A novel NADP(+)-dependent dehydrogenase activity for 7alpha/beta- and 11beta-hydroxysteroids in human liver nuclei: A third 11beta-hydroxysteroid dehydrogenase.

Human tissue from uninvolved liver of cancer patients was fractionated using differential centrifugation and characterized for 11betaHSD enzyme activity against corticosterone, dehydrocorticosterone, 7alpha- and 7beta-hydroxy-dehydroepiandrosterone, and 7-oxo-dehydroepiandrosterone. An enzyme activity was observed in nuclear protein fractions that utilized either NADP(+) or NAD(+), but not NADPH and NADH, as pyridine nucleotide cofactor with K(m) values of 12+/-2 and 390+/-2microM, compared to the K(m) for microsomal 11betaHSD1 of 43+/-8 and 264+/-24microM, respectively. The K(m) for corticosterone in the NADP(+)-dependent nuclear oxidation reaction was 102+/-16nM, compared to 4.3+/-0.8microM for 11betaHSD1. The K(cat) values for nuclear activity with NADP(+) was 1687nmol/min/mg/micromol, compared to 755nmol/min/mg/micromol for microsomal 11betaHSD1 activity. Inhibitors of 11betaHSD1 decreased both nuclear and microsomal enzyme activities, suggesting that the nuclear activity may be due to an enzyme similar to 11betaHSD Type 1 and 2.

Corticosterone oxidative neutralization by 11-beta hydroxysteroid dehydrogenases in kidney and colon of the domestic fowl.

In mammalian organs involved in sodium reabsorption, the 11-beta hydroxysteroid dehydrogenases (11betaHSDs) oxidize glucocorticoids (GC) from their 11-alcohol form to their 11-keto state and therefore prevent their binding to mineralocorticoid (MC) receptors (MR) and the development of a MC excess syndrome. In birds the information about 11betaHSDs and GC metabolism in such organs is scarce. Herein, we report the expression and enzymatic activity of 11betaHSDs in the kidney and colon of chickens. Both organs express 11betaHSD2-like mRNA. With NAD(+), microsomes from both tissues oxidized corticosterone (CS) into 11-dehydrocorticosterone (DHC) with K(m) of 200 and 20nM and V(max) of 13 and 2pmol/mg protein/min in the kidney and colon, respectively. Thiram, a specific 11betaHSD2 inhibitor, suppressed this oxidation in kidney. The expression and action of the putative 11betaHSD3 were also tested. The chicken colon, and to a greater extent the kidney, expressed 11betaHSD3-like mRNA. Microsomal fractions from both tissues oxidized CS into DHC in the presence of NADP(+) with K(m) of 150 and 4nM and V(max) of 5 and 0.3pmol/mg protein/min for the kidney and the colon, respectively. This oxidation was not affected when NADP(+) conversion into NAD(+) was inhibited by excess pyrophosphate or a phosphatase inhibitor cocktail. In microsomes of chicken's duodenum, where 11betaHSD1-like mRNA expression is high, NADP(+)-dependent oxidation of CS into DHC has a low-affinity K(m) of 1130nM. This study documented the expression and activity of two enzymes that convert CS into DHC, one is 11betaHSD2-like and the other is similar to the putative mammalian 11betaHSD3.

Distinct features of dehydrocorticosterone reduction into corticosterone in the liver and duodenum of the domestic fowl (Gallus gallus domesticus).

The mammalian 11-beta hydroxysteroid dehydrogenase type 1 (11 betaHSD1) reduces glucocorticoids (GC) at C11 from the 11-keto-GC nonactive form to the 11-hydroxy-GC active form, an action essential for survival. Whereas GC metabolism at C11 and the role of 11 betaHSD1 are studied extensively in mammals, information about these in birds is scattered. Herein, we report the GC bidirectional metabolism in chickens. In hens' liver and duodenal mucosa, 11 betaHSD1-like mRNA expression was detected; and 11 betaHSD1-like immunoreactivity was found linked to membranes of hepatocytes and duodenal enterocytes. With either NADH or NADPH, the membranal fraction of liver and duodenal mucosa converted dehydrocorticosterone (A) into corticosterone (B) with K(m) (1.1-8.7 microM) and V(max) (10-40 pmol/mg protein/min) values similar to those reported for mammalian 11 betaHSD1. In the presence of NADP(+) or NAD(+), these membranal fractions oxidized B into A. With either NADPH or NADH, the cytosol of chicken liver and duodenal mucosa reduced A into B (K(m) of 1.1 - 2.3 microM and V(max) of 260-960 pmol/mg protein/min). These cytosolic fractions did not convert any amount of B into A when incubated with either NADP(+) or NAD(+). This may suggest that chicken liver and duodenal mucosa express 11 betaHSD1 that is a membrane-bound oxoreductase which uses both NADPH/NADP(+) and NADH/NAD(+) as cosubstrates. The substantial reduction of A into B (but no conversion of B into A) found in the cytosol is most likely executed by a unidirectional soluble reductase, different than 11 betaHSD1.

Effect of hypothalamic electrolytic lesions in White Leghorn and broiler male cockerels.

1. This study compared the effect of bilateral electrolytic lesions of the basomedial hypothalamus (HL) in broiler and White Leghorn (WL) males. 2. Hypothalamic lesions were placed in WL at 10 weeks of age (body weight 1.1 kg) and in broilers, either at 6 weeks (body weight 1.5kg) or at 10 weeks of age (body weight 3.4kg). They were fed ad libitum until autopsy at 16 and 17 weeks of age for broilers and WL, respectively. 3. Hypothalamic lesions caused obesity (high percentage weight of abdominal adipose tissue) in both strains. Obese fowls with unimpaired reproductive systems were classified as OB and those with functional castration as FC (functionally castrated) or FCLC (functionally castrated with large comb). 4. All post-HL syndromes-OB, FC and FCLC-were present in WL, whereas all obese broilers (which are immature at this age) were classified as OB. 5. The percentage weight of abdominal adipose tissue in OB broilers was lower than in OB WL (3% vs 5%, respectively). 6. Daily food intake of OB broilers was higher than control at 12 to 15 weeks of age, regardless of time of placement of HL, whereas daily food intake of OB WL was significantly higher than that of control WL only during the first 2 weeks following HL. 7. Body weight of OB broilers at autopsy was 20% higher than control broilers, whereas body weight of OB WL was not significantly affected. 8. An additional group of broilers was reared to sexual maturity under food restriction until 28 weeks of age. HL were placed at 10 weeks of age (body weight 1.7 kg). Autopsy was performed after a 4-week period of ad libitum feeding. 9. There were OB as well as FC and FCLC among the HL, food-restricted broilers. Percentage weight of testes and spleen were reduced in OB fowls of both strains, but more so in OB WL. 10. Hyperphagia and weight gain were not observed during the ad libitum feeding period of those obese broilers after HL, indicating that hyperphagia and weight gain are secondary to obesity.

Reproductive traits in the spur-thighed tortoise (Testudo graeca terrestris): new tools for the enhancement of reproductive success and survivorship.

The Mediterranean tortoise (Testudo graeca) is listed as "Vulnerable" on the IUCN Red List. Reproductive characteristics and means to increase offspring production were studied in T. graeca terrestris in a semi-natural environment. Courtship and mating occurred during early spring for about 4 weeks, followed by a laying season of approximately 2 months, with a second, shorter mating period in the fall. During the first mating, calcified eggs were already present in the uterus; we inferred that sperm from both mating seasons were stored in the oviduct for fertilization of eggs of the second laying cycle and of the following year. Average egg production was 3.8+/-0.3 eggs/year. Most females laid all of their eggs in a single clutch, but 18% laid in a second clutch, 11-21 days later. X-ray radiography revealed calcified eggs in the uterus about 4 weeks before oviposition. All eggs in the uterus were calcified simultaneously and were laid in a single clutch; if a second clutch developed, those eggs were also calcified simultaneously. Based on endoscopic examinations, ovaries were active throughout the entire year. Plasma progesterone concentrations in females were very low and were detected only soon after oviposition ( 440 +/-141 pg/ml). Plasma estradiol concentrations in females varied from 4.1 +/-1.5 pg/ml to 70.2 +/-29.4 pg/ml, with no clear seasonal pattern. Maintaining tortoises at a low environmental temperature (9 +/-1 degrees C versus 28 +/- 1 degrees C) reduced plasma estradiol concentrations. Giving 2mg/kg tamoxifen (TAM) increased plasma estradiol to 220 +/-33 pg/ml when treatment was given in September but not in late October, winter or spring. Treatment with TAM increased the number of eggs laid during the following laying season to 7.3 +/- 1.0 eggs/year, laid in one to three clutches. In males, plasma testosterone concentrations had a seasonal pattern with the onset of a rise in July from 2 to >4ng/ml, a continued increase to a peak of 12.8+/-5.3 ng/ml during November and a decline thereafter. Artificial incubation in sand at 29 +/-1 degrees C shortened the natural incubation time of 103+/-3.1 days to 83.5 +/- 1.3 days, increased hatching rate from 28 to 53%, and increased survival rate from 51 to 71% at 40 weeks of age. In summary, this study provides options for increasing reproductive performance, hatchability and offspring survival in captive Mediterranean tortoises, and may offer new tools for conservation of animals that are on the verge of extinction.

Glucocorticoid administration during incubation: embryo mortality and posthatch growth in chickens.

The effects of glucocorticoids (GC) on embryonic mortality and posthatch BW were studied. Cortisol hemisuccinate or corticosterone in 0.1-mL vehicles were injected into the albumen of 7-d-old White Leghorn chicken embryos. Embryonic mortality rates and the age after injection at which death occurred were determined. When 0.02 to 20 microg cortisol per egg were injected in saline, total embryonic mortality rate increased in a doseresponse manner, with a median lethal dose (LD50) at 10 microg. Saline injection alone caused a similar mortality rate to that caused by injection of 2 microg cortisol (around 35%). However, whereas mortality among the cortisol-treated embryos was greatest on Days 16 to 18, most of the saline-treated embryos died around the time of injection. The lethal effect of corticosterone, which is endogenous GC in adult chickens, was compared to that of cortisol by injecting both in the same vehicle (a saline:ethanol mixture) and was found to be similar. However, when 2, 10, or 20 microg of corticosterone was injected in oil, mortality rates were lower than those caused by the matching doses of cortisol in saline, probably due to the lower diffusion rate of the steroid out of the oil carrier. Hatch weight was significantly lower in chicks treated with 10 and 20 microg cortisol, and BW of the latter was lower compared with control throughout the 3-mo observation. In conclusion, cortisol and corticosterone are equally active in causing embryonic mortality. Posthatch BW is affected only by GC doses that are equal to or greater than the LD50.

Short-term stress increases testosterone secretion from testes in male domestic fowl.

Prolonged stress inhibits the hypothalamus-pituitary-gonadal (HPG) axis and reduces plasma testosterone (T). However, enhanced secretion of luteinizing hormone (LH) and T has been documented during the initial stages of acute stress in mammals. This study assayed the effect of short-term stress on plasma T and corticosterone (B) in juvenile, pubertal, and adult White Leghorn cockerels. Stress was induced by brief physical restraint of caged juvenile (7 weeks), pubertal (17 weeks), and adult (40 weeks) cockerels, as well as 40-week-old adults reared together in a room lined with wood shavings (group reared). Blood was sampled immediately before restraint (0 time), at the end of a 10-min restraint period, and at 30, 60, and 180 min after 0 time. Restraint resulted in an initial increase in plasma T in all groups, along with a rise in B. Whereas B generally reached its peak level at the end of the restraining period, T peaked 20 min later. The maximum increase of T and B relative to prestress levels (T and B ratios) was similar in all groups, with median T ratio reaching 1.25-1. 5-about half that of the B ratio. Thus, the extent of T and B response to short-term stress was not influenced by basal levels of T, which were highest in adults, and basal levels of B, which were higher in caged adults than in group-reared adults. Injection of ACTH did not induce a greater increase in plasma T than in sham-injected controls. Further, the elevation of T in response to stress was extinguished in castrated adults, indicating that T is secreted from the testes rather than the adrenals in response to stress. When the same regime of blood sampling was applied to adults not subjected to restraint, the T ratio rose by up to 11 times. It can therefore be stipulated that T response depends on the type of stress applied, a factor that should be considered when investigating androgen levels in plasma.

Effect of light source and regimen on growing broilers.

The aim of this study was to determine the effect of different light sources and light schedules on the growth and quality of commercial broilers. In each experiment 810 broiler chicks were divided into 3 groups, 3 replicates per group. All were reared at 20 lux. Body weight and food consumption were recorded weekly. Experiment 1. Birds were reared under 3 light sources: incandescent light bulb, warm-white fluorescent light tube or warm-white mini-fluorescent light bulb. Experiment 2. Birds were reared on 3 light schedules. 23 h light and 1 h dark (23L: 1D) throughout; an increasing light schedule with initial 23L:1D then 8L: 16D increasing daylight gradually to 16L:8D or an intermittently increasing daylight schedule (16:8P) where light and dark periods were shorter but portioned to achieve the same total hours per day up to 16L:8D. Broilers reared under mini-fluorescent light bulb were heavier than those under fluorescent tubes or incandescent bulbs by 49 d. Until 42 d of age, photoperiod had no effect on growth. However, at 49 d broilers reared under 16:8P and 16L:8D regimens were heavier than those or 23L:1D. At 42 d, female broilers on 23L:1D, were heavier than those on 16L:8D and 16:8P. Mortality was higher in groups on 23L:1D than on 16L:8D on 16:8P. At 49 d incidence of leg condemnation was higher in the 16:8P group. However, skin damage was lower in this group than in those on 23L: 1D and 16L:8D.

Should dehydroepiandrosterone replacement therapy be provided with glucocorticoids?

Adrenocorticotrophic hormone (ACTH) induces the concomitant secretion of glucocorticoids (GC) and dehydroepiandrosterone (DHEA) from the adrenal cortex. Whereas GC are catabolic, DHEA is anabolic. Long-term GC administration may result in some deleterious side-effects, such as muscular weakness, atrophy and necrosis, diabetes, fattiness, osteopenia, osteoporosis and avascular necrosis and susceptibility to infections. DHEA ameliorates some deleterious effects of GC, such as diabetes, amino acid deamination, fattiness, hypertension and susceptibility to viraemia. By its anabolic effects in muscles, bones and endothelium, DHEA may diminish the severity of GC-induced myopathy, osteopenia, osteoporosis and avascular necrosis. The natural concomitant secretion of DHEA with GC probably enables the latter to protect the body from ill-effects of stress without exerting their deleterious potency. DHEA secretion diminishes during aging and severe or chronic diseases such as rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Anti-inflammatory and immunosuppressive effects of GC and androgens, including DHEA, are now well established. On the other hand, administration of GC inhibits ACTH secretion, involutes the adrenal cortex and results in further DHEA deficiency, particularly harmful in chronic autoimmune diseases (i.e. RA, SLE). Therefore, the deleterious side-effects of chronic administration of GC emerges from both their direct catabolic activity and the suppression of DHEA production. Whereas, in males, most androgens come from the testes, in females, under GC supplementation, DHEA deficiency leads to nullification of the androgen-dependent anabolism, leaving them exposed to the GC-catabolic effects to a larger extent. The viewpoint presented here claims that under chronic GC supplementation, DHEA replacement therapy may reduce damage caused by GC administration.

The effect of monochromatic light on broiler growth and development.

Artificial illumination, including light quality, is crucial in modem broiler management. In the present study, a new, highly efficient, monochromatic light system has been developed for broilers. One hundred and eighty male broiler chicks (Anak) were divided into four light treatment groups (n = 45) in three replicates each. All birds were housed in a single room previously divided by wooden bars into 12 sealed cells of 1 m2. Feed and water were provided for ad libitum consumption. Light intensity was 0.1 W/m2 at the height of birds' heads and was scheduled for 23 h of light and 1 h of dark during the entire experimental period. Light treatments were: control white (mini-incandescent light bulbs), blue (480 nm), green (560 nm), and red (660 nm). Body weight was recorded periodically, feed consumption was measured daily, and feed efficiency was calculated. Blood samples were taken at 1, 9, and 32 d of age and plasma testosterone was determined. Two necropsies were conducted, at 23 and 35 d of age, and selected glands and organs were weighed. In the group reared under green light, a significant enhancement in weight gain was observed as early as 3 d of age; this gain was maintained during the entire experimental period. Broilers reared under blue light had a later onset of growth enhancement and were significantly heavier than those reared under white and red light at 20 d of age. Plasma testosterone levels were significantly higher in birds reared under blue light. Breast muscle weights were significantly higher in the birds reared under green light at 23 and 35 d of age. These results suggest that green and blue light stimulate growth.

Effects of fenfluramine on body weight, feed intake, and reproductive activities of broiler breeder hens.

Inherited overfeeding and fattiness reduce laying performance in broiler breeder pullets. Although feed restriction is used to compensate for overeating and weight gain, this management practice leads to increases in BW variation, labor cost, and bird stress. Dietary supplementation of anorectic agents, such as fenfluramine, may be an alternative. Anak female prebreeder hens (19 wk of age; n = 10 per group) were treated as follows: daily oral administration of 5, 10, 20, or 40 mg DL-fenfluramine/kg BW or saline with food provided for ad libitum intake or administration of saline and feed restriction. Daily feed intake (FI), laying rate, egg composition, and BW were measured. At 40 wk of age, adipose tissue and ovary weights were measured. Fenfluramine depressed (P < 0.05) BW and FI in a dose-dependent manner, but was less effective in reducing BW than feed restriction. Suppression of FI occurred in two phases: a dynamic phase, coinciding with the rapid growth phase, during which FI declined progressively and a static phase during which FI reached a plateau at a significantly low level until the end of the experimental period. Egg production peaked first in saline-treated hens fed for ad libitum intake, but soon after started to decline. In all fenfluramine-treated and feed-restricted hens, egg production peaked 3 to 4 wk later and remained high until the end of the experiment. There were no differences in egg and egg component weights among the experimental groups. Abdominal adipose tissue weight was reduced by fenfluramine in a dose-related manner, and its weight in the group treated with the highest dose was similar to that of feed-restricted hens. In these two groups, ovarian weight was significantly higher than in the saline-treated hens fed for ad libitum intake, and a small, nonsignificant increase in ovary size was observed in groups treated with the two median doses of fenfluramine. The effect of fenfluramine on egg production was similar to that of feed restriction, but it was not dose-dependent and, thus, not directly related to its leaning effect. In broiler breeder hens, oral fenfluramine may be used for chemical feed restriction and diminution of fattiness without reducing egg production relative to manually feed-restricted hens.

The effect of pyrazine odor on body weight and the weight of various organs in chicks (Gallus gallus domesticus).

Embryonic and posthatch long-term exposure to the odor of 2-methoxy-3-isobutyl-pyrazine (2M3IP) was examined for its potential physiological consequences as reflected in changes in BW and organ weights in domestic chicks (Gallus gallus domesticus). Experiments were run from Day 1 of incubation to the age of 3 wk with a total of 360 fertile chicken eggs. The experimental design consisted of four treatment groups: PP chicks were exposed to 2M3IP during both incubation and posthatch rearing; PC chicks were exposed to 2M3IP during incubation only; CP chicks were exposed to 2M3IP during rearing period only; CC control chicks were not exposed to 2M3IP. Chicks were weighed immediately after hatch and at 3 wk of age, when they were necropsied. Various organs (thyroid, adrenal, testes, comb, liver, spleen, abdominal fat, and the bursa of Fabricius) were removed and weighed. Body weights of both sexes in the PP group were reduced. This reduction was significant in males relative to both CP and CC groups and in females only relative to the CP group. Effects of 2M3IP exposure on the examined organs were as follows: in males, adrenal gland weight significantly increased in the PP group vs all other groups. No weight differences were found between the other inspected organs among the four treatments. In females, comb weight significantly decreased compared with the rest of the groups when 2M3IP exposure occurred during incubation (PC). Further investigation is needed to study the mechanisms that underlie the differential effects of pyrazine odor on male and female chicks.

Testosterone concentrations, testes weight and morphology of mule drakes (Muscovy drake x Khaki Campbell).

1. Mule ducks were produced by naturally mating Muscovy drakes and Khaki Campbell ducks. 2. Semen was collected from 6-month-old mule drakes via an artificial vagina. The fluid was clear without any spermatozoa or spermatids. 3. Testes from 27-week-old mule drakes were smaller in size than those of Khaki Campbell drakes but heavier than Muscovy males of the same age. Histological sections of these testes revealed that spermatogenesis was not complete. 4. Testosterone concentration in the mule drakes was higher than in Muscovy males but similar to Khaki Campbell drakes. 5. Mule drakes have strong sexual drives as a result of high concentrations of testosterone, but, because spermatogenesis is incomplete, their semen had no sperm.

The effect of enhanced milk yield of dairy cows by frequent milking or suckling on intake and digestibility of the diet.

Groups of 9 or 10 cows were assigned to one of three treatments 1) machine-milking three times daily, 2) machine-milking six times daily, and 3) suckling three times daily in addition to machine-milking three times daily. Treatments were conducted during the first 6 wk postpartum. During wk 5, digestibility of the diet was estimated by the indigestible neutral detergent fiber method. During wk 6, milk yield and dry matter intake (DMI) were recorded daily, and plasma concentrations of glucose, nonesterified fatty acids, urea, protein, growth hormone, insulin, insulin-like growth factor I, oxytocin, and prolactin were determined. Milk yields were 38.5, 46.8, and 52.7 kg/d, and DMI were 18.1, 21.2, and 17.2, for cows on treatments 1, 2, and 3, respectively. Plasma glucose concentrations decreased, and plasma nonesterified fatty acid concentrations increased, for cows on treatments 2 and 3 compared with cows on treatment 1. Digestibility of dry matter was 57.5, 60.5, and 60.6%; of organic matter was 62.6, 64.6, and 66.8%; and of crude protein was 59.3, 62.7, and 64.6% for cows on treatments 1, 2, and 3, respectively. Concentrations of all assayed hormones, except insulin, increased moderately for cows on treatment 2 compared with cows on treatment 1 and increased dramatically for cows on treatment 3. Insulin concentrations followed the opposite trend. The DMI were positively related to milk yields and negatively related to oxytocin concentrations. Digestibility was negatively related to plasma glucose concentrations in a nonlinear pattern. The possible involvement of hormones in improvement of digestibility is discussed.

Large-scale preparation of biologically active recombinant chicken obese protein (leptin).

Prokaryotic expression vector pMON3401 encoding full size A(-1) chicken leptin (AF012727) was prepared by PCR of previously described cDNA. Escherichia coli cells transformed with this vector overexpressed large amounts of chicken leptin upon induction with nalidixic acid. The expressed protein found in the inclusion bodies was refolded and purified to homogeneity on a Q-Sepharose column, yielding two electrophoretically pure fractions (leptin-1 and leptin-2), eluted from the column by 100 and 125 mM NaCl. Both fractions showed a single band of the expected molecular mass of 16 kDa and were composed of over 95% of monomeric protein. The biological activity of both fractions, resulting from proper renaturation, was further evidenced by their ability to stimulate proliferation of leptin-sensitive BAF/3 cells transfected with a long form of human leptin-receptor construct and by lowering the food intake of starved chicken following intravenous or intraperitoneal injections.

Increased weight gain and effects on production parameters of Holstein heifer calves that were allowed to suckle from birth to six weeks of age.

Forty Holstein heifer calves were assigned to two treatments. Control calves (n = 20) were fed milk replacer in open buckets, and calves that were allowed to suckle (n = 20) were paired and suckled the same dam three times daily. Treatments were conducted during the first 6 wk following birth; thereafter, all calves received the same management, and weaning was at 60 d of age. During treatment, calves that were allowed to suckle had significantly higher average daily gains than did control calves. However, at 12 wk of age, calves that were allowed to suckle had significantly lower body weights (BW) than did control calves. Age at conception was significantly lower, and BW at conception and conception rate tended to be higher, for calves that were allowed to suckle. Calving age was significantly earlier for heifers that had been allowed to suckle as calves, and BW at calving also tended to be higher. Height at the withers after calving was also significantly higher for those heifers. Milk production during first lactation tended to be higher for the heifers that had been allowed to suckle as calves. Our results indicated that heifer calves that suckled milk during the first 42 d of age had higher average daily gains, higher height at the withers, an earlier age at calving, and a tendency for greater milk production than did calves fed milk replacer.

Nimodipine's protection against corticosterone-induced morphological changes in the hippocampus of young rats.

Sustained high levels of corticosterone (CORT), one of the major stress-induced hormones in the rat, were suggested as generating 'accelerated brain aging' and were shown to induce both specific brain changes in the hippocampus and learning impairments in young and middle-aged Fischer-344 rats. Evidence that altered calcium (Ca) homeostasis may play a major role in brain aging has accumulated over the last decade. Recently, new data established a connection between glucocorticoids and voltage-activated Ca influx in aged hippocampal neurons. In the present study, an attempt was made to block the CORT-induced 'accelerated aging' by the simultaneous administration of the L-type Ca channel blocker nimodipine. CORT or placebo sustained-release (SR) pellets were implanted subcutaneously in 3 months old Fischer male rats. Each group was further sub-divided between nimodipine and placebo SR treatments. Characteristic CORT-induced morphological changes were observed in pyramidal hippocampal cells, such as at the CA1 and CA4 sub-regions (22.2% +/- 7.7 and 28.6% +/- 8.4 of pyknotic cells without clear nuclei, respectively). Concomitant treatment with nimodipine conferred full protection against CORT-induced morphological changes (e.g. 3.2% +/- 0.8 and 2.1% +/- 1.9 of pyknotic cells in CA1 and CA4, n = 7 rats in each group; P < 0.04). The neuroprotective efficacy of nimodipine supports the theory of Ca involvement in CORT related 'accelerated brain aging'.

Hypothalamic obese, functionally castrated hens are hypersensitive to estrogenic modulation of lipid metabolism.

Estradiol benzoate (E2) increases plasma lipids in hypothalamic obese, functionally castrated (OFC), obese laying (OL), and control laying hens (CONT). However, E2 reduces fattiness in OFC but not in OL or CONT hens. Antiestrogen, such as tamoxifen (TAM), reduces plasma lipids in OL and CONT, but not in OFC, hens and has no effect on fattiness in any of them. Apolipoprotein VLDL-II (apo-VLDL-II), lipoprotein lipase (LPL), and rate of lipolysis may mediate these estrogenic effects. In the present study, effects of E2 and TAM on fattiness, plasma apo-VLDL-II, in vitro lipolysis, and LPL activity in postheparin plasma and abdominal adipose tissue (AAT) were determined in OFC, OL, and CONT hens. Basomedial hypothalamic lesions were performed in 3-month-old White Leghorn hens. At the static phase, 10 months later, OFC OL, and CONT hens were divided into three subgroups and injected IM on alternate days, with either 2 mg E2/kg b.wt., 10 mg TAM/kg, or vehicle corn oil, for 5 weeks. In OL and OFC hens, body and AAT weights were higher than in CONT poullets. Food intake and ovarian weight were similar in OL and CONT, higher than in OFC hens. Plasma LPL activity was higher, whereas plasma apo-VLDL-II and stimulated lipolysis were lower in OFC than in OL and CONT hens. In OFC hens LPL activity per unit of AAT was half than in OL and CONT. Total LPL activity in AAT was similar in OFC and CONT and higher in OL hens. Levels of basal lipolysis were similar in all experimental hens. TAM did not affect any of the measured parameters in OFC hens. In OL and CONT hens, TAM depressed apo-VLDL-II, increased plasma LPL activity, but had no effects on AAT LPL activity, on stimulated lipolysis, or fattiness. E2 increased apo-VLDL-II to similar levels in all groups and reduced LPL activity in plasma and AAT of obese hens. Only in OFC hens did E2 enhance basal and stimulate lipolysis and reduce FI and fattiness. We conclude that in adult laying hens, unlike in cockerels and juvenile hens, estrogen reduces lipid incorporation in fat depots by enhancing apo-VLDL-II production that reduces plasma and AAT LPL activity. This may increase lipoprotein available for incorporation into developing yolks. The lack of estrogen in OFC hens reduces circulating apo-VLDL-II and thus increases LPL activity and amount of fat depots.

Intermingling heavy and light strain chickens may cause social stress.

The present study examines the effects of intermingling day-old broiler chicks with 2-wk-old light strain chicks, on body weight, general activity, feeding behavior, feather condition, and heart size of the broilers. Fifteen groups of chicks (five for each treatment) were raised until 6 wk of age in 1 x 2 m experimental pens. Each group consisted of 10 broiler chicks in Treatment 1 (control pens), 8 broiler, and 2 light strain chicks in Treatment 2 (8:2), and 5 broiler with 5 light strain chicks in Treatment 3 (5:5). The feeding program consisted of a commercial starter ration (21% protein, 3,000 kcal ME/kg) for the first 4 wk followed by a finishing ration (18% protein, 3,150 kcal ME/kg). Feed and water were provided for ad libitum consumption. Body weight did not differ between Treatment 1 (controls) and the "intermingled" broilers. Feather condition was significantly poorer among the 5: 5 groups than in the controls. Heart weight (a possible indicator of chronic stress) in broilers of the 5:5 groups was significantly heavier than in the controls. No differences in the general activity parameters were found between broilers of the various treatments. Pecking at feed among broilers was significantly greater (P < 0.05) in the 8:2 groups than in both control and 5:5 groups. During the first 6 wk after hatching, intermingling broiler chicks with equal numbers of light strain chicks that are 2 wk older may lead to long-term chronic stress for the broilers.

Relationship between frequent milking or suckling in early lactation and milk production of high producing dairy cows.

Groups of 9 or 10 cows were assigned to one of three treatments 1) machine-milking three times daily, 2) machine-milking six times daily, and 3) suckling three times daily in addition to machine- milking three times daily. Treatments were conducted during the first 6 wk postpartum; thereafter, all cows were milked three times daily. During treatment, milk production was highest for suckled cows and lowest for cows milked three times daily. The DMI were similar for suckled cows and cows milked three times daily but higher for those milked six times daily. Body weight loss was greatest for suckled cows and least for cows milked three times daily. During wk 7 to 18 postpartum, cows milked six times daily exhibited a carry-over effect on milk production that was greater than that of other groups, During treatment, plasma growth hormone and IGF-I concentrations were elevated for suckled cows and, to a lesser extent, for cows milked six times daily. Prolactin and oxytocin similarly increased, but insulin decreased in suckled cows and, to a lesser extent, in cows milked six times daily. Posttreatment differences persisted for insulin and IGF-I, but not for the other hormones. Increased frequency of udder emptying increased milk production, and suckling was superior to machine-milking. High milk production was associated with elevated growth hormone, IGF-I, prolactin, and oxytocin, although cause and effect could not be established. The failure of suckled cows to increase feed intake to match output requires further investigation.