Urinary excretion of free glucocorticosteroids and testosterone in the Mongolian gerbil (Meriones unguiculatus): effects of long-acting corticotrophin and human gonadotrophin

Acute poisoning of silver gulls (Larus novaehollandiae) following urea fertilizer spillage

Two episodes of accidental urea toxicosis are described in wild silver gulls (Larus novaehollandiae) following spillage of fertilizer grade urea at a commercial shipping facility near Perth, Western Australia. In both cases, urea spillage had been seen to contaminate freshwater wash-down pools on the wharves where ships were being unloaded and gulls were seen to be drinking and washing in the pools nearby the spillages. Affected birds were found moribund or dead. Necropsy and histopathological findings were non-specific and consisted of mild to moderate congestion of visceral organs and brain. Analysis of a water sample collected during Case 1 revealed a very high urea concentration of 4.124 mol/l (pH 5.5), and fluid from the proventriculus of two birds had urea concentrations of 382 and 308 mmol/l, respectively. Nine birds were examined during the second episode (Case 2) and, from heparinized heart blood samples collected (n = 5), the mean plasma urea (288 +/- 92.0 mmol/l), ammonia (43.9 +/- 34.2 mmol/l) and uric acid (7.45 +/- 1.99 mmol/l) concentrations were markedly elevated above the reference ranges for all bird species. Proventricular contents (n = 7) similarly contained high concentrations of urea (394 +/- 203 mmol/l) and ammonia (9.3 +/- 15 mmol/l). The probable mechanisms of urea and ammonia toxicity in these birds are discussed.

Social stress in laboratory rats: hormonal responses and immune cell distribution

Previous experiments with chronically coexisting groups of Long-Evans rats indicated differences in many aspects of blood cellular immunity between winner and loser rats. The present study investigated the specific hormonal response patterns of winners and losers in relation to changes in numbers of blood immune cells. At the beginning of a 7 day period of chronic confrontation, a partition wall was removed between two neighboring rat groups, each containing a male-female pair. Fights for dominance between the males resulted in fast establishment of stable dominance relationships. At day 7 of the confrontation, winner males showed stable concentrations of CBG (corticosteroid-binding globulin) and even reduced titers of total CORT (corticosterone). In contrast, a marked decrease in CBG and unaffected total CORT concentrations were determined in loser males. Increased norepinephrine (NE) and epinephrine (E) titers were evident only in losers. In addition, reduced testosterone titers were observed in the bitten loser male subgroup. All male subgroups lost body mass with most pronounced reductions in loser males. Confrontation caused a marked granulocytosis, especially in loser males. NE concentrations in loser males correlated with the percentage of granulocytes. Numbers of CD4 T-cells were lowered in all loser males and in non-biting winners. In not-bitten losers also a reduced number of CD8 T-cells was determined. Interestingly, higher pre-confrontational NE titers were detected in future bitten loser and future biting winner males relatively to not-bitten losers and non-biting winners. The present report indicates that differential hormonal response patterns may play an important role in some of the immunological differences observed between winner and loser males under stressful social conditions.

The influence of fasting on blood and plasma composition of herring gulls (Larus argentatus)

Populations of scavenging seabird species in the North Sea may fluctuate with an artificial food source: the availability of fishery waste. To document this impact, it is necessary to assess the birds' nutritional status during periods with decreased fishing activity. Reference data for this purpose was collected from 22 herring gulls investigated during laboratory fasting. After 6 d of food deprivation and body mass losses exceeding 15%, the first birds entered starvation phase 3. Comparatively, this is a rather weak fasting capacity. Plasma levels of total protein and thyroid hormones decreased and beta-hydroxybutyrate increased with fasting duration. The leucocyte proportions were shifted from lymphocytes to heterophils. After 3 d of refeeding, most of the fasting changes were reversed. Plasma enzyme activities increased and hematocrit, hemoglobin, and erythrocyte numbers decreased in both fasting and control birds, most likely as a result of experimental stress and repeated blood sampling. Glucose, cholesterol, monocytes, basophils, and glycosylated hemoglobin remained fairly constant. Triglycerides, free fatty acids, uric acid, and urea varied significantly, but changes were not as clearly a result of fasting. Therefore, total protein, beta-hydroxybutyrate, triiodothyronine, thyroxine, and lymphocyte and heterophil percentages may be the most reliable indicators of the nutritional status and the condition of free-living herring gulls.

Saliva cortisol and testosterone in the guinea pig: measures for the endocrine function of adrenals and testes?

For collection of saliva, cotton buds (Q-tips) were inserted into the guinea pig's cheek pouch, parallel with the cheek teeth. Within 5 min, sufficient fluid was collected for cortisol and testosterone measurements. In saline-treated animals, saliva cortisol and testosterone were about 15 ng/mL and 1.5 ng/mL, corresponding to plasma levels of 52 ng/mL and 5.9 ng/mL. Within 2-4 h after administration of 20 IU ACTH, saliva and plasma cortisol concentrations were strikingly elevated: saliva: 125 ng/mL (2 h), 157 ng/mL (4 h); plasma: 458 ng/mL (2 h), 736 ng/mL (4 h). This treatment did not influence testosterone in saliva, but reduced it in plasma (2.4 ng/mL (4 h)). In animals receiving 100 IU HCG, saliva testosterone remained unchanged, whereas its plasma levels were markedly raised (9.6 ng/mL (2 h), 12.5 ng/mL (4 h)). These results show that saliva cortisol offers promise as a noninvasive method of monitoring changes in guinea pig adrenocortical function. Saliva testosterone, on the other hand, does not correlate with plasma values; hence it cannot be used to assess testicular function in the guinea pig.

Excretion of electrolytes, free cortisol and aldosterone-18-oxo-glucuronide in 24-hr urines of the Mongolian gerbil (Meriones unguiculatus): effect of lysine-vasopressin and adrenocorticotrophin administration, and of changes in sodium balance

1. Administration of lysine-vasopressin (LVP, 1 IU/animal) strongly reduced electrolyte excretion in 24 hr urines of adult male Mongolian gerbils, but had no effect on free cortisol (C) or aldosterone-18-oxo-glucuronide (Aldo-gluc.) excretion. 2. (1-24) ACTH, given at a dosage of 20 IU/animal, increased C and Aldo-gluc. excretion but did not influence electrolyte excretion. 3. Fluid intake and potassium excretion were decreased in animals offered a control or a sodium-deficient diet; contrasting, excretion of C was stimulated. 4. In contrast to other rodents, Aldo-gluc. excretion showed no changes in Mongolian gerbils offered a sodium-deficient diet, but was diminished in animals either fed a control diet or given saline (154 mmol/l) as drinking water.

Urinary excretion of free progestins, androgens, and estradiol after injection of (1-24)ACTH in the Mongolian gerbil

Injection of a "long-acting" synthetic adrenocorticotrophin [(1-24)ACTH, 20 IU/animal] into Mongolian gerbils resulted in a 3.1 fold increase of urinary free testosterone excretion over 2 days. It was accompanied by an elevation of urinary free progesterone (2.1 fold), 17-hydroxyprogesterone (2.5 fold), DHEA (2.8 fold) and androstenedione (3.0 fold) excretion. Similarly, administration of human chorionic gonadotrophin (HCG, 100 IU/animal) increased urinary excretion of free testosterone (2.3 fold), progesterone (4.1 fold), 17-hydroxyprogesterone (2.9 fold), DHEA (4.6 fold), androstenedione (5.4 fold) and of estradiol (2.9 fold). Data presented in this work show that the measurement of urinary free steroid excretion represents a reliable index for the secretory activity of the adrenal-gonadal-axis, and that it may in some aspects be more practicable than the measurement of steroid plasma levels, especially in small laboratory animals, enabling us to monitor the excretion of various steroids over longer time periods without stressing the animals by handling/or blood sampling.