Relative Weight Of Adrenal Glands Research Articles

Glucocorticoid hypersecretion following intracerebroventricular injection of ethylcholine mustard aziridinium ion in rats

To investigate whether cholinergic hypofunctions in the brain influence hypothalamic-pituitary-adrenal activity, we examined the effects of cholinergic neurotoxin ethylcholine mustard aziridinium ion on basal and stress-induced levels of corticosterone in rats. Blood sampling from rats following intracerebroventricular injection of saline (5 μl, as a control) or this neurotoxin (5 nmol/5 μl) was performed over a day in one series, and was taken before, during and after an immobilization stress exposure in another series. Plasma levels of corticosterone and adrenocorticotropin were determined by the radioimmunoassay. The basal levels of plasma corticosterone and adrenocorticotropin over a day were significantly higher in the neurotoxin-treated rats, compared with the control rats (corticosterone, P<0.001; adrenocorticotropin, P<0.05). Further, relative adrenal gland weight of the neurotoxin-treated rats was significantly greater than that of the control rats ( P<0.05). However, responses in plasma corticosterone level caused by the immobilization stress in the neurotoxin-treated rats were not different from those in the control rats. The present study demonstrated that damage to the cholinergic neurons in the brain increased hypothalamic-pituitary-adrenal activity over a day, probably due to freedom from inhibitory influences of the hippocampal cholinergic system, but that this damage did not influence stress-induced changes in plasma glucocorticoid level.

Longevity and aging of mice from lines divergently selected for body weight for over 90 generations.

We have analysed the differences between longevity and aging process in two lines of mice selected divergently for body weight. As a result of long-term selection, the mice from two lines varied significantly in body weight during their life span. The differences regarded maturation rate, the length of the life time, reproduction performance, and fertility. Females from the light line (L) were fertile for a longer period of time than those from the heavy line (C), while the process of spermatogenesis disappearance started earlier in the light males than in the heavy ones. There were also differences in the relative weight of adrenal glands and histopathological changes connected with the hyperplasia of their spindle cells. The adrenal glands in females from both lines were heavier than in males. A significantly higher percentage of the cortex cell hyperplasia was observed in adrenals of mice from the C line than the L line. The differences were also scored between mice from the selection lines in relation to the length of their life. On average, the L mice lived 30 days longer than the heavy ones. Body weight loss was observed earlier in the old heavy males than the L ones and this was correlated with the earlier mortality in this group of animals.

Neuroendocrine and immunocytochemical demonstrations of decreased hypothalamo-pituitary-adrenal axis responsiveness to restraint stress after long-term social isolation.

We have studied the effects of long-term social isolation of male Wistar rats, after early weaning (16 days), on the activity of the hypothalamo-pituitary-adrenal (HPA) axis. In addition to studying basal HPA activity, the response of the HPA axis to 15 min of immobilization stress was examined. Plasma corticosterone concentrations were measured, and the relative weights of adrenal glands, thymus, and testes were obtained, the latter to check whether gonadal function was affected by the isolation paradigm. Moreover, we carried out a quantitative immunohistochemical study of pituitary ACTH and its hypothalamic secretagogues: CRF, arginine vasopressin (AVP), and oxytocin (OT), both at the level of the synthesizing cell bodies in the hypothalamic paraventricular nucleus and of the releasing fibers in the median eminence (ME). Body weight and daily consumption of food and water were not altered, but social isolation caused a reduction in plasma corticosterone levels, both under basal and stress-stimulated conditions; this was correlated with an increased thymus weight, without affecting adrenal or testicular weights. The immunohistochemical study revealed that isolation caused a smaller increase in the number of ACTH-immunoreactive cells in the pars distalis of the anterior pituitary after exposure to restraint stress, as compared with control animals. This result indicates that fewer corticotrophs were activated by restraint stress in isolated animals, such cells being smaller and exhibiting a smaller ACTH-immunoreactive area than in control animals. Isolated animals also showed an increase in the content of CRF-ir fibers in the ME and a smaller decrease in the neuropeptide immunoreactivity after stress than that observed in control animals. This result could indicate a reduced release of CRF into the portal vasculature in response to acute stress and may partially explain the reduced activation of corticotrophs observed in the pituitary of isolated animals. However, no changes were found in the content of CRF, AVP, or OT within the paraventricular nucleus, nor of the AVP or OT content in the ME. The results of this study show that long-term social isolation after early weaning caused a hypofunction of the HPA axis in the adult rat. This hypofunction was particularly evident after exposure to an acute stressor, suggesting a desensitization of this axis to stressful stimuli.

The effect of clenbuterol on adrenal function in rats.

The use of anabolic agents is illegal in the European Community but the effect of these agents on animal welfare is not well documented. The aim of this study was to evaluate whether the administration of anabolic agents, such as clenbuterol, causes stressful effects in rats, as reflected by the adrenal function. Anabolic doses of clenbuterol (1 mg kg-1, 99% purity) were administered orally by stomach tube daily for 45 d to female Long Evans rats (250-300 g, n = 50). Twenty-five animals were used as controls. Blood samples were collected from the jugular vein in anaesthetised animals (ketamine and xylazine). At the end of the experiment, the animals were sacrificed and the adrenal glands were removed. Hormonal levels were measured by an enzyme immunoassay previously validated for this species. Hormonal levels of cortisol and corticosterone, and histopathological analysis, were used as indicators of the adrenal function. Increased corticosterone and cortisol secretion was found in the treated group (p < 0.001), both in adrenal homogenates and peripheral blood samples, compared with control animals. Higher relative adrenal gland weight (adrenal gland-to-body weight ratio) was also found in the treated group (p < 0.01). The major histopathological finding was the presence of hyperplasia in the adrenocortical cells. It was concluded that the administration of an anabolic dose of clenbuterol causes a hyperstimulation of adrenal gland secretion that could adversely affect animal welfare.

Activity of the Hypothalamic-Pituitary-Adrenal Axis is Elevated in Rats with Activity-Based Anorexia

Activity-based anorexia is characterized by suppressed food intake and excessive physical activity. These behaviors are typical of persons with anorexia nervosa. Activity of the hypothalamic-pituitary-adrenal axis is known to be elevated in anorexia nervosa. We investigated the status of this axis in activity-based anorexia. Meal fed-control (MFC) and meal fed-wheel running (MFWR) rats were given access to food for 90 min daily; MFWR animals were allowed access to an activity wheel the remainder of the day. The experiment terminated when MFWR animals reached 75% of preexperimental body weight (males 3.9 +/- 0.3 d; females 4.2 +/- 0.2 d). Male and female MFWR rats consumed less food than MFC animals, while maintaining a high level of wheel running. Corticosterone concentrations were significantly elevated in MFWR animals. Corticotropin-releasing hormone mRNA concentrations in the paraventricular nucleus were not different. Relative adrenal gland weights were greater and thymus gland weights were lower in MFWR animals. Changes in food intake could not be explained by differences in insulin, glucose, beta-hydroxybutyrate or norepinephrine concentrations. Our results suggest increased activity of the hypothalamic-pituitary-adrenal axis in activity-based anorexia.

Study on effects of feeding laying hens on separate mycotoxins (aflatoxins, patulin, or citrinin)-contaminated diets on the egg quality and tissue constituents

Four groups (each of 8 laying hens plus one cock) were offered commercial laying mash contaminated with 100 ppb of aflatoxins, citrinin, patulin or uncontaminated (control) for 6 weeks. The mycotoxin-contaminated diets led to some significant changes in egg characteristics and composition such as ash and calcium contents of the egg shell. The noticeable changes including also the relative weights of adrenal glands. Blood profile reflected too alterations (P greater than 0.05) in urea content and activity of both glutamic oxaloacetic transaminase and alkaline phosphatase as well. The mycotoxins affected significantly moisture and fat contents of the red muscle and protein content, texture and percentage of lean meat in both types of muscles (red and white). Patulin toxicosis was responsible for the strongest alterations in moisture, fat and vitamin A contents of the laying hen's liver and for the lowest calcium content of egg shell besides the shape alteration of the eggs. Laying hens fed on aflatoxin-contaminated diet produced hatched chicks with higher weight (P less than or equal to 0.05) than those from the controls. Citrinin residues were 10 ppb in the fresh muscles and egg yolk and 6 ppb in egg white.

Weight and ascorbic acid content of the adrenal glands in pigs

The weight and ascorbic acid (AA) content of the adrenal glands was measured in pigs with carcase weights ranging from about 10 to 100 kg. Appropriate conditions for the removal and storage of glands without loss of AA were also investigated. No AA was lost from adrenals kept at 4 degrees C for 24 hours after removal and frozen glands could be stored for six weeks at -14 degrees C with no loss of AA. Resting in lairage for 16 hours before slaughter was sufficient time to allow recovery of adrenal AA depleted by stress. No significant differences were found between Large White and Large White cross Landrace pigs for adrenal weight or AA content, however, the pure bred animals tended to have slightly lighter adrenals. In 86.2 per cent of pigs the left gland was heavier than the right and on average left glands were 10.9 per cent heavier. AA concentration was 5.6 per cent higher in the right glands. The concentration of AA remained more or less constant with increasing body size while the relative adrenal gland weight decreased.

Effects of divided feeding on activity-stress ulcer and the thymus weight in the rat

Rats housed in running-wheel activity cages and fed 1 hr or 2 hr daily exhibited excessive running and subsequently died revealing large stomach ulcers, reduced absolute thymus weight, and an increase in relative weight of adrenal glands. However, two 0.5-hr or two 1-hr daily feedings did significantly reduce ulcer incidence. Control rats for the four feeding schedules did not die, were ulcer free, and did not exhibit the changes in thymus and adrenal weight observed in exprimental rats. These results suggest that the divided daily feeding schedule ameliorates the ulcerogenic and immune processes in activity-stress rats.

Studies on the Sodium Requirement of Growing Japanese Quail

The response of Japanese quail, fed a purified diet, to dietary increments of sodium chloride was studied. Birds fed the basal diet (0.042-0.051% sodium) displayed poor growth, high mortality, depressed plasma sodium levels, elevated blood hematocrit and increased relative adrenal gland weights. Growth plateaued and the other parameters reached normal values at a total dietary sodium level of approximately 0.10 percent.

Adrenal weights in relation to reproductive status in the pika, Ochotona princeps (Richardson).

Relative weights of adrenal glands (mg per 100 g body wt.) of 301 pikas from southwestern Alberta were examined in relation to season, sex, age, and reproductive status. Significant enlargement of adrenal glands was found only in adult females and was associated with pregnancy and lactation.