Effects of cobalt on postnatal development and late gestation in rats upon oral administration

Four groups of pregnant Wistar rats, each of which consisted of 15 animals were administered 0, 12, 14 and 48 mg/kg/day of cobalt (II) chloride from the 14th day of gestation through 21 days of lactation. The offspring were observed for mortality, body weight, body and tail length and general symptomatology after 1, 4 and 21 days of nursing. The number of litters was higher for the control group. The survival ratios were also higher for the control group. Besides, a dose-dependent delay in the growth of the living young could be observed. No significant differences in organ weights in the animals killed 21 days after birth were observed. The blood parameters analysed did not show differences between the treated and control pups. Cobalt produced toxic effects on the mothers, affecting the late gestation as well as the postnatal development of the pups.     

Effects of gestation and lactation on rat gastric fundus

This study evaluated the effects of gestation and lactation on stomach growth in rats. Constant increases were observed in gastric fundus weight during pregnancy and lactation, with a maximum obtained after 3 weeks of lactation. This increase in tissue weight was not associated with hyperplasia of the gastric fundus as in no instance did total DNA contents from mated females differ significantly from those of the unmated controls. Mild hypertrophy, as evidenced by significant increases in cellular mass and RNA and protein concentrations, was observed during late lactation. Gastrin might be responsible for these modest changes in the gastric fundus.     

Embryotoxic and teratogenic effects of aluminum nitrate in rats upon oral administration

In order to determine the embryotoxic and teratogenic potential of aluminum, pregnant Sprague-Dawley rats were treated by gavage with a daily dose of 180, 360, or 720 mg/kg of aluminum nitrate from the sixth through to the fourteenth day of gestation. Fetal examinations were performed on day 20. The number of corpora lutea, total implants, and resorptions as well as the number of live and dead fetuses in the treated animals were not significantly different from the control group. Therefore, embryolethality of aluminum cannot be induced (as a measure of percent dead and resorbed fetuses). However, exposure of rats to aluminum nitrate resulted in decreased fetal body weight and increased the incidence and types of external, visceral, and skeletal malformations and variations in all the treated groups. Consequently, teratogenic effects of aluminum-nitrate administration may result in rats given high oral doses that induce concomitant maternal toxicity.     

Effects of dietary menhaden oil on growth and reproduction in gilts farrowed by sows that consumed diets containing menhaden oil during gestation and lactation

In sows, n-3 fatty acids increase litter sizes, however, effects on gilt reproductive development have not been adequately studied. Moreover, not determined are effects of feeding n-3 fatty acids to sows on reproduction in offspring. The objective here was to determine effects of 4% dietary menhaden oil on growth and puberty in gilts farrowed by sows fed menhaden oil. Sows (n = 44) were assigned to: (1) control gestation and lactation diets, or (2) diets including menhaden oil. For primiparous sows only, total litter size and born alive were greater (P < 0.05) in females fed menhaden oil. Conversely, pigs from primiparous controls were heavier (P < 0.05) than pigs from primiparous sows fed menhaden oil (parity by diet interactions, P < 0.01). Diet did not affect (P > 0.20) other sow and litter characteristics. At weaning, 84 gilts from control- or menhaden oil sows were placed three gilts per pen and provided control diets or diets containing menhaden oil. Nursery and grow-finish feed intake and feed efficiency were similar (P > 0.21) for gilts from the different sows and weight gain was similar (P > 0.24) for gilts fed control or menhaden diets. Gilts fed menhaden oil tended to eat less in the nursery (1.18±0.08 kg v. 0.98±0.08 kg; P = 0.09) and overall (1.83±0.04 kg v. 1.72±0.04 kg; P = 0.06). Thus, overall feed to gain was greater (2.52±0.03 v. 2.33±0.03; P < 0.01) and nursery (2.12±0.04 v. 1.80±0.04; P = 0.10) and grow-finish (3.07±0.19 v. 2.58±0.19; P = 0.08) feed to gain tended to be greater, for control gilts. Age at puberty was greater (P = 0.02) for gilts from menhaden oil-fed sows (205.1±3.2 days) compared to gilts from controls (193.9±3.2 days) and tended to be greater (P = 0.09), for controls (203.5±3.2 days) compared to gilts fed menhaden oil (195.5±3.2 days). A tendency existed (P = 0.09) for greater follicular fluid in gilts fed menhaden oil, however, ovulation rate and ovarian, luteal and uterine weights were not affected by sow diet, gilt diet or the interaction (P > 0.23). Feeding gilts menhaden oil enhanced feed efficiency and hastened puberty onset. Gilts from sows consuming menhaden oil exhibited delayed puberty and retaining females from sows fed this feedstuff may be ill advised.     

Effects of concurrent pregnancy and lactation on reproduction in four strains of mice

The influence of concurrent pregnancy until the third lactation on reproduction was studied in four strains of mice (SHN, SLN, C3H/He and GRS/A) as a possible step to evaluate the efficiency of this system on offspring production. In all strains, little difference was observed between sequential and concurrent pregnancy and lactation groups in any parameter as the index of reproductivity--delivery interval, litter size, average weight and growth rate of pups, mother weight, rearing rate, still-birth rate and rate of still-born pups. Also, no difference was seen between groups of any strain, in the number of females which had three litters. The estimated number of pups weaned per female during 50 days after first being placed with males was higher in the concurrent pregnancy groups than in the sequential pregnancy groups of all strains. Meanwhile, the incidence of spontaneous mammary tumors, the major characteristic of these strains, was consistently lower in the concurrent pregnancy group in all strains. These results have demonstrated that the concurrent pregnancy and lactation system is an efficient means of mouse production.     

Effects of oral administration of benzylamine on glucose tolerance and lipid metabolism in rats

Repeated administration of benzylamine plus vanadate have been reported to exhibit anti-hyperglycemic effects in different models of diabetic rats. Likewise oral treatment withMoringa oleifera extracts which contain the alkaloïd moringine, identical to benzylamine, has also been shown to prevent hyperglycemia in alloxan-induced diabetic rats. With these observations we tested whether prolonged oral administration of benzylamine could interact with glucose and/or lipid metabolism. Seven week old male Wistar rats were treated for seven weeks with benzylamine 2.9 g/l in drinking water and were submitted to glucose tolerance tests. A slight decrease in water consumption was observed in benzylamine-treated animals while there was no change in body and adipose tissue weights at the end of treatment. Blood glucose and plasma insulin, triacylglycerol or cholesterol levels were not modified. However, benzylamine treatment resulted in a decrease in plasma free fatty acids in both fed and fasted conditions. Benzylamine treatment improved glucose tolerance as shown by the reduction of hyperglycemic response to intra-peritoneal glucose load. Oral benzylamine treatment did not alter the response of adipocytes to insulin nor to insulin-like actions of benzylamine plus vanadate, viain vitro activation of glucose transport or inhibition of lipolysis. This work demonstrates for the first time that oral administration of benzylamine alone influences glucose and lipid metabolism. However, these results obtained in normoglycemic rats require to be confirmed in diabetic models.     

Effects of anandamide on gestation in pregnant rats

The present study was to test whether the recently described endogenous ligand for the cannabinoid receptor; arachidonyl-ethanolamide (anandamide, ANA), may produce similar effects on pregnancy as the main psychoactive component of marihuana: Δ⁹-tetrahydrocannabinol (THC) in rats. ANA, THC (0.02 mg/kg i.p./day, respectively) or vehicle were injected daily over the third week of pregnancy. The pregnant rats were either killed on day 21 of pregnancy or followed up to delivery. Results show a significant increase in the duration of pregnancy after both THC and ANA treatment. Both drugs caused an increase in the frequency of stillbirths. The mothers' hormone contents in tissues and sera were measured. Decreased LH content was observed in the serum of treated animals. No changes in FSH content were observed either in the pituitary or in the sera. Pituitary prolactin (PRL) levels was lower in ANA treated animals as compared both to controls or THC treated subjects. The serum PRL content decreased in all experimental groups. Decrease in serum progesterone was more prominent in treated rats. Serum levels of prostaglandins (PGF 1 and PGF 2) were significantly decreased after THC and ANA treatment. We conclude that ANA has the same tendency to change reproductory parameters in pregnant rats as THC, although in some cases the effects of ANA were slightly different from that of THC. Both endogenous and exogenous cannabinoids inhibit PG synthesis in pregnant rats and this maybe responsible for the delay constitute the mechanism in the onset of labour.     

Effect of high-fat diet during gestation, lactation, or postweaning on physiological and behavioral indexes in borderline hypertensive rats

Maternal obesity is becoming more prevalent. We used borderline hypertensive rats (BHR) to investigate whether a high-fat diet at different stages of development has adverse programming consequences on metabolic parameters and blood pressure. Wistar dams were fed a high- or low-fat diet for 6 wk before mating with spontaneously hypertensive males and during the ensuing pregnancy. At birth, litters were fostered to a dam from the same diet group as during gestation or to the alternate diet condition. Female offspring were weaned on either control or "junk food" diets until about 6 mo of age. Rats fed the high-fat junk food diet were hyperphagic relative to their chow-fed controls. The junk food-fed rats were significantly heavier and had greater fat pad mass than those rats maintained on chow alone. Importantly, those rats suckled by high-fat dams had heavier fat pads than those suckled by control diet dams. Fasting serum leptin and insulin levels differed as a function of the gestational, lactational, and postweaning diet histories. Rats gestated in, or suckled by high-fat dams, or maintained on the junk food diet were hyperleptinemic compared with their respective controls. Indirect blood pressure did not differ as a function of postweaning diet, but rats gestated in the high-fat dams had lower mean arterial blood pressures than those gestated in the control diet dams. The postweaning dietary history affected food-motivated behavior; junk food-fed rats earned less food pellets on fixed (FR) and progressive (PR) ratio cost schedules than chow-fed controls. In conclusion, the effects of maternal high-fat diet during gestation or lactation were mostly small and transient. The postweaning effects of junk food diet were evident on the majority of the parameters measured, including body weight, fat pad mass, serum leptin and insulin levels, and operant performance.     

Effects of endocrine disruptors on reproduction in viviparous teleosts with intraluminal gestation

Many water systems worldwide are affected by pollutants, including potential endocrine disruptors (EDs). Most studies on the effects of EDs on fish reproduction have focused on oviparous species. However, some important groups of fishes are not oviparous and there is scarce information about how EDs affect species with alternative reproductive modes. Goodeinae is a viviparous matrotrophic subfamily with intraluminal gestation (IG), where transfer of nutrients occurs and embryos develop inside the ovarian cavity. Goodeinae is endemic to the Mexican Central Plateau, an area affected by potential EDs, including 2,4-dichlorophenoxyacetic acid (2,4-D). This review synthesizes the available information about EDs in viviparous teleosts with IG and performs a case study on the effects of 2,4-D on gonadal structure of two Goodeinae species. We hypothesized that individuals exposed to 2,4-D might show altered gonadal structure. The available information included effects on gene expression, sexual differentiation, gametogenesis, secondary sexual characteristics, and sexual behavior. Knowledge gaps persisted on the effects of EDs on viviparous teleosts with IG. Holistic approaches are needed to understand the mechanisms underlying endocrine disruption effects. Field studies are needed to evaluate the consequences of EDs on wild populations. The case study revealed histological alterations in oocytes, spermatogonia, and sperm cysts in fishes exposed to 2,4-D. Ultrastructurally, gonads exhibited alterations in oocyte mitochondrial and nuclear membranes, and in spermatid mitochondria. The observed changes could be related to 2,4-D exposure, which may affect species reproduction in their natural environment. Matrotrophic viviparous teleosts with IG may serve as models to explore endocrine disruption.     

Effects of hypothalamic deafferentation late in gestation on lactation and nursing behavior in the rat

Complete deafferentation of the medial basal hypothalamus (MBH) in 13 primiparous Sprague-Dawley rats was performed on or about Day 14 of gestation. The most significant result was a depression in litter growth as evidenced by the marked number of dead pups by the postpartal Day 5 and the loss of weight in those that survived. Control animals deafferented in the same region but only along one side (the incomplete deafferented rats, n = 9) adequately maintained young. Animals in both groups gave birth as expected. There were no significant differences in the latency and duration of retrieving and crouching behaviors. Therefore, nursing behavior appeared normal. Only milk ejection seemed disturbed, judging from the fact that suckling alone could not release milk, oxytocin in addition was needed. Thus, by the methods we employed, the MBH appears to be necessary for lactation but not for nursing behavior in the primiparous rat.     

Effects of rapid weight gain to puberty on reproduction, mammary development and lactation in ewe lambs

The effects of rapid weight gain to puberty on reproduction, mammary development and milk production in ewes lambing at 13 mo of age were investigated on three trials. A total of 64 Dorset and 93 Suffolk ewe lambs were weaned at 42 d of age and their mean weight was 16 kg. These ewes were assigned, within breed groups, to either a finishing diet or a growing diet. Onset of puberty was determined by daily checks for estrus and ewes were bred beginning at 7 mo of age. In Trial 2, mammary gland development was determined in eight Suffolk ewes from each diet. Ewes on the finishing diet were younger at puberty than those on the growing diet (199 vs 206 d, P<0.05) but required more services per conception (1.3 vs 1.1, P<0.05). Dietary conception rate and lambing rate means were similar. Mean 4-h milk yield was lower (P<0.10) for ewes on the finishing diet (283 g) than for those on the growing diet (310 g). Mammary gland fat pad area was higher (P<0.05) for ewes on the finishing diet compared with those fed for growth. Gross and adjusted duct areas were higher in ewes on the growing diet, but differences were not significant. At puberty, negative correlation coefficients for milk yield with performance traits were as follows: daily weight gain, -0.184 (P<0.08); weight-to-height ratio -0.262 (P<0.01); body condition score, -0.189 (P<0.07); and body weight, -0.212 (P<0.05). Results of this study indicate that rapid weight gain to puberty impairs mammary gland development and milk production in ewe lambs.