Food restriction during pregnancy in rabbits: effects on hormones and metabolites involved in energy homeostasis and metabolic programming.

This study examined the effects of food restriction during rabbit pregnancy on hormones and metabolites involved in energy homeostasis and metabolic programming. Pregnant does were assigned to four groups: the control group was fed a standard ration while the others received a restricted amount of food (30% restriction) during early (0-9 days), mid (9-18 days), and late (19-28 days) pregnancy. The pregnancy induced a coordinated range of adaptations to fulfil energy requirements of both mother and foetus, such as hyperleptinaemia and hyperinsulinaemia, reduced insulin sensitivity, increased cortisol and non-esterified fatty acid. Food restriction altered leptin, insulin, T3, non-esterified fatty acids and glucose concentrations depending on the gestational phase in which it was applied. Collectively, present data confirm that the endocrinology of pregnancy and the adaptive responses to energy deficit make the rabbit an ideal model for studying nutritional-related disorders and foetal programming of metabolic disease.

Induction of ovulation in rabbits by adding Lecirelin to the seminal dose: in vitro and in vivo effects of different excipients.

This study evaluates the effect of Lecirelin (Dalmarelin(®), Fatro, Italy) diluted in different excipients (benzilic alcohol, benzoic acid and paraben) added to a seminal dose on LH concentrations, progesterone concentrations and ovarian status in rabbits. The in vitro effect on spermatozoa was also tested. A total of 100 multiparous female rabbits were divided into 5 groups, which at the moment of AI, received 0.2 mL (5 µg/dose) intramuscular (im) inoculation of Lecirelin (control) or the same Lecirelin dose administered intravaginally (iv) with the seminal dose alone (Lecirelin group) or with benzilic alcohol (Lecirelin BA group), benzoic acid (Lecirelin BAc group) or parabens (Lecirelin PA group) as an excipient. After 7 days, 10 rabbits per group were euthanized to analyze their ovarian status. In the control group, a high LH peak was detected 30 min post AI, while in the iv groups a slight increase in LH occurred after 120 min. The ovulation and fertility rate was similar in control and Lecirelin groups, while the lowest fertility rate was detected in the Lecirelin BA group. In a second experiment, the semen samples collected from male rabbits were diluted in TALP (control) or mixed with the 5 µg of Lecirelin solutions used in the first experiment. The highest percentage of capacitated sperm (68.3%) was recorded in the Lecirelin PA. The lowest percentages were observed in the Lecirelin BA and BAc groups. In conclusion, the iv administration of Lecirelin represents an alternative method for simplifying rabbit insemination procedures.

Effects of a bacterial lipopolysaccharide on the reproductive functions of rabbit does.

Systemic and local infections and inflammations are known to cause infertility in humans and animals. However, the mechanisms by which infection/inflammation induces infertility are only partially known. The objectives of this study were: (i) to provide models of systemic (acute) and local (sub-acute) inflammation by intra-peritoneal injection or intra-cervical deposition of lipopolysaccharide (LPS) in the rabbit and (ii) to assess their effects on uterine tissues and sperm transport in the genital tract of rabbit does. Intra-peritoneal administration of different doses of LPS induced systemic effects such as fever, anorexia and changes in white blood cells (WBC) count. In our study, LPS inoculation (100µg/kg) produced an inflammation-like status that lasted for about 3 days, with minimal distress for the animals. Intra-peritoneal administration of LPS 60h before artificial insemination induced a rapid increase of IL-1ß concentrations. The intra-cervical inoculation of LPS did not show any systemic effects, as confirmed by the lack of changes in body temperature, feed intake and WBC count. Histological examination of uterine tissues showed an endometritis-like inflammation status in LPS-treated does, more severe in those inoculated intra-cervically. The number of spermatozoa recovered from uterine horns and oviducts of intra-cervically treated does was less than that retrieved from intra-peritoneally treated animals and controls. These results suggest (i) that sub-acute or acute inflammation may cause infertility by compromising the uterine environment and/or impairing sperm transport and (ii) that the LPS-induced -infection/inflammation experimental model is useful for studying the mechanisms involved in reproductive dysfunctions in the rabbit.

Effect of dietary supplementation with olive pomaces on the performance and meat quality of growing rabbits.

The aim was to investigate the effects of three types (A, B and C) of stoned and dehydrated olive pomaces (OPs), differing in olive cultivar, on productive performance and meat quality of growing rabbits. The inclusion of OPs (5%) negatively affected the performance of rabbits as it reduced the feed intake, growth rate, carcass weight and dressing out percentage (P<0.05). Compared with the control, the meat of OP rabbits had a greater amount of monounsaturated and a lower amount of polyunsaturated fatty acids (P<0.05), independent of the type of OP used. Oxidative processes in the meat of OPA and OPB were higher (P<0.05), whereas OPC showed the same levels as the control group. This was due to the higher total polyphenol concentration and to the concomitant lower peroxide value of OPC. These results recommend the use of OP in rabbit diet with caution, taking into account the quality of the by-product in terms of oxidative status.

Secretion patterns and effect of prostate-derived granules on the sperm acrosome reaction of rabbit buck.

There is increasing evidence that the particulate fraction of seminal plasma plays an important role in reproduction of several mammalian species. However, the origin and role of these granules in the physiology of rabbit spermatozoa is partially unknown. The aim of this study was to investigate the implication of prostate gland in the production and secretion of granules into the rabbit semen and the role of prostate-derived granules in the sperm acrosome reaction. Light and electron microscopy of the prostate gland showed that the anterior and middle tracts of the prostate (namely the proprostate and prostate, respectively) are chiefly implicated in the secretion of granules of different size: smaller granules (SG; 0.5 µm) and large granules (LG; 4 µm). Two major patterns of secretion were identified, based on electron microscope views: storage granules (large granules) seem to empty inner smaller granules directly into the duct by exocytosis, or the storage vesicle itself is released in toto into the ducts (diacytosis). In vitro experiments using granules from vasectomized rabbits, to exclude testicular origin of granules, showed that granules reduce the acrosome reaction of Percoll-selected spermatozoa, independently of the size. Interestingly, spermatozoa incubated with heat-treated granules showed a higher sperm acrosome reaction rate, suggesting a potential role of granule-derived proteins in this process. Inhibition of the acrosome reaction is a crucial event in rabbit reproduction; ejaculated spermatozoa have to wait for a long time (8-16 h) for egg availability in the female tract after mating. Taking together, our results demonstrate that prostate granules secreted either by exocytosis or diacytosis can preserve spermatozoa fertilizing ability, by preventing sperm acrosome reaction. The type of granule-derived proteins or other macromolecules implicated in this process should be further investigated.

Ovulating induction methods in rabbit does: the pituitary and ovarian responses.

The aim of this study was to compare the pituitary and ovarian responses in rabbit does subjected to different methods of ovulation induction. Forty-eight receptive females were randomly distributed into six groups (N = 8) and were inseminated with standard glass catheters. Buserelin intramuscular (BM) does were inseminated using a pool of fresh heterospermic semen and an intramuscular injection of 1 µg of buserelin acetate to induce ovulation. Buserelin intravaginal (BV) does were inseminated in a similar way, but ovulation was induced with the GnRH analogue (10 µg of buserelin acetate) combined with 0.5 mL of semen extender. The raw semen (R) and saline groups (S) were inseminated with undiluted semen or saline, respectively, without any inducer of ovulation. Another group (A) received lumbar anaesthesia (1.5 mL of 2% lidocaine), and only the empty catheter was introduced into the vagina. The AR does were treated the same way as group A but were inseminated with raw semen instead of an empty catheter. Blood samples were collected to determine the LH concentrations before and after AI (30, 60, 90, and 120 minutes). Ovulation, pregnancy, and conception rates were determined after euthanasia on day 14 post AI. Ovulating does had higher mean LH concentrations than nonovulating does (197.9 vs. 45.9 ng/mL; P < 0.05). The ovulation rates of buserelin intramuscular and intravaginal does were 100%, and the pregnancy rates were 87.5% and 100%, respectively. Rabbit does in groups A and AR did not ovulate and had similar mean plasma LH concentrations after 60 minutes compared with the S group (49.4 and 49.2 ng/mL vs. 41.6 ng/mL, respectively), which reached ovulation and pregnancy rates of 37.5%. Does inseminated only with raw semen had an ovulation rate of 75% and a pregnancy rate of 62.5%; they also demonstrated higher plasma LH concentrations than does of the S, A, and AR groups. In conclusion, ovulation in rabbit does can be induced by exogenous GnRH administration (im and intravaginal). The high plasma LH concentration and ovulation rate in the R group with respect to the S and A groups could weakly indicate the presence of some molecules in the seminal plasma that could act on or be absorbed by vaginal mucosa. Sensory stimulation and "seminal factors" probably exert a synergy on the ovulation response as demonstrated by the comparison of LH release and the ovulation response in the R, S, RA, and A groups.

Effect of a bacterial lipopolysaccharide treatment on rabbit testis and ejaculated sperm.

In a previous study, we reported the short- and long-term effects of bacterial lipopolysaccharide (LPS)-induced inflammation on rabbit sperm quality. This study was aimed at exploring the spermatogenesis of the rabbit model focussing on the possible damages occurring to the testis and ejaculated sperm. Twenty New Zealand White rabbit bucks were divided into two groups. One group was inoculated intra-peritoneally with LPS, the other group, considered as control, was treated under the same conditions with saline only. Semen samples were collected before LPS injection, the 7th, 14th, 21st, 30th, 45th, 60th and 90th day after LPS treatment. Semen parameters were evaluated following international guidelines. The kinetic characteristics of ejaculated sperm were analysed using a computer-assisted sperm analyzer and the ultrastructural characteristics were explored by transmission electron microscopy (TEM). On the 7th, 14th and 30th day, testis from treated rabbits and controls were obtained. Testis samples were analysed by light microscopy and TEM. The induced LPS lesions in the testis became evident the 7th day after treatment, with a decrease in germinal cells and with an increase in structurally altered Sertoli cells; normal spermatogenesis was restored on the 30th day. The testicular damages observed on day 7 were probably responsible for the reduction in sperm concentration and motility and the ultrastructural alterations that were detected in the ejaculated sperm on the 14th through the 30th days after treatment. In conclusion, rabbit buck treated with LPS could be a useful model for studying the effect of an induced systemic inflammation on spermatogenesis.

Short- and long-term effects of lipopolysaccharide-induced inflammation on rabbit sperm quality.

Infections and resulting inflammation are widely known to cause transient or permanent male infertility. The objectives of this study were (1) to provide a suitable animal model of a sub-acute inflammatory state by intraperitoneally inoculating bacterial lipopolysaccharides (LPS) and (2) to define the short- and long-term effects of this state on the sperm quality of rabbit bucks. Two series of experiments were performed to accomplish these objectives. In experiment 1, 15 healthy New Zealand White rabbit bucks were divided into five homogeneous groups, receiving 25, 50, 100 and 150 microg/kg body weight (b.w.) of E. coli LPS dissolved in 2ml of sterile saline or only saline (control), respectively. White blood cells (WBC), rectal temperature, feed intake and mating ability were observed for 3 consecutive days following inoculation. Inoculation of 50 microg/kg b.w. produces a reversible inflammation-like state that lasts for about 3 days, with minimal distress to the animals, and therefore it was used in our experiment. The major symptoms were fever and anorexia. Changes in WBC count and a moderate reduction in reproductive activity also occurred. In experiment 2, two groups of five rabbit bucks each were treated with 50 microg/kg b.w. E. coli LPS diluted in 2ml of saline or only saline (controls), respectively. Semen samples were collected weekly up to 56 days after inoculation and the changes in semen characteristics were examined. During the first 3 days, semen volume and concentration decreased in both experimental groups, probably due to the high collection frequency. Sperm membrane integrity and the number of necrotic sperm were seriously affected 30 days after the LPS challenge, reaching a maximum at the end of the spermatogenic cycle (56 days). These results suggest that a sub-acute inflammation may cause infertility by compromising sperm membrane integrity which decreases a month after LPS-treatment. In addition, the rabbit could be a useful LPS animal model for further study of the effects of inflammation and the underlying mechanisms on sperm characteristics.

Effects of flaxseed dietary supplementation on sperm quality and on lipid composition of sperm subfractions and prostatic granules in rabbit.

Lipids are the main structural/functional components of the sperm, and their composition may undergo a series of modifications in relation to either physiologic events (capacitation and acrosome reaction) and/or diet. The goals of the current study were (1) to investigate whether a flaxseed (FS) dietary supplementation could affect the lipid and fatty acid profile of sperm subfractions and of prostatic granules (PGs) and (2) to evaluate the effects of dietary FS on rabbit buck semen quality. Accordingly, 20 adult New Zealand White rabbits were fed ad libitum a control diet (CO) or a diet supplemented with 5% extruded FS. Integration of diet with FS, as a consequence of the linolenic acid (C18:3n-3; LNA; 56%), increased the dietary n-3/n-6 ratio and resulted in a substantial rearrangement of sperm fatty acid composition at the subcellular level, mainly of polyunsaturated fatty acid (PUFA)n-3 (8.3% vs. 14.3%, P<0.05). The lipid and fatty acid profiles of sperm tail membrane were the most affected, undergoing the following significant changes: (1) a reduction by half of linoleic acid (C18:2n-6; LA) and docosapentaenoic acid (22:5n-6; DPA), and a reduction of cholesterol (-70%); (2) a concomitant increase of LNA (+65%), docosahexaenoic acid (22:6n-3; DHA; +83%), and of oleic acid (C18:1n-9, +61%). As a consequence, the sperm of FS-fed rabbits had a twice higher n-3/n-6 ratio and phospholipid/cholesterol ratio compared with the control sperm. These changes might have been on the basis of the higher responsiveness to hypo-osmotic solution and, hence, the higher sperm track speed observed for the FS group. Also, the membrane integrity and viability of the LNA-enriched sperm were both improved. On the other hand, the presence of lignans in FS might have accounted for the reduction of sperm cholesterol in the semen of FS-treated rabbits. The responsiveness of sperm to acrosome reaction was not affected by the dietary treatment probably due to supranutritional level of vitamin E and to the higher number of PGs, which are known to play a key role in sperm capacitation. In conclusion, our data showed for the first time that the integration of FS into the rabbit diet may improve sperm quality by modifying the sperm lipid composition and that the sperm subfractions and the PGs respond differently to the FS-induced lipid manipulation.

Computer hazards: real or imaginary?

Extensive use of video display terminals (VDTs) and reports of suspected adverse health effects attributed to their operation have increased operator concern and interest. Information to assist supervisors and health personnel in responding to health-related questions and in evaluating the workplace for dangers concerning VDTs is provided.