline) to serve as controls. In the microdialysis group, dialysate (30 microl) was collected every 30 min. In the blood withdrawal group, 0.3 ml of blood was drawn every 30 min. Sampling was performed up to 6 h after injection of LPS or vehicle. Hemodynamics, hepatic and systemic NO concentrations, and iNOS expression in harvested liver tissues were assayed.

RESULTS

Repeated blood withdrawal by itself caused a significant decrease in blood pressure and induced hepatic iNOS expression. Microdialysis, on the contrary, reliably detected LPS-induced NO production without resulting either in hemodynamic changes or in iNOS induction in liver tissue.

CONCLUSIONS

Microdialysis provides serial measure of hepatic and systemic NO concentrations in LPS-treated rats without the need for removal of tissue.

Localization of 5α-reductase in the rat main olfactory bulb

The enzyme steroid 5alpha-reductase catalyzes the production of dihydroprogesterone and dihydrotestosterone, which were recently recognized as neurosteroids in the brain with variably potential neuroactivity. The present study reports for the first time detailed localization of 5alpha-reductase type 1 in the rat main olfactory bulb. The occurrence of 5alpha-reductase in the olfactory bulb was detected by reverse transcription-polymerase chain reaction and Western blotting analyses. In addition, the enzyme activity was also detected by thin layer chromatography. Immunocytochemistry showed that 5alpha-reductase immunoreactive cells of variable intensity were present in all layers of the olfactory bulb. Multiple immunolabeling revealed that 5alpha-reductase was mainly localized in glial cells, namely, in S-100beta- and glial fibrillary acidic protein-immunoreactive astrocytes, 2', 3'-cyclic nucleotide 3'-phosphodiesterase (CNPase)-immunoreactive oligodendrocytes, and in S-100beta- and neuropeptide-Y-immunoreactive olfactory ensheathing cells, whereas the bulbar neurons exhibited little immunoreactivity. Quantitative analysis revealed that the number of 5alpha-reductase-immunoreactive cells was greatest in the olfactory nerve layer. The most intense 5alpha-reductase-immunoreactivity was found in the olfactory ensheathing cells, and next in the CNPase-immunoreactive cells. The 5alpha-reductase in the olfactory bulb was expressed constantly throughout different ages and sexes and in neutered and hypophysectomized rats. Thus, 5alpha-reductase may contribute via 5alpha-reduced metabolites to the formation and maintenance of olfactory inputs and outputs, which were closely associated with the olfactory ensheathing cells and the oligodendrocytes, respectively.

Effect of heat exposure on uncoupling protein-3 mRNA abundance in porcine skeletal muscle

Exposure to cold increases abundance of mRNA for uncoupling protein-3 (UCP3) in skeletal muscle, whereas the influence of exposure to heat is unknown. Thus, we conducted a study to investigate the influence of heat exposure on UCP3 mRNA abundance in porcine skeletal muscle. Three pigs aged 110 to 120 d, with an average BW of 75 kg, from each of eight litters were used. Each littermate was assigned to one of three treatment groups; one group was reared at 32 degrees C and fed ad libitum (32AL) for 4 wk, whereas the other two groups were maintained at 23 degrees C for the same period, and either pair-fed the intake of their 32AL littermates (23PF), or fed ad libitum (23AL). The RNase protection assay revealed that UCP3 mRNA abundance in longissimus dorsi and rhomboideus muscles was higher (P < 0.05) in the 32AL group than the 23PF group. The 23AL group also had significantly higher UCP3 mRNA abundance than the 23PF group in these muscles. Plasma total 3,5,3'-triiodothyronine concentration of the 32AL group was lower (P < 0.05) than that of the 23PF group, whereas mRNA abundance of thyroid hormone receptor (TR) isoforms, TRalpha1 and TRalpha2, in these muscles was not affected, suggesting that the 32AL group was in a relatively hypo-thyroid state. Because thyroid hormone up-regulates UCP3 expression, these results indicate that factors other than thyroid hormone may play a role in regulating UCP3 mRNA abundance in skeletal muscle of heat-exposed pigs.

Pulmonary transcription of CAT-2 and CAT-2B but not CAT-1 and CAT-2A were upregulated in hemorrhagic shock rats

Hemorrhagic shock stimulates nitric oxide (NO) biosynthesis through upregulation of inducible NO synthase (iNOS) expression. Trans-membrane l-arginine transportation mediated by the isozymes of cationic amino acid transporters (e.g. CAT-1, CAT-2, CAT-2A, and CAT-2B) is one crucial regulatory mechanism that regulates iNOS activity. We sought to assess the effects of hemorrhage and resuscitation on the expression of these regulatory enzymes in hemorrhage-stimulated rat lungs. Twenty-four rats were randomized to a sham-instrumented group, a sustained shock group, a shock with blood resuscitation group, or a shock with normal saline resuscitation group. Hemorrhagic shock was induced by withdrawing blood to maintain MAP between 40 and 45mmHg for 60min. Resuscitation by infusing blood/saline mixtures (blood resuscitation group) or saline alone (saline resuscitation group) was then performed. At the end of the experiment (300min after hemorrhage began), rats were sacrificed and enzymes expression as well as pulmonary NO biosynthesis and lung injuries were assayed. Our data revealed that hemorrhage-induced pulmonary iNOS, CAT-2, and CAT-2B transcription which was associated with pulmonary NO overproduction and subsequent lung injury. Resuscitation significantly attenuated the hemorrhage-induced enzyme upregulation, pulmonary NO overproduction, and lung injury. Blood/saline mixtures were superior to saline as a resuscitation solution in treating hemorrhage-induced pulmonary NO overproduction and lung injury. Hemorrhage and/or resuscitation, however, did not affect the expression of pulmonary CAT-1 and CAT-2A. It is, therefore, concluded that the expression of pulmonary iNOS, CAT-2, and CAT-2B is inducible and that of CAT-1 and CAT-2A is constitutive in hemorrhagic shock rat lungs.

Effects of scrotal heating on sperm surface protein PH-20 expression in sheep

Sperm surface protein PH-20 expression was studied during spermatogenesis in pubertal and adult sheep, using molecular and histological methods. The effects of 24 hr of insulation raising scrotal temperatures to 39 degrees C on PH-20 expression in ejaculated sheep sperm were also determined. A 282 nt cDNA fragment of ovine PH-20 was identified in total RNA extracts of sheep testes, which exhibited 76% identity at the nucleotide level with the equivalent region of the human sequence. Ovine PH-20 mRNA and immunoreactivity were identified only in adult ram testis and not in peri-pubertal ram testis tubules lacking round spermatids, nor in adult sheep brain, pituitary, heart, spleen, lung, liver, kidney, epididymis, or ovary. Ovine PH-20 protein was distributed predominantly on the postacrosomal membrane and was also present on the anterior membrane of the sperm head in fresh, unheated sheep semen. Scrotal heating caused a significant, transient decrease in the percentage of PH-20 immunoreactive sperm, but did not change the pattern of PH-20 staining on the sperm head. The results strongly suggest that ovine PH-20 is postmeiotically expressed in haploid germ cells in sheep testis and is arrayed on the membrane of the mature ovine spermatozoon. Scrotal heating appears to have few effects on PH-20 expression and distribution on ejaculated sperm.

Periovulatory Expression of Intercellular Adhesion Molecule-1 in the Rat Ovary1

Leukocytes, especially neutrophils and macrophages, traditional cellular regulators of the immune system, reside within the tissue architecture of the rodent and human ovary and dramatically increase in number, in response to gonadotropin, in the theca of preovulatory follicles. Evidence strongly suggests a modulatory role for leukocytes in ovarian tissue remodeling events, such as ovulation, luteinization, and luteolysis. The present study investigates the ovarian localization and potential gonadotropin regulation of intercellular adhesion molecule-1 (ICAM-1), an important factor in neutrophil and monocyte attachment to endothelium. Reverse transcription-polymerase chain reaction and immunohistochemical detection and quantification of ICAM-1 mRNA and protein were carried out in ovaries of immature and eCG/hCG-primed rats during the periovulatory period (0, 6, 12, and 24 h post-hCG). While whole ovarian ICAM-1 mRNA levels did not vary significantly during the preovulatory period, ovarian follicles exhibited ICAM-1 mRNA and protein specifically within the thecal region, where mRNA expression increased 5-fold and protein expression increased 6-fold when comparing pre-hCG levels with those at the estimated time of ovulation (12 h post-hCG). Thecal ICAM-1 was most prevalent in highly vascularized regions as evidenced by serial staining with an endothelium-specific antibody. Granulosa layer ICAM-1 immunoactivity was acquired only during/after follicle rupture. These results show ICAM-1 is localized within the ovarian theca and its expression is associated with follicular development in periovulatory follicles, peaking in expression at the time of rupture. Additionally, ICAM-1 is expressed among granulosa-lutein cells of the ovulating follicle and developing corpus luteum. Taken together, these findings suggest rat ovarian ICAM-1 may be instrumental in the active recruitment of leukocytes into the preovulatory ovary and may have a role in corpus luteum formation.