Studies of the biosynthesis and metabolism of rat testicular galactoglycerolipids

1983 ◽  
Vol 61 (12) ◽  
pp. 1272-1281 ◽  
Author(s):  
Liu-Hsin Hsu ◽  
Rajagopalan Narasimhan ◽  
Mark Levine ◽  
Kenneth H. Norwich ◽  
Robert K. Murray
Keyword(s):  
Palmitic Acid ◽  
Early Stage ◽  
Turnover Time ◽  
Metabolic Stability ◽  
Cetyl Alcohol ◽  
Adult Rats ◽  
Slow Increase ◽  
Rat Testis ◽  
Specific Activities

1-O-Alkyl-2-O-acyl-3-O-β-D-(3′-sulfatoxygalactopyranosyl)-sn-glycerol (SGG) and its nonsulfated analog (GG) are the major glycolipids of rat testis. Aspects of the biosynthesis and metabolism of these two lipids have been investigated by determining their specific activities at various times after injection of [16-14C]palmitic acid, [1-14C]cetyl alcohol, and D-[1-14C]galactose into the testes of the adult rats. Evidence was obtained from studies with each of these three radioactive compounds that is consistent with the interpretation that GG exhibits a precursor relationship to SGG in vivo. The turnover time of GG, as estimated from the use of each of the three precursors, ranged between 21 and 69 h. In contrast, a slow increase of radioactivity in SGG was observed following injection of each of the three precursors, a plateau value being reached between 72 and 168 h. The radioactivity in the acyl, alkyl, and galactosyl moieties of SGG thereafter remained quite constant for another 21 days. Small amounts of monoalkylmonoacylglycerol were detected in rat testis. Radioactive studies indicated that this compound could be a precursor of GG and (or) monoalkyldiacylglycerol, another lipid that was also detected in rat testis. The results are consistent with the concept that the synthesis of SGG occurs primarily at an early stage of spermatogenesis and that the various moieties of this lipid exhibit almost complete metabolic stability during the subsequent complex stages of this process.

Surfactant metabolism of newborn lamb lungs studied in vivo

1980 ◽  
Vol 49 (6) ◽  
pp. 1091-1098 ◽  
Author(s):  
A. Jobe ◽  
M. Ikegami ◽  
I. Sarton-Miller ◽  
L. Barajas
Keyword(s):  
Palmitic Acid ◽  
Intravenous Injection ◽  
Half Life ◽  
Lamellar Body ◽  
Lung Parenchyma ◽  
Newborn Lamb ◽  
Specific Activities ◽  
Life Values ◽  
Surfactant Metabolism

Surfactant, microsomal, and lamellar body fractions were isolated from the lungs of 5-day-old lambs 0.21-55 h after the intravenous injection of radiolabeled palmitic acid. The specific activities as cpm/mumol phospholipid phosphate of phosphatidylcholine, saturated phosphatidylcholine, phosphatidylglycerol, and phosphatidylethanolamine were measured. The palmitate-labeled phospholipids disappeared from the lung parenchyma with a half-life of approximately 50 h. The radiolabel disappeared from phosphatidylcholine, saturated phosphatidylcholine, phosphatidylglycerol, and phosphatidylethanolamine of microsomal fractions with initial half-life values of 4.5, 4.6, 1.9, and 23.9 h, respectively. The labeled phospholipids rapidly appeared in the lamellar body fraction and accumulated in the surfactant of the lambs in a linear fashion for 35 h. The curves for the labeling of surfactant with radiolabeled saturated phosphatidylcholine, phosphatidylglycerol, and phosphatidylethanolamine were similar to the curve for phosphatidylcholine.

scholarly journals p-FAK-Tyr397 regulates spermatid adhesion in the rat testis via its effects on F-actin organization at the ectoplasmic specialization

2013 ◽  
Vol 305 (6) ◽  
pp. E687-E699 ◽  
Author(s):  
Hin-Ting Wan ◽  
Dolores D. Mruk ◽  
Stephen Y. T. Li ◽  
Ka-Wai Mok ◽  
Will M. Lee ◽  
...  
Keyword(s):  
Actin Polymerization ◽  
Early Stage ◽  
Regulatory Protein ◽  
Growth Factor Receptor ◽  
Actin Organization ◽  
Rat Testis ◽  
Mammalian Expression ◽  
Ectoplasmic Specialization ◽  
Stage Viii

During spermatogenesis, the molecular mechanism that confers spermatid adhesion to the Sertoli cell at the apical ectoplasmic specialization (apical ES), a testis-specific F-actin-rich adherens junction, in the rat testis remains elusive. Herein, the activated form of focal adhesion kinase (FAK), p-FAK-Tyr397, a component of the apical ES that was expressed predominantly and stage specifically in stage VII-early stage VIII tubules, was found to be a crucial apical ES regulator. Using an FAK-Y397E phosphomimetic mutant cloned in a mammalian expression vector for its transfection vs. FAK and vector alone in adult rat testes in vivo, its overexpression was found to cause defects in spermiation. These defects in spermiation were manifested by entrapment of spermatids in the seminiferous epithelium in late stage VIII–X tubules and were mediated by a disruption on the spatiotemporal expression and/or mislocalization of actin regulatory protein actin-related protein 3, which induces branched actin polymerization, epidermal growth factor receptor pathway substrate 8 (an actin barbed end capping and bundling protein), and palladin (an actin cross-linking and bundling protein). This thus perturbed changes of F-actin organization at the apical ES to facilitate spermiation, which also led to a concomitant alteration in the distribution and upregulation of adhesion proteins nectin-2 and nectin-3 at the apical ES. As such, nectin-2 and -3 remained at the apical ES to anchor step 19 spermatids on to the epithelium, delaying spermiation. These findings illustrate a mechanistic pathway mediated by p-FAK-Tyr397 that regulates spermatid adhesion at the apical ES in vivo.

Investigation of the potential role of the germ cell complement in control of the expression of transferrin mRNA in the prepubertal and adult rat testis

1997 ◽  
Vol 19 (1) ◽  
pp. 67-77 ◽  
Author(s):  
S M Maguire ◽  
M R Millar ◽  
R M Sharpe ◽  
J Gaughan ◽  
P T K Saunders
Keyword(s):  
Germ Cell ◽  
Mrna Expression ◽  
Germ Cells ◽  
Sertoli Cells ◽  
Direct Access ◽  
Adult Rats ◽  
Rat Testis ◽  
Adult Rat

ABSTRACT Iron is required for the normal development of germ cells during spermatogenesis. Because these cells have no direct access to systemic iron, there exists a shuttle system involving production and secretion of the iron-transporting protein transferrin by the Sertoli cells. Previous reports using cultures of immature Sertoli cells exposed to adult germ cells, or in vivo studies involving germ cell-depleted adult rat testes, concluded that production of transferrin by Sertoli cells is modulated by germ cell complement. In the present study we have used in situ hybridisation with cRNA probes directed against the 5′ and 3′ ends of transferrin mRNA to examine the pattern of expression of transferrin in the immature and adult rat testis. Adult rats were treated with ethane dimethane sulphonate or methoxyacetic acid (MAA) to manipulate their testosterone levels or germ cell complement respectively. Initial findings obtained using the 3′ probe showed a decrease in transferrin mRNA associated with round spermatid depletion. However, these data were not confirmed by in situ hybridisation when the 5′ probe was used. The specificity of the probes was examined using Northern blotting and the 3′ probe was found to hybridise to the germ cell transcript for hemiferrin even under conditions of high stringency. Examination of immature and pubertal rat testes by in situ hybridisation using the 5′ transferrin-specific probe found that as early as 14 days of age the level of expression of transferrin mRNA was clearly different between tubules, and the mRNA appeared to be expressed in Leydig cells on and after day 31. In the adult rat testis, maximal expression of transferrin mRNA was found at stages VIII-XIV, calling into question the interpretation of the results of some previous studies showing expression of transferrin mRNA at all stages of the spermatogenic cycle. This stage-specific pattern of expression was not altered by acute germ cell depletion using MAA. However, Northern blot analysis showed a statistically significant increase in transferrin mRNA expression at 7 days after MAA treatment when pachytene spermatocytes were depleted from tubules at all stages of the spermatogenic cycle at which transferrin is normally expressed. In conclusion, we found that transferrin mRNA expression was not modulated by round spermatids as has been reported previously but that meiotic germ cells may influence expression of transferrin at specific stages of the spermatogenic cycle.

scholarly journals D-Asp upregulates PREP and GluA2/3 expressions and induces p-ERK1/2 and p-Akt in rat testis

Reproduction ◽  
2019 ◽  
Vol 158 (4) ◽  
pp. 357-367 ◽  
Author(s):  
Alessandra Santillo ◽  
Massimo Venditti ◽  
Sergio Minucci ◽  
Gabriella Chieffi Baccari ◽  
Sara Falvo ◽  
...  
Keyword(s):  
Leydig Cells ◽  
Pivotal Role ◽  
Immunofluorescence Analysis ◽  
Adult Rats ◽  
Rat Testis ◽  
Germ Cell Differentiation ◽  
Ampa Receptor Subunit ◽  
The Central Nervous System ◽  
Hormone Homeostasis

D-Aspartate (D-Asp) is an endogenous amino acid that plays a central role in the development of the central nervous system (CNS) and functioning of the neuroendocrine system. In line with its functions, it is abundantly present in the CNS and reproductive systems of vertebrates and invertebrates. It has been implicated in the biosynthesis and/or secretion of hormones and factors that are involved in various reproductive functions, such as GnRH from the hypothalamus and testosterone from the testis. We conducted an in vivo study consisting of acute (i.p. injection of 2 µmol/g body weight) and chronic (15 days drinking solution) administration of D-Asp to adult rats to understand the signaling pathways elicited by D-Asp in the rat testis. We found that D-Asp upregulated the expression of prolyl endopeptidase (PREP), a serine protease having a pivotal role in the regulation of mammalian spermatogenesis and spermiogenesis. Immunofluorescence analysis revealed its overexpression in Leydig cells, Sertoli cells and spermatogonia. Moreover, PREP was found to co-localize with GluA2/3, an AMPA receptor subunit, whose protein expression also increased after D-Asp treatments. Finally, we found a significant increase in ERK and Akt activities in the testis of rats treated with D-Asp. Since PREP is known to be involved in regulating GnRH levels and in germ cell differentiation, we hypothesize D-Asp to play a pivotal role in regulating hormone homeostasis and spermatogenesis through activation of PREP, AMPAR, ERK and Akt.

scholarly journals Fascin 1 is an actin filament-bundling protein that regulates ectoplasmic specialization dynamics in the rat testis

2014 ◽  
Vol 307 (9) ◽  
pp. E738-E753 ◽  
Author(s):  
N. Ece Gungor-Ordueri ◽  
Ciler Celik-Ozenci ◽  
C. Yan Cheng
Keyword(s):  
Mammalian Cells ◽  
Early Stage ◽  
Seminiferous Epithelium ◽  
Permeability Barrier ◽  
Actin Organization ◽  
Rat Testis ◽  
Ectoplasmic Specialization ◽  
Stage Viii

In the testis, spermatids are polarized cells, with their heads pointing toward the basement membrane during maturation. This polarity is crucial to pack the maximal number of spermatids in the seminiferous epithelium so that millions of sperms can be produced daily. A loss of spermatid polarity is detected after rodents are exposed to toxicants (e.g., cadmium) or nonhormonal male contraceptives (e.g., adjudin), which is associated with a disruption on the expression and/or localization of polarity proteins. In the rat testis, fascin 1, an actin-bundling protein found in mammalian cells, was expressed by Sertoli and germ cells. Fascin 1 was a component of the ectoplasmic specialization (ES), a testis-specific anchoring junction known to confer spermatid adhesion and polarity. Its expression in the seminiferous epithelium was stage specific. Fascin 1 was localized to the basal ES at the Sertoli cell-cell interface of the blood-testis barrier in all stages of the epithelial cycle, except it diminished considerably at late stage VIII. Fascin 1 was highly expressed at the apical ES at stage VII–early stage VIII and restricted to the step 19 spermatids. Its knockdown by RNAi that silenced fascin 1 by ∼70% in Sertoli cells cultured in vitro was found to perturb the tight junction-permeability barrier via a disruption of F-actin organization. Knockdown of fascin 1 in vivo by ∼60–70% induced defects in spermatid polarity, which was mediated by a mislocalization and/or downregulation of actin-bundling proteins Eps8 and palladin, thereby impeding F-actin organization and disrupting spermatid polarity. In summary, these findings provide insightful information on spermatid polarity regulation.

Characterization of the regenerated Leydig cell population of the rat after destruction by ethylene-1,2-dimethanesulphonate

1988 ◽  
Vol 117 (1) ◽  
pp. 11-18 ◽  
Author(s):  
G. Edwards ◽  
W. R. Robertson ◽  
I. D. Morris
Keyword(s):  
Leydig Cells ◽  
Normal Serum ◽  
Serum Concentrations ◽  
Adult Rats ◽  
Rat Testis ◽  
Adult Rat ◽  
Fetal Rat ◽  
Old Rats ◽  
Two Peaks

ABSTRACT The Leydig cells repopulating the adult rat testis after destruction by a single injection of the cytotoxic ethylene-1,2-dimethanesulphonate (EDS) were investigated. After 14 days, serum concentrations of LH and FSH were significantly raised and concentrations of testosterone in the serum and testis reduced. At 21 days, hormone concentrations had returned to within the normal range. Binding of 125I-labelled human chorionic gonadotrophin (hCG) to testis homogenate, however, was still less than 10% of normal. After 21 or 28 days the 125I-labelled hCG binding profiles of isolated Leydig cells from EDS-treated rats, separated on a Percoll gradient, showed a single peak similar to that of immature (25 days old) rats. After 49 days, 125I-labelled hCG binding resolved into two peaks more like that of normal adult rats. Using a quantitative cytochemical method, 3β-hydroxysteroid dehydrogenase activity in individual Leydig cells of unfixed testis sections was determined. Activity was increased by 70% (P < 0·05) in repopulating Leydig cells 21 days after EDS treatment compared with cells from vehicle-treated rats. In addition, Leydig cells were still capable of further 'in-vivo' stimulation by pharmacological doses of hCG. These data indicate that Leydig cells repopulating the testis are homogenous. Fewer cells from the newly formed population are capable of maintaining normal serum concentrations of testosterone and must thus be individually more active in secreting testosterone. In these respects, the Leydig cells repopulating the adult rat testis after EDS treatment more closely resemble those of the fetal rat testis. J. Endocr. (1988) 117, 11–18

Lipid synthesis by the monoglyceride and α-glycerophosphate pathways in sheep intestine

1969 ◽  
Vol 47 (11) ◽  
pp. 1013-1020 ◽  
Author(s):  
H. M. Cunningham ◽  
W. M. F. Leat
Keyword(s):  
Palmitic Acid ◽  
Lipid Synthesis ◽  
Adult Rats ◽  
Adult Sheep ◽  
Glyceride Synthesis ◽  
Intestinal Segments ◽  
Hydrolysis Of

Double-labelled monopalmitin containing 14C-glycerol and 3H-palmitic acid was used in vitro in intestinal segments and in vivo in intestinal loops of sheep to determine if triglycerides could be synthesized by both the monoglyceride and α-glycerophosphate pathways. Total glyceride synthesis in vitro by the combined pathways was highest in 87- and 120-day foetal lambs, followed in declining order by 6- to 13-day lambs, adult sheep, and adult rats (used for comparative purposes). The minimum percentage of the glycerides synthesized by the monoglyceride pathway using 1-monopalmitin as a precursor was: foetus 20, lamb 29, adult sheep 28, and rat 45. These are minimum values because appreciable hydrolysis of 1-monopalmitin occurred during incubation: 61% in rats, 68% in lambs, 71% in adult sheep, and 80% in foetal sheep. 2-Monopalmitin was more resistant to hydrolysis by intestinal segments and loops and resulted in at least 43% synthesis of glycerides by the monoglyceride pathway in segments of adult sheep intestine, compared to 26% with 1-monopalmitin.

scholarly journals Lipid metabolism in the testis of the ram

1968 ◽  
Vol 107 (2) ◽  
pp. 273-278 ◽  
Author(s):  
T. W. Scott ◽  
B. P. Setchell
Keyword(s):  
Lipid Metabolism ◽  
Luteinizing Hormone ◽  
Phosphatidic Acid ◽  
Palmitic Acid ◽  
Neutral Lipids ◽  
Follicle Stimulating Hormone ◽  
Specific Radioactivity ◽  
Testicular Artery ◽  
Rat Testis

1. Analysis of rams testes revealed that phosphatidylcholine was the major phospholipid and accounted for about 40% of the total. Only small amounts of choline plasmalogen were present. 2. The ratio of phosphatidylcholine to choline plasmalogen in the testis was very different from that occurring in the spermatozoa. This result was in contrast with those for rat testis and rat spermatozoa (obtained from the head of the epididymis), where the ratio of the two lipids was very similar. 3. Infusions of [32P]orthophosphate into the testicular artery of rams resulted in incorporation of radioactivity into most phospholipids; phosphatidylinositol labelling accounted for 68% and 39% of the radioactivity after infusions lasting 3hr. and 5hr. respectively. 4. With the exception of phosphatidic acid the specific radioactivity of phosphatidylinositol was higher than that of any other lipid. 5. After the infusion of [U−14C]glucose, triglycerides accounted for about 60% of the radioactivity in testicular neutral lipids, whereas diglycerides had only about 15% of the radioactivity. 6. Palmitic acid (16:0) was the major component both in neutral lipids and phospholipids of ram testes. 7. The effects of gonadotrophic hormones (luteinizing hormone and follicle-stimulating hormone) on the incorporation of [32P]orthophosphate into total testicular phospholipids in vivo were also examined.

Adenosine Diphosphate (ADP)-Induced ⍺-Granules Release from Platelets of Native Whole Blood Is Reduced by Ticlopidine but Not by Aspirin or Dipyridamole

1986 ◽  
Vol 56 (02) ◽  
pp. 147-150 ◽  
Author(s):  
V Pengo ◽  
M Boschello ◽  
A Marzari ◽  
M Baca ◽  
L Schivazappa ◽  
...  
Keyword(s):  
Whole Blood ◽  
Light Transmission ◽  
Ex Vivo ◽  
Early Stage ◽  
Shape Change ◽  
Adenosine Diphosphate ◽  
Dose Dependent ◽  
Plateletderived Growth Factor ◽  
Platelet Shape

SummaryA brief contact between native whole blood and ADP promotes a dose-dependent release of platelet a-granules without a fall in the platelet number. We assessed the “ex vivo” effect of three widely used antiplatelet drugs, aspirin dipyridamole and ticlopidine, on this system. Aspirin (a single 800 mg dose) and dipyridamole (300 mg/die for four days) had no effect, while ticlopidine (500 mg/die for four days) significantly reduced the a-granules release for an ADP stimulation of 0.4 (p <0.02), 1.2 (p <0.01) and 2 pM (p <0.01). No drug, however, completeley inhibits this early stage of platelet activation. The platelet release of α-granules may be related to platelet shape change of the light transmission aggregometer and may be important “in vivo” by enhancing platelet adhesiveness and by liberating the plateletderived growth factor.

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