Effect of 28-homobrassinolide treatment on nickel toxicity in <Emphasis Type="Italic">Brassica juncea</Emphasis>

Plants of Brassica juncea L. cv. T-59 were supplied with 50 or 100 μM nickel (Ni₅₀, Ni₁₀₀) at 10 d after sowing (DAS), and sprayed with 28-homobrassinolide (HBR) at 20 DAS. The plants treated with Ni alone exhibited reduced growth, net photosynthetic rate, content of chlorophyll, and the activities of nitrate reductase (E.C.1.6.6.1) and carbonic anhydrase (E.C. 4.2.1.1) at observed 40 DAS, whereas, the contents of peroxidase (PER), catalase (CAT), and proline were increased. However, the spray of HBR partially neutralized the toxic effect of Ni on most of the parameters. Moreover, the treatment of HBR in association with either of the Ni concentration boosted the contents of PER and CAT in leaves and that of proline both in leaves and roots.     

Photosynthetic Response of Vigna radiata to Pre-Sowing Seed Treatment with 28-Homobrassinolide

Surface sterilised seeds of mungbean (Vigna radiata L. Wilczek cv. T-44) were soaked in 0, 10⁻⁸, 10⁻⁶, or 10⁻⁴ M aqueous solution of 28-homobrassinolide (HBR) for 4, 8, or 12 h. The treated seeds were grown in sandy loam soil filled in earthen pots and sampled at 30, 40, and 50 d. Net photosynthetic rate, leaf chlorophyll content, carbonic anhydrase activity (E.C. 4.2.1.1), carboxylation efficiency, stomatal conductance, and seed yield at harvest were enhanced by the HBR treatment. The best combination was the pre-sowing seed treatment with 10⁻⁶ M HBR for 8 h. This revised version was published online in August 2006 with corrections to the Cover Date.     

28-Homobrassinolide ameliorates the saline stress in chickpea (Cicer arietinum L.)

The response of chickpea (Cicer arietinum L.) cv. KPG-59 to pre-sowing seed treatment with 28-homobrassinolide (HBR) and/or sodium chloride (NaCl) was investigated. The seeds imbibed in aqueous solution of 10⁻¹⁰ or 10⁻⁸ M of HBR for 8 h, resulted in an increase in the values for most of the characteristics of shoot and root at 90-day stage and seed yield, at harvest. The plants resulting from the seeds soaked in HBR (10⁻⁸ M) possessed 23% and 31% higher leaf nitrate reductase (E.C. 1.6.6.1) and carbonic anhydrase (E.C. 4.2.2.1) activities, 34% more dry mass, 30% higher nodule number, 31% and 18% more nodule fresh and dry mass, compared with water soaked, control. Leghaemoglobin content and nitrogenase activity (E.C. 1.7.99.2) were 28% and 30% higher while nodule nitrogen and carbohydrate contents decreased by 5% and 6%, compared with the control. Moreover, seed yield increased by 26% over the control, at harvest. The values for all the above characteristics declined significantly, in the plants raised from the seeds soaked in NaCl. However, this ill effect was overcome, if NaCl treatment was given before or after HBR treatment.     

In vitro effect of cortisol and urotensin I on arginine vasotocin and isotocin secretion from pituitary cells of gilthead sea bream Sparus aurata

This study aimed at determining whether in vitro secretion of two neuropeptides, arginine vasotocin (AVT) and isotocin (IT), from pituitary cells of gilthead sea bream Sparus aurata was affected by cortisol and urotensin (UI). Pituitary cells were exposed to 1·4 × 10^?8, 1·4 × 10^?7 and 0·4 × 10^?6 M cortisol and 10^?12, 10^?10 and 10^?8 M UI for 6, 24 and 48 h, respectively. AVT and IT contents were determined in the culture media by high‐performance liquid chromatography (HPLC). An increase in AVT secretion and a decrease in IT secretion were observed at all cortisol doses. UI increased AVT secretion after 6 h of incubation at all doses. After 24 h, however, only the highest dose of UI still displayed an effect. IT secretion was not influenced by UI. It was thus demonstrated that cortisol does influence AVT and IT secretion from S. aurata pituitary cells, while UI regulates AVT secretion, as a component of hypothalamic–pituitary–interrenal (HPI) axis in this species.     

Photosynthetic Rate, Growth, and Yield of Mustard Plants Sprayed with 28-Homobrassinolide

Thirty-day-old plants of mustard (Brassica juncea L.) were sprayed with 10⁻¹⁰, 10⁻⁸, or 10⁻⁶ M aqueous solution of 28-homobrassinolide (HBR). The HBR-treated plants were healthier than those treated with water and yielded more. Maximum increase over control was found in 60-d-old, 10⁻⁸ M-HBR-treated plants in fresh and dry mass per plant, carbonic anhydrase (CA, E.C. 4.2.1.1) activity, and net photosynthetic rate (P _N), at harvest in number of pods per plant and seed yield per plant (the respective values were 25, 30, 34, 69, 24, and 29 %). A further increase in the concentration of HBR (10⁻⁶ M) did not make any additional impact on the growth and yield. Increased CA activity and P _N were correlated with growth and seed yield. This revised version was published online in August 2006 with corrections to the Cover Date.     

Carbonic Anhydrase,Photosynthesis, and Seed Yield in Mustard Plants Treated with Phytohormones

The leaves of 30-d-old plants of Brassica juncea Czern & Coss cv. Varuna were sprayed with 10^–6 M aqueous solutions of indole-3-yl-acetic acid (IAA), gibberellic acid (GA₃), kinetin (KIN), and abscisic acid (ABA) or 10^–8 M of 28-homobrassinolide (HBR). All the phytohormones, except ABA, improved the vegetative growth and seed yield at harvest, compared with those sprayed with deionised water (control). HBR was most prominent in its effect, generating 32, 30, 36, 70, 25, and 29 % higher values for dry mass, chlorophyll content, carbonic anhydrase (E.C. 4.2.1.1) activity, and net photosynthetic rate in 60-d-old plants, pods per plant, and seed yield at harvest, over the control, respectively. The order of response to various hormones was HBR > GA₃ > IAA > KIN > control > ABA.     

Kinetics of glucose stimulatory effect on silica deposition and growth of natural populations of Fragilaria crotonensis

Diatoms are known to exploit organic substrates for growth; however, convincing evidence that they can utilize dissolved organic carbon under natural conditions is not available. In 2008–2009, we performed in situ experiments examining the effect of glucose addition on silica deposition kinetics and growth rates of Fragilaria crotonensis in the eutrophic ?ímov Reservoir (Czech Republic). Silica deposition kinetics was measured at 4‐h intervals over a 24‐h incubation with PDMPO [2‐(4‐pyridyl)‐5{[4‐dimethylaminoethyl‐aminocarbamyl)‐methoxy] phenyl}oxazole] fluorescence probe. A significant stimulatory effect of glucose supplemented at the concentration of 10^?4 M on Fragilaria silification was observed at 20 and 24 h. Fragilaria growth rates almost doubled upon glucose enrichment compared with the untreated control at 24 h. In addition, we conducted a dose‐response experiment testing the glucose additions from 10^?8 to 10^?3 M in a 24‐h incubation. Glucose stimulated both Fragilaria silification and growth at concentrations >10^–7 M, which might occasionally occur in a reservoir as a result of accidental contamination of water by organic pollution.     

Involvement of β1‐integrin via PIP complex and FAK/paxillin in dexamethasone‐induced human mesenchymal stem cells migration

Although glucocorticoids strongly affect numerous biological processes including cell growth, development, and homeostasis, their effects on migration of human mesenchymal stem cells (hMSCs) are unclear. Therefore, we investigated the role of dexamethasone (DEX) and its related signaling pathways on migration of hMSCs. We found that DEX, at 10^?8 to 10^?6 M, significantly increased migration after a 24 h incubation, and DEX (10^?6 M) increased migration at >12 h. Moreover, DEX (10^?6 M) increased the level of glucocorticoid receptor (GR)‐α mRNA and protein expression, but not GR‐β mRNA. The increases in DEX‐induced migration were inhibited by the GR antagonist mifepristone (10^?7 M). In addition, DEX increased integrin‐linked kinase (ILK) and α‐parvin expression but did not change PINCH‐1/2 expression in lysate. DEX also increased formations of complex with ILK and α‐parvin, and ILK and PINCH‐1/2 as shown by immunoprecipitation, which were all inhibited by mifepristone. DEX‐induced migration was blocked by ILK and α‐parvin small interfering(si)RNAs. In addition, DEX increased focal adhesion kinase (FAK) and paxillin expression, which were attenuated by ILK and α‐parvin siRNAs. DEX‐induced cell migration was inhibited by FAK/paxillin siRNAs. DEX also increased β1‐integrin expression, which was blocked by FAK/paxillin siRNAs. In addition, DEX‐induced cell migration was inhibited by β1‐integrin siRNA. Downregulation of ILK, α‐parvin, FAK/paxillin and β1‐integrin expression by siRNAs decreased DEX‐induced filamentous(F)‐actin organization and migration of hMSCs. In conclusion, DEX partially stimulates hMSC migration by the expression of β1‐integrin through formation of a PINCH‐1/2/ILK/α‐parvin complex (PIP complex), and FAK and paxillin expression. J. Cell. Physiol. 226: 683–692, 2011. © 2010 Wiley‐Liss, Inc.     

In vitro effects of 2‐methoxyestradiol on cell numbers,morphology, cell cycle progression,and apoptosis induction in oesophageal carcinoma cells

The influence of 2‐methoxyestradiol (2‐ME) was investigated on cell numbers, morphology, cell cycle progression, and apoptosis induction in an oesophageal carcinoma cell line (WHCO3). Dose‐dependent studies (1 × 10^?9M–1 × 10^?6M) revealed that 2‐ME significantly reduced cell numbers to 60% in WHCO3 after 72 h of exposure at a concentration of 1 × 10^?6M compared to vehicle‐treated cells. Morphological studies entailing light‐, fluorescent‐, as well as transmission electron microscopy (TEM) confirmed 2‐ME's antimitotic effects. These results indicated hallmarks of apoptosis including cell shrinkage, hypercondensation of chromatin, cell membrane blebbing, and apoptotic bodies in treated cells. Flow cytometric analyses demonstrated an increase in the G₂/M‐phase after 2‐ME exposure; thus preventing cells from proceeding through the cell cycle. β‐tubulin immunofluorescence revealed that 2‐ME caused spindle disruption. In addition, increased expression of death receptor 5 protein was observed further supporting the proposed mechanism of apoptosis induction via the extrinsic pathway in 2‐ME‐exposed oesophageal carcinoma cells. Copyright © 2009 John Wiley & Sons, Ltd.     

A comparative effect of IAA and 4-Cl-IAA on growth,nodulation and nitrogen fixation in <Emphasis Type="Italic">Vigna radiata</Emphasis> (L.) Wilczek

The plants of mung bean (Vigna radiata L. Wilczek) were raised from the seeds soaked in water (control), IAA or 4-C-IAA (10⁻⁶, 10⁻⁸ or 10⁻¹⁰ M) for 8 or 12 h. The plants were allowed to grow in a net house and were sampled at 30 and 45 days after sowing (DAS). Both IAA and 4-Cl-IAA significantly affected the growth (length, fresh and dry mass of roots and shoots), the number of nodules, their fresh and dry mass and the activity of nitrogenase. However, the contents of nitrogen and carbohydrate exhibited a decrease in response to both the auxins. 4-Cl-IAA, at a concentration of 10⁻⁸ M, generated the best response. Moreover, 4-Cl-IAA at other two concentrations (10⁻⁶ and 10⁻¹⁰ M) was much more active than any of the IAA concentration used.     

The influence of vasoactive intestinal polypeptide and cholecystokinin of prolactin release in rat and human monolayer cultures

We have evaluated the effects of the gut-brain peptides, VIP and CCK, on pituitary PRL secretion in monolayer cultures of normal and tumor bearing rodent and human pituitary tissue. In cultures prepared with normal human pituitary tissue obtained from three patients with metastatic breast cancer, VIP at 10^?7M and 10^?9M (but not 10^?11M) significantly (p<.05) increased PRL secretion in the wells by 6 hrs. Similar concentrations of VIP also significantly (p<.05) promoted PRL release from pituitary tissue obtained by transphenoidal hypophysectomy from one of two prolactinoma patients. Dopamine (10^?5M) inhibition of PRL secretion was not affected by 10^?11 to 10^?7M VIP. In contrast to these findings VIP did not significantly influence 6 hr rat PRL release in monolayer cultures of normal or transformed cells (GH₃) with or without the addition of bacitracin (10^?5M).CCK₃₃ significantly (p<.01) increased rat PRL release in human pituitary monolayer cultures at 10^?5M. The more biologically potent CCK₈ significantly (p<.02) increased rat PRL release at a 10-fold lower concentration, 10^?6M. In contrast, CCK₈ 10^?8 to 10^?6M, did not significantly influence PRL release from normal human pituitary cultures or from tumor bearing human (prolactinoma) and rat (GH₃) cultures. We conclude that 1) the gut-brain peptides, VIP and CCK, can directly stimulate pituitary PRL release and 2) VIP may be a physiologic prolactin releasing factor in man.     

Chondro/osteoblastic and cardiovascular gene modulation in human artery smooth muscle cells that calcify in the presence of phosphate and calcitriol or paricalcitol

Vitamin D sterol administration, a traditional treatment for secondary hyperparathyroidism, may increase serum calcium and phosphorus, and has been associated with increased vascular calcification (VC). In vitro studies suggest that in the presence of uremic concentrations of phosphorus, vitamin D sterols regulate gene expression associated with trans‐differentiation of smooth muscle cells (SMCs) to a chondro/osteoblastic cell type. This study examined effects of vitamin D sterols on gene expression profiles associated with phosphate‐enhanced human coronary artery SMC (CASMC) calcification. Cultured CASMCs were exposed to phosphate‐containing differentiation medium (DM) with and without calcitriol, paricalcitol, or the calcimimetic R‐568 (10^?11–10^?7 M) for 7 days. Calcification of CASMCs, determined using colorimetry following acid extraction, was dose dependently increased (1.6‐ to 1.9‐fold) by vitamin D sterols + DM. In contrast, R‐568 did not increase calcification. Microarray analysis demonstrated that, compared with DM, calcitriol (10^?8 M) + DM or paricalcitol (10^?8 M) + DM similarly and significantly (P < 0.05) regulated genes of various pathways including: metabolism, CYP24A1; mineralization, ENPP1; apoptosis, GIP3; osteo/chondrogenesis, OPG, TGFB2, Dkk1, BMP4, BMP6; cardiovascular, HGF, DSP1, TNC; cell cycle, MAPK13; and ion channels, SLC22A3 KCNK3. R‐568 had no effect on CASMC gene expression. Thus, SMC calcification observed in response to vitamin D sterol + DM may be partially mediated through targeting mineralization, apoptotic, osteo/chondrocytic, and cardiovascular pathway genes, although some gene changes may protect against calcification. Further studies to determine precise roles of these genes in development of, or protection against VC and cardiovascular disease are required. J. Cell. Biochem. 111: 911–921, 2010. © 2010 Wiley‐Liss, Inc.     

Three‐dimensional (3‐D) fluorescence spectroscopy analysis of the fluorescent dissolved organic matter released by the marine toxic dinoflagellate Alexandrium catenella exposed to metal stress by zinc or lead

We investigated the effects of zinc or lead on growth and on exudation of fluorescent dissolved organic matter (FDOM) by the marine toxic dinoflagellate Alexandrium catenella (Whedon & Kofoid) Balech. The species was exposed to increasing free zinc (1.34 × 10^?7 M–3.98 × 10^?6 M) or lead (5.13 × 10^?9 M–1.82 × 10^?7 M) concentra‐tions. Low metal levels ([Zn²⁺] = 1.34 × 10^?7 M; [Pb²⁺] = 5.13 × 10^?9 M) had no effect on cell growth. Toxic effects were observed from higher metal contamination ([Zn²⁺] = 3.98 × 10^?6 M; [Pb²⁺] = 6.54 × 10^?8 M), as a conversion of vegetative cells into cysts. Analysis of the released FDOM by three‐dimensional (3‐D) fluorescence spectroscopy was achieved, using the parallel factor analysis (PARAFAC). The PARAFAC modeling revealed four components associated with two contributions: one related to the biological activity; the other linked to the organic matter decomposition in the culture medium. The C1 component combined a tryptophan peak and characteristics of humic substances, whereas the C2 component was considered as a tryptophan protein fluorophore. The two others C3 and C4 components were associated with marine organic matter production. Relea‐sed fluorescent substances were induced by low ([Zn²⁺]= 1.34 × 10^?7 M; [Pb²⁺] = 5.13 × 10^?9 M) and moderate ([Zn²⁺] = 6.21 × 10^?7 M; [Pb²⁺] = 2.64× 10^?9 M) metal concentrations, suggesting the activation of cellular mechanisms in response to metal stress, to exudate FDOM that could complex metal cations and reduce their toxicity toward A. catenella cells.     

High glucose regulates cyclin D1/E of human mesenchymal stem cells through TGF‐β1 expression via Ca2+/PKC/MAPKs and PI3K/Akt/mTOR signal pathways

The elucidation of factors that support human mesenchymal stem cells (hMSCs) growth has remained unresolved partly because of the reliance of many researchers on ill‐defined, proprietary medium formulation. Thus, we investigated the effects of high glucose (D ‐glucose, 25 mM) on hMSCs proliferation. High glucose significantly increased [³H]‐thymidine incorporation and cell‐cycle regulatory protein expression levels compared with 5 mM D ‐glucose or 25 mM L ‐glucose. In addition, high glucose increased transforming growth factor‐β1 (TGF‐β₁) mRNA and protein expression levels. High glucose‐induced cell‐cycle regulatory protein expression levels and [³H]‐thymidine incorporation, which were inhibited by TGF‐β₁ siRNA transfection and TGF‐β₁ neutralizing antibody treatment. High glucose‐induced phosphorylation of protein kinase C (PKC), p44/42 mitogen‐activated protein kinases (MAPKs), p38 MAPK, Akt, and mammalian target of rapamycin (mTOR) in a time‐dependent manner. Pretreatment of PKC inhibitors (staurosporine, 10^?6 M; bisindolylmaleimide I, 10^?6 M), LY 294002 (PI3 kinase inhibitor, 10^?6 M), Akt inhibitor (10^?5 M), PD 98059 (p44/42 MAPKs inhibitor, 10^?5 M), SB 203580 (p38 MAPK inhibitor, 10^?6 M), and rapamycin (mTOR inhibitor, 10^?8 M) blocked the high glucose‐induced cellular proliferation and TGF‐β₁ protein expression. In conclusion, high glucose stimulated hMSCs proliferation through TGF‐β₁ expression via Ca²⁺/PKC/MAPKs as well as PI3K/Akt/mTOR signal pathways. J. Cell. Physiol. 224:59–70, 2010 © 2010 Wiley‐Liss, Inc.     

Measurement of blood volume in the elasmobranch fish Scyliorhinus canicula following acute and long‐term salinity transfers

A technique using ⁵¹chromium‐labelled erythrocytes was used to measure blood volume in Scyliorhinus canicula following long‐term and acute salinity transfers. Basal whole‐blood volume was 5·6 ± 0·2 ml 100 g^?1 (mean ±s .e .), this increased (6·3 ± 0·2 ml 100 g^?1) following +14 day acclimation to 80% sea water (SW) and decreased (4·6 ± 0·2 ml 100 g^?1) following acclimation to 120% SW. These changes were shown to be primarily due to changes in plasma volume, with no significant changes in extrapolated red‐cell volume being demonstrated. Blood volume was also measured in the same animals during 10 h acute transfer to 100% SW. Plasma volume in S. canicula during acclimation from 80% SW was significantly reduced (4·5 ± 0·3 ml 100 g^?1) after 6 h of transfer to 100% SW. Blood volume in animals during acclimation from 120% SW was significantly increased (4·8 ± 0·2 ml 100 g^?1) after 4 h of acute transfer. The osmoregulatory implications of these different timeframes during hyposaline and hypersaline transfer are discussed, along with the importance of this in vivo technique as context for in vitro studies with haemo‐dynamic stimuli.     

Growth of tomato (Lycopersicon esculentum) in response to salicylic acid under water stress

Abstract

Plants of Lycopersicon esculentum L. cv. K-25 were subjected to water stress by withholding water for 10 days at 20 (WS I) and 30 (WS II) days after sowing (DAS). Seedlings were sprayed with double distilled water (DDW) or 10^?5M salicylic acid (SA) at 45 DAS. The water stress at earlier stage of growth (20 day stage) was more inhibitory as compared to the later stage (30 day stage). The plants exposed to water stress exhibited a significant (p<0.05) decline in photosynthetic parameters, membrane stability index (MSI), leaf water potential, activity of nitrate reductase (NR), carbonic anhydrase (CA), chlorophyll and relative water content (RWC). A follow-up treatment with SA protected against the stress generated by water and significantly improved the above parameters. However, proline content and antioxidant enzymes increased under drought as well as under SA treatments.     

Fine root dynamics in a loblolly pine forest are influenced by free-air-CO2-enrichment: a six-year-minirhizotron study

Efforts to characterize carbon (C) cycling among atmosphere, forest canopy, and soil C pools are hindered by poorly quantified fine root dynamics. We characterized the influence of free‐air‐CO₂‐enrichment (ambient +200 ppm) on fine roots for a period of 6 years (Autumn 1998 through Autumn 2004) in an 18‐year‐old loblolly pine (Pinus taeda) plantation near Durham, NC, USA using minirhizotrons. Root production and mortality were synchronous processes that peaked most years during spring and early summer. Seasonality of fine root production and mortality was not influenced by atmospheric CO₂ availability. Averaged over all 6 years of the study, CO₂ enrichment increased average fine root standing crop (+23%), annual root length production (+25%), and annual root length mortality (+36%). Larger increase in mortality compared with production with CO₂ enrichment is explained by shorter average fine root lifespans in elevated plots (500 days) compared with controls (574 days). The effects of CO₂‐enrichment on fine root proliferation tended to shift from shallow (0–15 cm) to deeper soil depths (15–30) with increasing duration of the study. Diameters of fine roots were initially increased by CO₂‐enrichment but this effect diminished over time. Averaged over 6 years, annual fine root NPP was estimated to be 163 g dw m^?2 yr^?1 in CO₂‐enriched plots and 130 g dw m^?2 yr^?1 in control plots (P= 0.13) corresponding to an average annual additional input of fine root biomass to soil of 33 g m^?2 yr^?1 in CO₂‐enriched plots. A lack of consistent CO₂× year effects suggest that the positive effects of CO₂ enrichment on fine root growth persisted 6 years following minirhizotron tube installation (8 years following initiation of the CO₂ fumigation). Although CO₂‐enrichment contributed to extra flow of C into soil in this experiment, the magnitude of the effect was small suggesting only modest potential for fine root processes to directly contribute to soil C storage in south‐eastern pine forests.     

Effects of human chorionic gonadotropin (hCG) and handling stress on spermiation of silver perch Leiopotherapon plumbeus (Kner, 1864)

This study determined the effect of human chorionic gonadotropin (hCG) and handling stress on the spermiation and milt response of silver perch Leiopotherapon plumbeus based on the measurement of spermatocrit, sperm density, and milt production. Compared to saline‐injected fish, the mean spermatocrit (or packed sperm) of hCG‐treated fish was significantly lower at 18 h (47.9%) and 30 h (40.2%) post‐injection while mean sperm density was significantly lower at 30 h post‐injection (3.6 × 10⁶ cells μl^?1) but not at 18 h. At 18 h (1.8 μl g‐BW^?1) and 30 h (2.5 μl g‐BW^?1) post‐injection, mean milt production of hCG‐treated fish was significantly higher than in the saline group. Milt consistency was also thinner in the hCG‐treated group. Mean sperm density of handled fish (18.0 × 10⁶ cells μl^?1) was significantly lower than control fish (23.4 × 10⁶ cells μl^?1). However, mean sperm density of handled plus saline‐injected (16.2 × 10⁶ cells μl^?1) and handled plus hCG‐treated fish (8.4 × 10⁶ cells μl^?1) was significantly lower than in the control goup. Having thicker milt consistency, mean spermatocrit and milt production of handled (77.5%; 1.1 μl g‐BW^?1, respectively) and handled plus saline‐injected fish (75.4%; 1.1 μl g‐BW^?1, respectively) were not significantly different from the control fish (76.2%; 1.3 μl g‐BW^?1, respectively). Handled plus hCG‐treated fish had the lowest mean sperm density (8.4 × 10⁶ cells μl^?1) and spermatocrit (54.7%), but had the highest mean milt production (5.5 μl g‐BW^?1) among the treatment groups. These results demonstrate that the hCG injection effectively induces spermiation and milt expression and that handling‐related stress negatively affects such responses. The spermatocrit method may be used to assess the spermiation and milt response of silver perch.     

Circulating IL-6 concentrations and abdominal adipocyte isoproterenol-stimulated lipolysis in women

Objective: To examine the association of plasma interleukin‐6 (IL‐6) concentrations with adiposity and fat cell metabolism in women. Methods and Procedures: Omental (OM) and subcutaneous (SC) adipose tissue samples were obtained from 48 healthy women (age: 47 ± 5 years, BMI: 26.9 ± 5.3 kg/m²) undergoing gynecological surgeries. Total and visceral adiposity were assessed by dual‐energy X‐ray absorptiometry and computed tomography, respectively. Measures of adipocyte lipolysis (basal, isoproterenol‐, forskolin‐, and cyclic dibutyryl‐adenosine monophosphate (AMP)‐stimulated) and adipose tissue lipoprotein lipase (LPL) activity were obtained. Plasma IL‐6 was measured by radioimmunoassay. Results: Plasma IL‐6 was positively correlated with total body fat mass (r = 0.32, P < 0.05), SC adipose tissue area (r = 0.35, P < 0.05), SC adipocyte diameter (r = 0.30, P < 0.05), and a trend was observed with visceral adipose tissue area (r = 0.20, P < 0.07). Plasma IL‐6 was positively correlated with glycerol released in response to isoproterenol (10^?5 to 10^?8 mol/l) by isolated SC (0.31 ≤ r ≤ 0.65, P < 0.05) and OM (0.36 ≤ r ≤ 0.40, P < 0.02) adipocytes, independent of menopausal status. No correlation was found with LPL activity. A subsample of women with high plasma IL‐6 (n = 10) was matched with women with low plasma IL‐6 (n = 10) for total body fat mass. OM adipocyte glycerol release in response to isoproterenol (10^?5 to 10^?8 mol/l) was higher in the subsample of women with elevated plasma IL‐6 (P ≤ 0.07). Discussion: We observed that OM lipolysis was significantly higher in women with elevated plasma IL‐6 for a similar body fat mass and menopausal status. These results suggest that higher circulating IL‐6 concentrations are associated with increased isoproterenol‐stimulated lipolysis especially in OM abdominal adipocytes in women.     

Acetylcholine potentiation of field stimulated rat vas deferens: A pre-synaptic muscarinic mechanism?

Acetylcholine (ACh) was found to markedly enhance the nerve stimulation induced twitch response of isolated, field-stimulated rat vas deferens (RVD). The ED₂₀₀ (concentration which enhances the twitch response to 200% of control) for this potentiation was 6 × 10^?6M with the maximum twitch response being increased by more than 3 fold (325 ± 30%). Carbachol (ED₂₀₀ = 8.5 × 10^?7M) showed identical results. With each drug the potentiation was competitively antagonized by atropine (10^?7?10^?5M). Physostigmine 10^?8?10^?6M) both enhanced the basal twitch response (215 ± 8% of control at 10^?5M) and the sensitivity of the RVD to ACh (ED₂₀₀ = 3.3 × 10^?7M) but not to carbachol. Atropine, on the other hand reduced the basal twitch response by 18 ± 3% at 10^?5M. Hemicholinium (10^?4M) also reduced the basal twitch responses by 23 ± 5%. ACh (10^?7M?10^?5M) did not modify the responses of unstimulated RVD to norepinephrine or KCl suggesting a pre-synaptic site of action. Taken together these results are compatible with the presence of a pre-junctional, excitatory muscarinic mechanism in the field stimulated RVD. That this cholinergic system may be of physiological significance is supported by the observations that atropine and hemicholinium depress while physostigmine enhances the twitch response in the absence of exogenous ACh.