Growth and protein metabolism in exercised, estrogen-fed and developing female Zucker rats

Defective protein metabolism in association with subnormal lean body mass has been proposed as an underlying factor in the obesity of the Zucker rat. In contrast to the obese male Zucker rat, obese female rats maintain normal or above normal lean body weight despite the obesity;In Experiment 1, female Zucker rats were treadmill exercised from 12 to 17 weeks of age. Exercise decreased percent carcass fat and increased lean carcass weight of lean rats but not of obese rats. Although exercise did not affect 3-methylhistidine (3-MH) excretion in either genotype, obese rates excreted more 3-MH than lean rats did;In Experiment 2, female Zucker rats were fed ethynyl estriadiol (EE) from 10 to 18 weeks of age. Obese rats were more sensitive to EE feeding than lean rats were. EE feeding decreased lean carcass weight more markedly in obese than in lean rats. EE feeding in obese rats resulted in decreased heart, liver and spleen weights; whereas, in lean rats, heart and liver, but not spleen, weights were decreased by EE feeding. EE feeding had no effect on 3-MH excretion in either genotype;In Experiment 3, 25-day-old and 10-week-old female Zucker rats were injected with (\u273)H-phenylalanine and incorporation of label into muscle and liver protein was measured. Obese 25-day-old rats incorporated less label into both muscle and liver protein than lean rats did. However, obese rats excreted less 3-MH than lean rats did. At 10 weeks of age, incorporation of label into liver and muscle protein and excretion of 3-MH were similar for lean and obese rats;These results support the hypothesis that defective protein metabolism is an underlying factor in the obesity of the female Zucker rat even though lean body mass is normal

Mammalian oocytes are targets for prostaglandin E2 (PGE2) action

<p>Abstract</p> <p>Background</p> <p>The ovulatory gonadotropin surge increases synthesis of prostaglandin E2 (PGE2) by the periovulatory follicle. PGE2 actions on granulosa cells are essential for successful ovulation. The aim of the present study is to determine if PGE2 also acts directly at the oocyte to regulate periovulatory events.</p> <p>Methods</p> <p>Oocytes were obtained from monkeys and mice after ovarian follicular stimulation and assessed for PGE2 receptor mRNA and proteins. Oocytes were cultured with vehicle or PGE2 and assessed for cAMP generation, resumption of meiosis, and in vitro fertilization.</p> <p>Results</p> <p>Germinal vesicle intact (GV) oocytes from both monkeys and mice expressed mRNA for the PGE2 receptors EP2, EP3, and EP4. EP2 and EP4 proteins were detected by confocal microscopy in oocytes of both species. Monkey and mouse oocytes responded to PGE2 as well as agonists selective for EP2 and EP4 receptors with elevated cAMP, consistent with previous identification of EP2 and EP4 as Gαs/adenylyl cyclase coupled receptors. Incubation of mouse GV stage oocytes with PGE2 delayed oocyte nuclear maturation in vitro, but PGE2 treatment did not alter the percentage of mouse oocytes that fertilized successfully. PGE2 treatment also decreased the percentage of monkey oocytes that resumed meiosis in vitro. In contrast with mouse oocytes, the percentage of monkey oocytes which fertilized in vitro was lower after treatment with PGE2. Monkey oocytes with intact cumulus showed delayed nuclear maturation, but fertilization rate was not affected by PGE2 treatment.</p> <p>Conclusions</p> <p>Monkey and mouse oocytes express functional PGE2 receptors. PGE2 acts directly at mammalian oocytes to delay nuclear maturation. Surrounding cumulus cells modulate the effect of PGE2 to alter subsequent fertilization.</p

High quality sperm for nonhuman primate ART: Production and assessment

Abstract Factors that affect sperm quality can include method of semen collection, conditions for capacitation and whether or not agglutination is present. Media and procedures for sperm washing can also impair or improve sperm function in assisted reproductive technologies. For example, the removal of seminal fluid through large volume washing is required to eliminate decapacitation activity of seminal plasma. The forces involved with centrifugation and the metabolic stress of tightly pelleting sperm during washing procedures can have deleterious results. In contrast to human sperm, sperm from the most commonly used species of nonhuman primates, rhesus and cynomolgus macaques, do not spontaneously capacitate in vitro; rather, chemical activation with dibutryl cyclic AMP and caffeine is required. Recognizing motility patterns of non-activated and activated sperm can be accomplished with simple observation. After activation, sperm agglutination sometimes occurs and can interfere with sperm binding to the zona pellucida. Because nonhuman primate oocytes require a large investment to produce and currently, each animal can be hormonally stimulated a limited number of times, it is important to have means to evaluate quality prior to using sperm from a new male for in vitro fertilization. Methods for producing live, acrosome reacted sperm may also have application for ICSI. Because many genetically valuable males are now being identified, it may be necessary to individualize sperm preparation to accommodate male-to-male variation.</p

The efficacy of ultrasound treatment as a reversible male contraceptive in the rhesus monkey

AbstractBackgroundThe use of therapeutic ultrasound as a contraceptive approach has involved nonhuman primates as well as rats and dogs. The current study was undertaken to determine whether this treatment could be a method for reversible contraception, using a model with testes size similar to adult humans.MethodsTwo methods of ultrasound exposure were used, either the transducer probe at the bottom of a cup filled with saline (Cup) or direct application to the surface of the scrotum (Direct). Four adult rhesus (Macaca mulatta) males with normal semen parameters were treated with therapeutic ultrasound at 2.5 W/cm(2) for 30 min. Treatment was given 3 times, one every other day on a Monday-Wednesday-Friday schedule. For each male, semen quality was evaluated a minimum of three times over several months prior to ultrasound exposure and weekly for two months following ultrasound treatment.ResultsSemen samples from all males, regardless of exposure method, exhibited a decrease in the percentage of motile sperm following ultrasound treatment. There was an average reduction in motility of 40% the week following treatment. Similarly, curvilinear velocity and the percentage of sperm with a normally shaped flagellum were also reduced in all males following ultrasound treatment. A significant reduction in the total number of sperm in an ejaculate (total sperm count) was only observed in males that received ultrasound via the cup method. Following treatment via the cup method, males exhibited up to a 91.7% decrease in average total sperm count (n = 2). Sperm count did not approach pre-treatment levels until 8 weeks following ultrasound exposure.ConclusionsThe sustained reduction in sperm count, percent motility, normal morphology, and sperm vigor with the cup exposure method provides proof of principle that testicular treatment with ultrasound can be an effective contraceptive approach in humans

The efficacy of ultrasound treatment as a reversible male contraceptive in the rhesus monkey

Abstract Background The use of therapeutic ultrasound as a contraceptive approach has involved nonhuman primates as well as rats and dogs. The current study was undertaken to determine whether this treatment could be a method for reversible contraception, using a model with testes size similar to adult humans. Methods Two methods of ultrasound exposure were used, either the transducer probe at the bottom of a cup filled with saline (Cup) or direct application to the surface of the scrotum (Direct). Four adult rhesus (Macaca mulatta) males with normal semen parameters were treated with therapeutic ultrasound at 2.5 W/cm(2) for 30 min. Treatment was given 3 times, one every other day on a Monday-Wednesday-Friday schedule. For each male, semen quality was evaluated a minimum of three times over several months prior to ultrasound exposure and weekly for two months following ultrasound treatment. Results Semen samples from all males, regardless of exposure method, exhibited a decrease in the percentage of motile sperm following ultrasound treatment. There was an average reduction in motility of 40% the week following treatment. Similarly, curvilinear velocity and the percentage of sperm with a normally shaped flagellum were also reduced in all males following ultrasound treatment. A significant reduction in the total number of sperm in an ejaculate (total sperm count) was only observed in males that received ultrasound via the cup method. Following treatment via the cup method, males exhibited up to a 91.7% decrease in average total sperm count (n = 2). Sperm count did not approach pre-treatment levels until 8 weeks following ultrasound exposure. Conclusions The sustained reduction in sperm count, percent motility, normal morphology, and sperm vigor with the cup exposure method provides proof of principle that testicular treatment with ultrasound can be an effective contraceptive approach in humans.</p

Invalid controls undermine conclusions of FDA studies.

This issue of Toxicological Sciences features several exciting changes: a redesigned cover, revised category subheadings, and this "Look Inside ToxSci" feature. Together with my esteemed colleagues in the field of green chemistry, we have outlined some exciting opportunities for the field of toxicology in the editorial on green chemistry and toxicology. There are insightful articles on the regulatory challenges regarding mixtures that are being addressed by the European Union and on risk assessment of carbon nanotubes. In the past, we have highlighted a single article from each issue. It has become increasingly difficult to select just one article from the volume of high quality work, so beginning this month we will highlight multiple articles in each issue here in "Look Inside ToxSci." From solvents, pesticides, and nanoparticles to the microbiome, the highlighted articles span the breadth of our field. Of course, this issue contains something that will never change; our raison d'etre …the best original research in the field of toxicology. -Gary W. Miller