Free Corticosteroid Concentrations Research Articles

Fetal Concentrations of Budesonide and Fluticasone Propionate: a Study in Mice.

The study goal was to evaluate the transplacental transfer of two corticosteroids, budesonide (BUD) and fluticasone propionate (FP), in pregnant mice and investigate whether P-glycoprotein (P-gp) might be involved in reducing BUD transplacental transfer. Pregnant mice (N = 18) received intravenously either low (104.9μg/kg) or high (1049μg/kg) dose of [3H]-BUD or a high dose of [3H]-FP (1590μg/kg). In a separate experiment, pregnant mice (N = 12) received subcutaneously either the P-gp inhibitor zosuquidar (20mg/kg) or vehicle, followed by an intravenous infusion of [3H]-BUD (104.9μg/kg). Total and free (protein unbound) corticosteroid concentrations were determined in plasma, brain, fetus, placenta, kidney, and liver. The ratios of free BUD concentrations in fetus versus plasma K(fetus, plasma, u, u) 0.42 ± 0.17 (mean ± SD) for low-dose and 0.38 ± 0.18 for high-dose BUD were significantly different from K = 1 (P < 0.05), contrary to 0.87 ± 0.25 for FP, which was moreover significantly higher than that for matching high-dose BUD (P < 0.01). The BUD brain/plasma ratio was also significantly smaller than K = 1, while these ratios for other tissues were close to 1. In the presence of the P-gp inhibitor, K(fetus, plasma, u, u) for BUD (0.59 ± 0.16) was significantly increased over vehicle treatment (0.31 ± 0.10; P < 0.01). This is the first in vivo study demonstrating that transplacental transfer of BUD is significantly lower than FP's transfer and that placental P-gp may be involved in reducing the fetal exposure to BUD. The study provides a mechanistic rationale for BUD's use in pregnancy.

Some problems with the concept of a cut-off point for determining when an animal's welfare is at risk

At what level of change in physiology or behaviour is an animal's welfare at risk? At first glance this question, addressed by Barnett and Hemsworth (1990), would seem to be of central importance to scientific studies of animal welfare. However, the question itself raises important issues which should be discussed. The notion of a point or 'cut-off line' at which welfare becomes 'at risk' necessarily implies that there is also an area in which welfare is 'not at risk'. The term 'at risk' is not specifically defined by Barnett and Hemsworth, but Barnett and Hutson ( 1987, p. 1 ) equate welfare which is at risk with unacceptable welfare. Therefore, on one side of this cut-off line welfare is acceptable, while on the other side it is unacceptable. Does the apparent scientific rigour of a cut-off line outweigh the dangers of mistakenly assessing the welfare of certain animals as being acceptable and not at risk? Consider three pigs kept in three different housing conditions, A, B and C. Measurement of their plasma free corticosteroid concentrations shows that the animals in Conditions A and B experience sustained rises of 45 and 30%, respectively, relative to the animal in Condition C (Fig. 1 ). Following Barnett and colleagues' ( 1987, 1990 ) suggestion that increases in free corticosteroid of > 40% represent a risk to a pig's welfare, we would conclude that only the welfare of the animal in Condit ion A is at risk. However, to many, the data would suggest that there is also a clear difference in the physiological responses of the other two animals that may be indicative of welfare problems in Condit ion B relative to Condit ion C. Should we, therefore, consider that both these pigs fall into the same 'not at risk' category, as Barnett and Hutson

The effects of aversively handling pigs, either individually or in groups, on their behaviour, growth and corticosteroids

The influence of three handling treatments, imposed for 10 weeks from 15 kg liveweight, on the behaviour, growth, subsequent reproductive performance and free corticosteroid concentrations were studied in 60 female pigs. The pleasant treatment involved individually handling the pig in a pleasant manner (e.g. gentle stroking). There were two unpleasant handling treatments; one involved individually handling the pig in an unpleasant manner (e.g. brief shocking or brief slapping) whenever the pig failed to withdraw from the experimenter and the other involved handling the pig within a group in an unpleasant manner whenever the pig failed to withdraw from the experimenter. The individual handling treatments were imposed for 30 s day −1 for 5 days week −1 and the group handling treatment was imposed for 2.5 min day −1 for 5 days week −1. There were no differences between treatments in growth rates over the 10-week period; however, the pigs in the pleasant handling treatment had a higher ( P<0.01) growth rate in the first 5 weeks of the handling period than pigs in the two unpleasant handling treatments. The feed conversion efficiency of pigs in the pleasant handling treatment was also superior ( P<0.05) in the first 5 weeks. The pigs in the unpleasant handling treatments were more ( P<0.01) fearful of humans, as indicated by their approach behaviour to a stationary experimenter at 20 weeks of age, and those that were individually handled experienced a greater ( P<0.05) increase in their free corticosteroid response to humans at 24 weeks of age than did pigs in the pleasant handling treatment. There was no physiological evidence at 24 weeks of age that the pigs in the unpleasant handling treatments were chronically stressed. These results indicate that aversive handling of pigs, either as individuals or as members of a group, will adversely affect the growth performance of the young pig. The fact that there was no evidence that the unpleasantly handled pigs were chronically stressed and that some recent results in this area are contradictory are considered in the discussion.

The effect of design of tether and stall housing on some behavioural and physiological responses related to the welfare of pregnant pigs

Plasma-free corticosteroid concentrations, aggressive behaviour and levels of motivation to socially interact in a standard test were determined in two experiments. The two experiments used 32 and 40 pigs, respectively, and differences between experiments were to take into account the effects of neighbouring pigs between treatments (Experiment 1) and positional effects in the shed (Experiment 2). There were five treatments involving two types of housing (cage-stalls and tetherstalls), two designs of stall division (bars and mesh, that affected the level of aggressive behaviour between neighbouring pigs) and a control treatment of group-housed pigs. Pigs in tether-stalls separated by bars showed evidence of a chronic stress response; free corticosteroid concentrations were 1.28 and 1.21 ng ml −1 in Experiments 1 and 2 compared with 0.63 and 0.54 ng ml −1 for group-housed pigs, respectively ( P < 0.01), and these changes were sufficient to affect plasma glucose concentrations ( P < 0.01). Separating the tether-stalls with mesh obviated the increase in free corticosteroid concentrations (0.68 and 0.53 ng ml −1 in Experiments 1 and 2, respectively). Pigs housed in cage-stalls separated by bars or mesh showed only slight increases in free corticosteroid concentrations compared with group-housed pigs in Experiment 1 (0.87, 0.81 v. 0.63 ng ml −1, respectively, P < 0.05) and no differences in Experiment 2 ( P > 0.05). The increase in free corticosteroid concentrations in Experiment 1 was of insufficient magnitude to affect plasma glucose concentrations. Behaviourally, pigs in the cage-stalls with bars and tether-stalls with bars showed higher levels ( P < 0.05) of aggression than pigs in their modified counterpart treatments using mesh divisions, and the proportions of retaliatory and withdrawal behaviours were similar in the two treatments. Pigs in cage-stalls with bars moved backwards and forwards more often ( P < 0.05) than pigs in the tether-stalls with bars and this increased movement, possibly in response to aggression, may be a factor affecting the different physiological responses in cage-stall and tether-stall treatments; in cage-stalls aggressive behaviour sequences may be terminated in a manner that does not induce a physiological response. In conclusion, the two experiments confirm that pigs housed in tether-stalls can show evidence of reduced welfare as a consequence of the design of the tether-stall divisions, but show that the design of the cage-stall has no effect on physiological responses. Thus, in this context, cage-stall housing does not appear to pose a risk to welfare.

The effects of genotype on physiological and behavioural responses related to the welfare of pregnant pigs

Plasma free-corticosteroid concentrations, aggressive behaviour and levels of motivation to socially interact and explore a novel arena were observed in an experiment to examine whether differences previously observed between pigs in neck-tethers and groups are shown by pigs of different genotypes. Thirty-two pregnant gilts of 2 genotypes were housed in either tether stalls or groups. The 2 genotypes were mainly Large White×Landrace stock, but one had been intensively selected on the basis of growth performance. Genotypic differences had previously been observed in protein and energy metabolism, and the present experiment also showed differences in their behaviour (increased activity and a decreased motivation to socially interact in the intensively selected genotype) and free-corticosteroid concentrations (40% lower in the intensively selected genotype). In spite of these differences, the behavioural and physiological responses to housing treatments were similar. In tether stalls, pigs of both genotypes had a higher frequency of retaliation and a lower frequency of withdrawal in response to aggressive interactions than group-housed pigs. There were 50 and 56% increases in free-corticosteroid concentrations in response to tether housing in the 2 genotypes, providing evidence of a chronic stress response of a magnitude sufficient to suggest a risk to welfare in the design of tether stall used in this experiment.

The effects of design of individual stalls on the social behaviour and physiological responses related to the welfare of pregnant pigs

Plasma free-corticosteroid concentrations, aggressive behaviour and levels of motivation to socially interact and explore a novel environment were observed in an experiment to test the hypothesis that the chronic stress response previously observed in tether housed pigs may have been due to unresolved aggression between adjacent pigs, and was attributable to the design of the stall. Twenty-five pregnant gilts were housed in 4 treatments: unmodified tether stalls; modified tether stalls (designed to reduce aggressive interactions between adjacent pigs by the addition of steel mesh to part of the stall division); cage stalls (also with mesh divisions); and a group. Gilts in the unmodified tether stalls showed a sustained elevation of free-corticosteroid concentrations, indicative of a chronic stress response, changes in their level of motivation to interact with stimulus pigs in a standard test, and a higher proportion of aggressive interactions between neighbouring pigs resulting in withdrawal rather than retaliation. These data suggest reduced welfare in the unmodified tether stalls. The addition of mesh to the sides of the tether stalls reduced the number of interactions between neighbouring pigs compared to the unmodified tether stalls treatment and virtually eliminated aggressive interactions. Concomitant to the reduction in aggressive interactions was a reduction in free-corticosteroid concentrations, suggesting that the welfare of pigs in the modified tether stalls, cage stalls and group treatments was similar. It was concluded that modifying the design of the tether stall to minimize aggressive interactions between adjacent pigs improves welfare by avoiding a chronic increase in free-corticosteroid concentrations.

The influence of inconsistent handling by humans on the behaviour, growth and corticosteroids of young pigs

The influence of 4 handling treatments on the behaviour, growth and free corticosteroid concentrations were studied in 32 young female pigs housed in individual pens. The pleasant treatment involved stroking the pig whenever it approached the experimenter, the unpleasant treatment involved forcing the pig away whenever it approached the experimenter and the inconsistent treatment was a combination of unpleasant and pleasant treatments (imposed at a ratio of 1:5). These 3 treatments were imposed for 3 min each, 3 times per week, from 7 to 13 weeks of age. The fourth treatment, minimal handling, involved minimal contact with humans during this 6-week period. Gilts in the pleasant and minimal handling treatments had higher ( P < 0.05) growth rates and feed conversion efficiencies over the first 2 weeks of the study than gilts in the unpleasant and inconsistent handling treatments. The gilts in the unpleasant and inconsistent handling treatments had higher ( P < 0.01) free corticosteroid concentrations in the absence of humans at 14 weeks of age and were more ( P < 0.05) fearful of humans, as indicated by less approach to a stationary human, at 14 weeks of age than gilts in the pleasant and minimal handling treatments. It was concluded that the unpleasant and inconsistent handling treatments resulted in a chronic stress response with consequent adverse effects on growth performance. The implications of these results for the reproductive performance and welfare status of breeding pigs are discussed.

The effects of pregnancy and parity number on behavioural and physiological responses related to the welfare status of individual and group-housed pigs

Plasma free-corticosteroid concentrations, aggressive behaviour and motivation to socially interact and explore a novel environment were observed in 39 female pigs housed in either groups of 4–7 animals or tether stalls over 2 parities. Gilts in tethers in their first pregnancy had significantly higher free-corticosteroid concentrations compared to non-pregnant gilts housed in tethers and gilts housed in a group of 7 (4.1, 2.9 and 3.0, ng ml −1, respectively). A significant difference was also found between free-corticosteroid concentrations of group- and tether-housed animals at the second pregnancy (2.6 and 4.7, ng ml −1, respectively), but there were no effects of previous experience of tethers or parity number. The chronically elevated free-corticosteroid concentrations were associated with reduced immunological reactivity (72 and 48% reductions in IgM and IgG response at 8 days after challenge, respectively) in tether- compared to group-housed pigs. In standardized motivation tests, social interaction, but not exploration, was higher in tether-compared to group-housed sows in both first and second pregnancies. In tethers, a higher proportion of social interactions between adjacent animals were aggressive and a higher proportion of these involved retaliation (25 vs. 0%) compared to the social behaviour of group-housed animals. It was concluded that unresolved aggression in tether-housed pigs may result in a chromic stress response with adverse effects on their welfare status. The effect of the design of stall divisions on the nature and level of aggressive behaviour warrants investigation.

Effects of social environment on welfare status and sexual behaviour of female pigs. I. Effects of group size

This study examined the effects of housing 24 adult female pigs in groups of 2, 4 or 8 with a space allowance of 1.4 m 2 per pig on welfare status, as indicated by plasma free-corticosteroid concentrations and behaviour patterns, and sexual behaviour. Housing gilts in pairs resulted in an increase in free corticosteroid concentrations(measured 11 and 84 days after the start of the treatments) and an increase in the number of observations of lying behaviour without physical contact with another pig (recorded 21 days after entering the treatment) compared to housing in groups of 4 or 8. Overall mean free corticosteroid concentrations (±S.E.) were 3.1 ± 0.29, 2.3 ± 0.26 and 1.9 ± 0.12 ng ml −1, and the mean numbers of observations of lying-alone behaviour (out of a total of 88 observations) were 6.4, 3.6 and 1.9 for gilts housed in groups of 2, 4 or 8, respectively. Although there were no differences between treatments in agonistic behaviour around the time of feeding, these data suggest there are undefined social stressors in pigs housed in pairs. Housing treatment had no significant effects on sexual behaviour. However, the mating rate was low in all treatments, possibly due to a sub-optimal space allowance.

Effects of social environment on welfare status and sexual behaviour of female pigs. II. Effects of space allowance

This study examined the effects of housing groups of adult female pigs (6 pigs per group) with a space allowance of 1, 2 or 3 m 2 per pig on sexual behaviour and welface status, determined by plasma free-corticosteroid concentrations. A lower percentage of gilts was detected in oestrus and a lower percentage of gilts was mated when housed with a space allowance of 1 m 2 per gilt than with a space allowance of either 2 or 3 m 2 per gilt (oestrus detection rate of 79, 88 and 100%, respectively, and a mating rate of 77, 85 and 97%, respectively). There was a significant increase in plasma free-corticosteroid concentrations when gilts were housed with a space allowance of 1 m 2 per gilt. The elevated free corticosteroid levels of gilts in the 1 m 2 per gilt treatment suggests that a chronic stress response due to crowding may have been responsible for the apparent impairment in the sexual behaviour of these animals.

The influence of handling by humans on the behaviour, reproduction and corticosteroids of male and female pigs

The influence of three handling treatments on the behaviour, reproduction and free corticosteroid concentrations was studied in 15 male and 30 female pigs. Two handling treatments, considered as pleasant and unpleasant, were imposed for 5 min, three times per week from 11 weeks of age. The third handling treatment involved minimal contact with humans from 11 weeks of age. In a 3-min test at 18 weeks, pigs in the pleasant treatment were quicker ( P<0.01) to enter an area within 0.5 m of the experimenter and had more interactions ( P<0.05) with the experimenter than pigs in the unpleasant and minimal treatments. Gilts in the unpleasant treatment had a lower ( P<0.05) pregnancy rate at the second oestrus when mated to non-experimental boars than gilts in the pleasant treatment (33.3 and 87.5%, respectively). Boars in the unpleasant treatment had smaller ( P<0.05) testicles at 23 weeks of age and attained a coordinated mating response at a later age ( P<0.05) than boars in the pleasant treatment (53.2 and 63.3 cm 2, and 192 and 161 days, respectively). In addition, pigs in the unpleasant treatment had higher ( P<0.05) free corticosteroid concentrations in the absence of humans at 20 weeks (gilts) and 27 weeks (boars) than pigs in the pleasant treatment (boars and gilts combined, 2.4 and 1.7 ng ml −1, respectively). For many of the reproductive parameters, the effect of the minimal handling treatment was intermediate to that of the other two treatments. It was concluded that the unpleasant handling treatment resulted in a chronic stress response, with consequent adverse effects on reproduction.

Effects of chronic stress on some blood parameters in the pig

Plasma samples from juvenile female pigs exhibiting a chronic stress response, evidenced by higher free corticosteroid concentrations, changes in behaviour and reduced growth rates, were analysed for plasma concentrations of total protein, albumin, glucose, urea and cholesterol. Chronic stress was associated with elevated levels of plasma total protein and glucose and lower levels of plasma urea.

The influence of handling by humans on the behavior, growth, and corticosteroids in the juvenile female pig

The influence of two handling treatments by humans on the behavioral response to the presence of humans, growth performance, and total and free corticosteroid concentrations in the presence and absence of humans was studied in the female pig. The handling treatments, considered as pleasant and unpleasant, were imposed three times per week for 2 min in duration from 11 to 22 weeks of age. Gilts in the unpleasant handling treatment spent less ( P < 0.01) time within 0.5 m of the experimenter and displayed fewer ( P < 0.01) interactions with the experimenter in a 3-min test conducted at 25 weeks of age. In addition, gilts in this treatment had a slower ( P < 0.05) growth rate from 11 to 22 weeks of age and had higher ( P < 0.001 and P < 0.01) corticosteroid concentrations at rest and in response to the presence of the experimenter, respectively, at 24 weeks of age. It was concluded that the unpleasant handling treatment resulted in both chronic and acute stress responses.

Relationship between plasma corticosteroids and weight change in recently parous lactating and dry sheep

Twin-bearing ewes were assigned to three treatments at lambing. Treatment 1 was the adult with both lambs retained; treatment 2 was the adult with one lamb retained; and treatment 3 was the adult alone. All sheep were fed on an amount calculated to maintain an adult and one lamb, and consequently animals in treatments 1, 2 and 3 lost, maintained and gained weight respectively. Chronic under-nutrition of the lactating ewe (treatment 1) resulted in a small increase in the maximum corticosteroid binding capacity and a large increase in total corticosteroid levels in peripheral plasma, resulting in a significant increase in biologically active (free) corticosteroid concentrations. In dry sheep (treatment 3) no such increase in free hormone concentration occurred. There was a significant negative relationship between free corticosteroid concentrations and weight change during both the 2-week intervals and the entire 6-week experimental period.