Influence of vitamin A injection before mating on oocyte development, follicular hormones, and ovulation in gilts fed high-energy diets.

Previous research revealed that treatment with vitamin A approximately 5 d before ovulation may increase litter size in weaned sows and improve embryonal survival in gilts fed high-energy diets that reduced embryonal survival. For the current study, the hypothesis was that administration of vitamin A before ovulation would alter development of follicles and oocytes in a way favorable to enhanced embryonal survival. (Landrace x Large White) x (Duroc x Hampshire) gilts (n = 44) were fed 11.0 Mcal ME x gilt(-1) x d(-1) beginning 7 d after second estrus and given (i.m.) corn oil or 1 x 10(6) IU of vitamin A (retinyl palmitate) on d 15 after second estrus. Gilts were checked for estrus every 4 h, mated naturally at third estrus, and assigned randomly to undergo midventral laparotomy beginning at 24 to 28, 28 to 32, 32 to 36, or 36 to 40 h after onset of third estrus. At laparotomy, ovulated oocytes and early-stage embryos were recovered from oviducts, and ovaries were removed for aspiration of oocytes and granulosa cells from unovulated follicles. Oocytes and embryos were stained for assessment of stage of development. Granulosa cells were cultured to assess their ability to secrete progesterone. Follicular fluid was assayed for progesterone, estradiol-17beta, IGF-I, and PGF2alpha. Treatment with vitamin A altered development of oocytes and embryos by decreasing the percentage at the germinal vesicle stage and increasing the percentage at advanced stages. Mean stage of development was increased by vitamin A, but variation in stage was decreased. Among follicles matched by meiotic stage of oocyte, follicular fluid concentrations of progesterone, IGF-I, and PGF2alpha were greater in vitamin A-treated gilts than in controls, but treatment with vitamin A in vivo did not affect LH-stimulated or unstimulated secretion of progesterone by granulosa cells in vitro. These data provide evidence that vitamin A may influence embryonic development by advancing resumption of meiosis and altering follicular hormonal environment during follicle maturation.

Evidence that injection of vitamin A before mating may improve embryo survival in gilts fed normal or high-energy diets.

The hypothesis was that administration of vitamin A before ovulation would improve embryo survival in gilts fed a high-energy diet intentionally to reduce embryo survival. Forty crossbred ([Landrace x Large White] x [Duroc x Hampshire]) gilts were fed control (5.5 Mcal ME/d) or high-energy (11.0 Mcal ME/d) diets from 7 d after second estrus until 11 to 12 d after third estrus. Gilts in each dietary group received (i.m.) corn oil or retinyl palmitate (1 x 10(6) IU, vitamin A) on d 15 after second estrus and were mated at third estrus. Blood for determination of progesterone and estradiol was collected twice daily. The uterus and ovaries were removed on d 11 or 12 after third estrus for assessment of number of CL, and number, size and aromatase activity of embryos. Neither diet nor vitamin treatment affected number of CL. The high-energy diet exerted a negative effect on number of embryos (P = .09) and embryo survival (P = .07), whereas vitamin A exerted a positive effect on number of embryos (P = .07) and embryo survival (P = .08). The high-energy diet increased variation in embryo diameter, whereas vitamin A reduced variation in diameter and increased average diameter. Neither diet nor vitamin treatment influenced aromatase activity of embryos. Diet and vitamin treatment interacted with day to influence serum progesterone, but not estradiol. Injecting vitamin A before estrus restored embryo survival to normal levels in gilts fed high-energy diets, and this may be attributable to decreased variation in size of embryos.

In vivo metabolism of nasally instilled benzo[a]pyrene in dogs and monkeys.

Metabolism of inhaled materials deposited in the nasal cavity potentially influences their biological fate and toxicity. Metabolic enzymes, including cytochrome P-450-dependent monooxygenases, are not evenly distributed throughout the nasal cavity. The purpose of this study was to determine whether benzo[a]pyrene (BaP) deposited in the nasal cavity could be metabolized and cleared by the nasal tissue in the ethmoid and maxillary turbinate regions of Beagle dogs and cynomolgus monkeys. Nasopharyngeal mucus was collected at frequent intervals during periodic nasal instillations of BaP (and for dogs 24 h after instillation) for analysis of BaP and its metabolites. During and up to 48 h after nasal instillation of [14C]BaP, blood, urine and feces were collected to determine BaP clearance from the nose. High pressure liquid chromatographic analysis of organic phase extracts of nasopharyngeal mucus demonstrated that [14C]BaP instilled in either turbinate region was metabolized to dihydrodiols, quinones, phenols and tetrols in both species. Phenols were the major metabolic product, although all treated animals produced trans-7,8-dihydrobenzo[a]pyrene-7,8-diol. The dog mucus sampled at 24 h had no detectable radioactivity. The excreta from both species contained only small amounts of the instilled radioactivity. There was no distinctive pattern of metabolite production based on instillation site.

Technique for aerosol deposition restricted to the nose in beagle dogs.

A method was developed for exposing the nasal cavity of beagle dogs to a radiolabeled aerosol without exposure of the remainder of the respiratory tract. Deposition efficiency, using a test aerosol of 2.0-micron particles of 99mTc-sulfur colloid delivered to the nose, was 15 +/- 2% (mean +/- SE) of inhaled activity. Gamma camera imaging showed that maximum deposition occurred in the anterior third of the nasal cavity, which contained 78 +/- 4% (mean +/- SE) of the total deposited radioactivity. The middle-third of the nasal cavity received 13 +/- 3% and the posterior third 9 +/- 2% of the deposited radioactivity. Aerosol deposition in regions of the respiratory tract below the larynx was not detectable.

Effect of aging on tracheal mucociliary clearance in beagle dogs.

Tracheal mucous velocity measurements were made in 24 beagle dogs in five age groups, using a gamma camera to detect movement of instilled 99mTc-macroaggregated albumin. Age groups were defined as immature (9-10 mo), young adult (2.8-3.0 yr), middle aged (6.7-6.9 yr), mature (9.6-9.8 yr), and aged dogs (13.6-16.2 yr). Mean velocities were 3.6 +/- 0.4 (SE) mm/min in the immature dogs, 9.7 +/- 0.6 mm/min in the young adults, 6.9 +/- 0.5 mm/min in the middle-aged dogs, 3.5 +/- 0.8 mm/min in the mature dogs, and 2.9 +/- 0.5 mm/min in the aged dogs. Tracheal mucous velocity was significantly (P less than 0.05) greater in the young adult and middle-aged groups compared with the immature, mature, and aged dogs. This pattern of age-related changes was noted to be similar to age-related changes described for certain pulmonary function measurements.

Clearance of nasal mucus in nonanesthetized and anesthetized dogs.

Clearance rates for nasal mucus in the maxillary turbinate region were measured in 8 Beagle dogs. 99mTc Macroaggregated albumin (10 microliters) was instilled in the nasal maxillary region of dogs under general anesthesia. A gamma camera was used to detect movement of the 99mTc macroaggregated albumin in the nose for 1 hour after it was instilled. Velocity of mucus was measured in the 8 dogs each under 3 conditions of anesthesia: anesthesia with pentobarbital given IV (20 mg/kg of body weight), anesthesia with halothane gas, and no anesthesia. Mean velocities (+/- SD) were 3.7 +/- 1.4 mm/min in dogs anesthetized with pentobarbital, 4.3 +/- 2.5 mm/min in dogs anesthetized with halothane, and 3.4 +/- 1.7 mm/min in awake dogs. The differences between the 3 anesthetic conditions were not significant at the P less than 0.05 level. Use of anesthesia at a light surgical plane provides a controlled method for measurement of clearance of nasal mucus with minimal alterations from the nonanesthetized state.

In vivo metabolism of nasally instilled dihydrosafrole [1-(3,4-methylenedioxyphenyl)propane] in dogs and monkeys.

Nasal metabolism of inhaled material may influence its biological fate and toxicity. The purpose of this study was to investigate, in a noninvasive and qualitative manner, the in vivo nasal metabolic activity towards 1-(3,4-methylenedioxyphenyl)propane (dihydrosafrole). Dihydrosafrole was the compound of choice as a representative of the methylenedioxyphenyl compounds. Methylenedioxyphenyl compounds, inhaled as essences or insecticide synergists, have complex interactions with cytochrome P-450-dependent monooxygenases, causing both inhibition and induction. Clearance of dihydrosafrole and its metabolites from both the ethmoid (olfactory) and maxillary (respiratory) turbinate regions of Beagle dogs and Cynomolgus monkeys was examined. Nasopharyngeal mucus was collected at frequent intervals during periodic instillation of dihydrosafrole (and, for the dogs, 24 h after instillation). Blood, urine and feces were collected to examine dihydrosafrole clearance from the nose during instillations and up to 48 h after completion of the nasal instillations of [3H]dihydrosafrole. Analysis of mucus for dihydrosafrole metabolites was by HPLC. Most of the recovered radioactivity was in urine and blood samples over the first 24 h. Radioactivity was recovered from the nasopharyngeal mucus in both organic extractable and water soluble forms. HPLC of the organic extracts demonstrated that [3H]dihydrosafrole instilled in either turbinate region was metabolized to 2-methoxy-4-propylphenol, 2-methoxy-4-propenylphenol and 1-(3,4-methylenedioxyphenyl)propan-1-ol. A number of minor metabolites were produced in both species. One mucus sample from an ethmoid-instilled dog contained 1-(3,4-methylenedioxyphenyl)propene (isosafrole) as a metabolite. Results from this study indicate that interspecies, inter-individual, and inter-regional differences occur in the metabolism of nasally deposited dihydrosafrole in monkeys and dogs.

Mucociliary clearance and particle retention in the maxillary and ethmoid turbinate regions of beagle dogs.

In this study, the retention and clearance of particles instilled onto the epithelium at two sites in the nasal cavity were examined. Polystyrene microspheres (3 micron geometric diameter) were labeled with 141Ce or 85Sr and instilled simultaneously on the maxillary and ethmoid turbinates of beagle dogs. The retention and clearance patterns of the microspheres were followed for 30 d after instillation. Tissue samples, excreta content, and autoradiography of the radiolabels provided the basis for defining the fate of the microspheres or the radiolabels dissolved from the microspheres. Early nasal mucus velocity was significantly faster (p less than 0.05) from the maxillary turbinate region (2.5 +/- 0.7 mm/min, mean +/- SE) than from the ethmoid turbinate region (0.6 +/- 0.4 mm/min). Retention at both instillation sites at 30 d after instillation was approximately 0.1% of the amount initially instilled. Radioactivity was excreted primarily via the feces during the first few days. Radiolabel measured in urine and tissues other than turbinates was small (less than 0.05% of the initial burden), indicating minimal dissolution of the radiolabel from the particles. Autoradiographs of turbinate tissue revealed particles sporadically located in the epithelial submucosa. From these data, it was concluded that a significant difference in early clearance for particles exists between the ethmoid and maxillary turbinates, but there was no difference in the fraction of particles retained in these two areas for long periods of time.