High fat-induced obesity associated with insulin-resistance increases FGF-2 content and causes stromal hyperplasia in rat ventral prostate

Obesity affects sex hormone secretion, which can negatively influence prostatic structure, homeostasis, and disease. This investigation aimed to evaluate the repercussions of obesity induced by a high-fat diet on the rat prostate, with or without treatment with the aromatase inhibitor, Letrozole. Adult Wistar rats were fed a high-fat diet (20% saturated fat, O) for 15 weeks to induce obesity or received a balanced diet (4% fat, C). Then, a group of C and O rats were daily treated with Letrozole (1 mg/kg b.w. per day) for 2 weeks (CL and OL, respectively). Subsequently, ventral prostate was processed for analysis by transmission electron microscopy, immunohistochemistry, and Western blotting. Obesity decreased 70% of the testosterone plasma level. The prostate showed epithelial atrophy and dilated acini in the intermediate portion and epithelial wrinkling in the distal tips. The relative frequency of smooth muscle alpha-actin in the O group increased by 67%. Ultrastructurally, epithelial cells in obese animals presented altered secretory organelles, lipid droplets, and thicker subjacent fibromuscular layer. Letrozole treatment caused a partial restoration of the prostatic changes caused by obesity. Obesity increased the prostatic content of fibroblast growth factor-2 (FGF-2) by 150%, and Letrozole treatment increased this protein even more in the control and obese groups. This investigation shows that obesity provokes structural and ultrastructural changes in the epithelium of rat prostate; these changes might affect gland homeostasis and physiology. The epithelial and smooth muscle cell hyperplasia and increased FGF-2 expression observed in this experimental model of obesity/insulin-resistance might explain the high frequency of benign prostatic hyperplasia in insulin-resistant men.

Lobe identity in the Mongolian gerbil prostatic complex: A new rodent model for prostate study

Knowledge of structural and physiological differences among the prostatic lobes (PL) is the basis for development of experimental studies in traditional laboratory rodents. Although Mongolian gerbil reproductive organs have been increasingly investigated, its prostate structure is far from being properly known, and investigations of this organ focused on the ventral lobe (VL). Thus, the present study provides a thorough morphological description of prostatic complex in the male adult gerbil on the basis of topographic, histological, and ultrastructural analysis and ductal branching. Like other rodents, four pairs of PL were observed. However, in contrast to the rat and mouse, the VL is the least voluminous component and the dorsolateral lobe (DLL) is the most prominent and spatially isolated from remaining PL. The occurrence of a dorsal lobe (DL), hidden between bladder and insertion of seminal vesicles, has not been mentioned in previous reports with Mongolian gerbil. Collagenase digestion followed by microdissection revealed that, except for DL, which has a tubularacinar organization, all PL exhibit tubular organization and variable ductal branching. Distinct histological and ultrastructural features such as secretory epithelium, aspect of luminal secretion and stromal organization are reported for each PL and are confirmed by morphometric and stereological methods. Histological sections showed at least three intralobar segments in VL and DL. Ultrastructural analysis evidenced that, although luminal epithelial cells of PL share typical features of exocrine secretory cells, there are striking lobe phenotypical variations. Both merocrine and apocrine pathways are observed in variable rates in all PL, with the predominance of the former in the DLL and the latter in the CG. The morphological observations presented herein point to distinct structural identities for each PL, which probably reflects,specific functional compromise of seminal fluid secretion. These data also point to the gerbil as a good model for investigations concerning the regulation of prostate development and homeostasis, mainly with regard to the dorsal and dorsolateral PL.

Interaction of octaethylene glycol n-dodecyl monoether with dioctadecyldimethylammonium bromide and chloride vesicles

Several different methods were used to investigate the vesicle-to-micelle transition induced by the addition of the nonionic surfactant octaethylene glycol n-dodecyl monoether (C12E8) to spontaneously formed vesicle dispersions of dioctadecyldimethylammonium bromide and chloride (DODAX, X = Cl- and Br-). Dynamic light scattering reveals that fast mode micelles are formed upon addition of C12E6. The micellar mode becomes progressively dominant as the C12E8/DODAX molar ratio (R) is increased until the vesicle-to-micelle transition is complete. Turbidity, calorimetry, fluorescence quantum yield, and anisotropy measurements indicate two critical compositions: the first, R-sat, when the vesicle bilayer is saturated with C12E8 and the second, R-sol, which corresponds to the complete vesicle-to-micelle transition. Below R-sat the vesicles swell due to incorporation of the surfactant into the vesicle bilayer, and above R-sat mixed micelles and bilayer structures coexist, the determined R-sat and R-sol range from 0 to 1 and 4 to 6, respectively, depending on the surfactant counterion and the experimental method used. Cryo-transmission electron microscopy micrographs show that when R approximate to 4, micelles coexist with extended bilayer fragments. In pure DODAX (1.0 mM) dispersions, unilamellar vesicles are observed. According to the DSC results, C12E8 lowers the gel-to-liquid crystalline transition temperature, T-m, of DODAX and broadens the main transition peak which disappears around R approximate to 5 and 6 for DODAC and DODAB, respectively.

Interaction of sodium cholate with dioctadecyldimethylammonium chloride vesicles in aqueous dispersion

Mixtures of dioctadecyldimethylammonium chloride (DODAC) cationic vesicle dispersions with aqueous micelle solutions of the anionic sodium cholate (NaC) were investigated by differential scanning calorimetry, DSC, turbidity and light scattering. Within the concentration range investigated (constant 1.0 mM DODAC and varying NaC concentration up to 4 mM), vesicle -> micelle -> aggregate transitions were observed. The turbidity of DODAC/NaC/water depends on time and NaC/DODAB molar concentration ratio R. At equilibrium, turbidity initially decreases smoothly with R to a low value (owing to the vesicle-micelle transition) when R = 0.5-0.8 and then increases steeply to a high value (owing to the micelle-aggregate transition) when R = 0.9-1.0. DSC thermograms exhibit a single and sharp endothermic peak at T-m approximate to 49 degrees C, characteristic of the melting temperature of neat DODAC vesicles in water. Upon addition of NaC, T-m initially decreases to vanish around R = 0.5, and the main transition peak broadens as R increases. For R > 1.0 two new (endo- and exothermic) peaks appear at lower temperatures indicating the formation of large aggregates since the dispersion is turbid. All samples are non-birefringent. Dynamic light scattering (DLS) data indicate that both DODAC and DODAC/NaC dispersions are highly polydisperse, and that the mean size of the aggregates tends to decrease as R increases. (c) 2006 Elsevier B.V. All rights reserved.

Structural and thermal characterization of dioctadecyldimethylammonium bromide dispersions by spin labels

Dioctadecyldimethylammonium bromide (DODAB) dispersions obtained by simply mixing the amphiphile in water, and by bath-sonication, were investigated by electron spin resonance (ESR) of stearic acids and their methyl ester derivatives, labeled at the 5th and 16th carbons of the acyl chain. The ESR spectra indicate that the non-sonicated dispersions are formed mainly by one population of DODAB vesicles, either in the gel (T < T-m) or in the liquid-crystalline (T > T-m) state. Around T-m there is a co-existence of the two phases, with a thermal hysteresis of about 3.2 degreesC. In sonicated DODAB dispersions, spin labels indicate two different environments even for temperatures far below T-m: one similar to that obtained with non-sonicated samples, a gel phase, and another one in the liquid-crystalline state. The fluid phase domain present below T-m could correspond to either the periphery of bilayer fragments, reported to be present in sonicated DODAB dispersions, or to high curvature vesicles. (C) 2001 Elsevier B.V. Ireland Ltd. All rights reserved.

Phase transition in dioctadecyldimethylammonium bromide and chloride vesicles prepared by different methods

The gel to liquid crystalline phase transition of the double-chained cationic dioctadecyldimethylammonium chloride and bromide (DODAX, X = Cl- or Br-) in aqueous vesicle dispersions prepared by non-sonication, sonication and extrusion has been investigated using high-sensitivity differential scanning calorimetry (DSC). The transition temperature (T-m) is a function of the preparation method, amphiphile concentration, vesicle curvature and nature of the counterion. DSC thermograms for DODAB and DODAC non-sonicated vesicle dispersions exhibit a single endothermic peak at T-m roughly independent of concentration up to 10 mM. Extrusion broadens the transition peak and shifts T-m downwards. Sonication, however, broadens slightly the transition peak and tends to shift T-m upwards suggesting that extrusion and sonication form vesicles with different characteristics. DODAC always exhibits higher T-m than DODAB irrespective of the preparation method. T-m changes as follows: T-m (sonicated) greater than or equal to T-m (non-sonicated) > T-m (extruded). Hysteresis of about 7 degrees C was observed for DODAB vesicle dispersions. (C) 2000 Elsevier B.V. Ireland Ltd. All rights reserved.

The effect of ionic strength on the structural organization of dioctadecyldimethylammonium bromide in aqueous solution

High-curvature and stabilized vesicles of dioctadecyldimethylammonium bromide (DODABr) can be formed spontaneously in aqueous electrolytic solution. It is shown by cryo-transmission electron microscopy that 5.0 mM DODABr molecules associate in water at a temperature above its gel-to-liquid-crystalline phase transition temperature (T(m)approximate to45 degreesC) in a variety of complex bilayer structures. However, in the presence of NaCl the preferred structures formed are unilamellar and bilamellar vesicles with high curvature and the dispersion is polydisperse in size and geometry, but the main vesicle population contains spherical, flattened and smoothed structures. It is, however, less polydisperse than the corresponding salt-free dispersion, and the size polydispersity and the vesicle curvature radius tend to decrease with NaCl concentration. Long cylindrical bilamellar vesicles, with a very thin water layer separating the bilayers are also formed in the presence of 10 mM NaCl. The effect of the ionic strength on T-m, obtained by differential scanning calorimetry, is shown to depend on the nature of the counterion: Br- decreases, whereas Cl- increases Tm of DODABr, indicating different affinity of these counterions for the vesicle surfaces.

The effect of chain length on the melting temperature and size of dialkyldimethylammonium bromide vesicles

Differential scanning calorimetry (DSc) and dynamic light scattering (DLS) were used to obtain the gel to liquid-crystalline phase transition temperature (T-m) and the apparent hydrodynamic radius (R-h) of spontaneously formed cationic vesicles of dialkyldimethylammonium bromide salts (CnH2n+1)(2)(CH3)(2)N+center dot Br-, with varying chain lengths. The preparation of cationic vesicles from aqueous solution of these surfactants, for n = 12, 14, 16 and 18 (DDAB, DTDAB, DHDAB and DODAB, respectively), requires the knowledge of the surfactant gel to liquid-crystalline phase transition temperature, or melting temperature (T-m) since below this temperature these surfactants are poorly or not soluble in water. That series of cationic surfactants has been widely investigated as vesicle-forming surfactants, although C-12 and C-18, DDAB and DODAB are by far the most investigated from this series. The dependence of T-m of these surfactants on the number n of carbons in the surfactant tails is reported. The T-m obtained by DSC increases non-linearly with n, and the vesicle apparent radius R-h is about the same for DHDAB and DODAB, but much smaller for DDAB. (c) 2006 Elsevier B.V.. All rights reserved.

Effect of Sonication on the Thermotropic Behavior of DODAB Vesicles Studied by Fluorescence Probe Solubilization

The effect of sonication on fluorescence probe solubilization in cationic vesicles of dioctadecyldimethylammonium bromide (DODAB) was investigated by steady-state fluorescence of pyrene (Py), trans-diphenylpolyenes-diphenylbutadiene (DPB), diphenylhexatriene (DPH), and their corresponding 4,4'-dialkyl derivatives 4B4A and 4H4A fluorescence probes. The data indicate that sonication affects the bilayer polarity, the melting temperature (T (m)), and the cooperativity of the melting process due to changes in vesicle morphology. The effect of temperature on the fluorescence intensity and yielding I broken vertical bar(f) and anisotropy < r > shows that the ionizable probes 4B4A and 4H4A are solubilized close to the vesicle interfaces, whereas the non-ionizable DPH and DPB are deeper in the bilayers. Py solubilization indicates that sonicated vesicles exhibit less densely packed bilayers.

Interactions of mast cell degranulating peptides with model membranes: A comparative biophysical study

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Extruded vesicles of dioctadecyldimethylammonium bromide and chloride investigated by light scattering and cryogenic transmission electron microscopy

Combined dynamic and static light scattering (DLS, SLS) and cryogenic transmission electron microscopy (cryo-TEM) were used to investigate extruded cationic vesicles of dioctadecyldimethylammonium chloride and bromide (DODAX, X being Cl- or Br-). In salt-free dispersions the mean hydrodynamic diameter, D-h, and the weight average molecular weight, M-w, are larger for DODAB than for DODAC vesicles, and both D-h and M-w increase with the diameter (phi) of the extrusion filter. NaCl (NaBr) decreases (increases) the DODAB (DODAC) vesicle size, reflecting the general trend of DODAB to assemble as larger vesicles than DODAC. The polydispersity index is lower than 0.25, indicating the dispersions are rather polydisperse. Cryo-TEM micrographs show that the smaller vesicles are spherical while the larger ones are oblong or faceted, and the vesicle samples are fairly polydisperse in size and morphology. They also indicate that the vesicle size increases with phi and DODAB assembles as larger vesicles than DODAC. Lens-shaped vesicles were observed in the extruded preparations. Both light scattering and cryo-TEM indicate that the vesicle size is larger or smaller than phi when phi is smaller or larger than the optimal phi* approximate to 200 nm. (C) 2008 Elsevier B.V. All rights reserved.

Interaction between Pluronic F127 and Dioctadecyldimethylammonium Bromide (DODAB) Vesicles Studied by Differential Scanning Calorimetry

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

DODAB and DODAC bilayer-like aggregates in the micromolar surfactant concentration domain

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Kinetic asymmetry in the gel-liquid crystalline state transitions of DDAB vesicles studied by differential scanning calorimetry

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Spontaneous vesicles of sodium dihexadecylphosphate in HEPES buffer

The formation of spontaneous vesicles of dihexadecylphosphate (DHP) in a HEPES buffered solution at pH 7.4, the size, morphology and melting temperature, obtained by cryogenic transmission electron microscopy (cryo-TEM) and differential scanning calorimetry (DSC), are reported. The vesicles were formed by simply mixing a 5.0 mM lipid-solvent mixture at a temperature (75 degrees C) safely above the higher melting temperature T-m = 70.4 degrees C of DHP. The vesicle diameter ranges from 100 to 332 nm and their geometry is spherical, faceted or oblong. T-m increases from 66.8 to 70.4 as DHP concentration is raised from 0.6 to 5.0 mM. (c) 2008 Elsevier B.V. All rights reserved.