A new group housing approach for non-human primate metabolism studies.

Understanding the absorption, distribution, metabolism and excretion (ADME) of candidate drugs in preclinical species is an integral part of the safety and efficacy evaluation in drug development. For this purpose, the housing of single animals in metabolism cages has historically been common practice for ADME studies. Whilst mini-pigs and dogs are selected wherever possible, non-human primates (NHPs) are used where there is no suitable scientific alternative. Having undergone only minimal revisions over the past 30 years, the traditional single-housing metabolism cage design for NHPs significantly limits normal vertical movement and social behaviours in primates. Minimising animal suffering and improving welfare is an important aspect of working with animals in research and Novo Nordisk A/S, together with collaborators, has focused on this area for many years. A novel metabolism cage for group housing of NHPs has been designed in a joint collaboration between Novo Nordisk A/S and Covance Inc. The advantages of this novel cage are extensive, including a significantly increased cage volume and ability for socialisation, as well as improvements to alleviate stress and boredom. The excretion balance data from six male NHPs housed in single or group metabolism cages were compared using the radiolabelled test compound [14C]-quetiapine. Welfare, in terms of stress and behaviour, when animals were single or group housed was also assessed. Mean recoveries of radioactivity were shown to be comparable irrespective of housing design (83.2% for group-housed animals vs. 87.1% for single-housed animals), supporting the potential suitability of NHP group housing for future metabolism ADME studies.

A novel welfare and scientific approach to conducting dog metabolism studies allowing dogs to be pair housed.

Metabolism cages are designed to conduct absorption, distribution, metabolism and excretion (ADME) studies, enabling an 'excretion balance' scientific objective to be met. Historically, the design of dog metabolism cages has involved single housing. This type of housing has limitations for normal social behaviours and has been largely unchanged for 25-30 years. Improving animal welfare is a focus area for the authorities as well as the industry throughout the European Union. A collaboration was developed between Novo Nordisk and Covance to enhance the design of metabolism cages, allowing dogs to be pair housed. The purpose of the study was to compare excretion balance data from pair-housed and singly housed dogs in order to demonstrate that conducting excretion balance studies with a pair-housing design improves animal welfare without compromising the scientific integrity of the study. A radiolabelled test compound, [14C]-Quetiapine, was selected for this investigation based on its excretion profile. The assessment of the dogs' stress levels was investigated by measuring the levels of serum cortisol as an indicative biomarker. Results were inconclusive due to large variations in cortisol levels. However, dogs appeared calmer in the pair-housing setting. The overall mean recovery (±standard deviation) for pair-housed animals (94.0 ± 0.66% of the dose) was equivalent to that from singly housed dogs (93.0 ± 2.29%). Based on these data, we conclude that pair housing of dogs for future metabolism ADME studies does not compromise the scientific integrity, and therefore is a major progression in the design of these studies, enhancing welfare.

Measurement of ring A-reduced progesterone metabolites by enzyme-linked immunoassay with colorimetric detection: baseline levels of six metabolites, including pregnanolone, in male rat plasma.

The performance of an antiserum to progesterone and pregnane neurosteroids was assessed in two competitive assay setups: radioimmunoassay and enzyme-linked immunoassay with colorimetric detection, both with the same limit of detection of 2 pg. The enzyme-linked immunoassay was less labor-intensive and had better precision of measurement and was used to measure progesterone and six of its ring A-reduced metabolites in rat plasma. The measured levels of allopregnanolone and progesterone were in agreement with those reported previously when measured by gas chromatography/mass spectrometry and high-performance liquid chromatography coupled with radioimmunoassay and substantially lower than those previously measured by radioimmunoassay without chromatographic separation. Both isomers of dihydroprogesterone and all four isomers of pregnanolone were detected in rat plasma, indicating that progesterone is metabolized by reduction at the C5 and C3 position of the A ring, in both alpha and beta configurations. In addition to 5beta-dihydroprogesterone and isopregnanolone, which have not been previously detected in the rat, we found considerable amounts of pregnanolone, which is neuroactive, with similar potency to that of allopregnanolone but was previously thought not to be produced in rats.

Alcohols which have been in contact with any plastics may interfere in radioimmunoassays of progesterone.

In recent years there has been increasing use of plastic rather than glass containers for many liquids, including wine. However we have found that residue from commercially obtained 'pure' ethanol dispensed in plastic bottles interferes in some biochemical assays. We have observed a volume-dependent decrease in maximally bound ligand in radioimmunoassays of progesterone. The resulting shift in the standard curve leads to an underestimation of the analyte concentrations and to altered estimation of cross reactivity by competing ligands. These effects became apparent in assays with high sensitivity (500 pg or less). All sources of ethanol obtainable in Quebec contained impurities. A similar effect was also produced by 'pure' methanol. The reduction in maximally bound ligand was amplified when the alcohol was aliquoted using plastic pipette tips. We conclude that alcohols which have had any contact with plastics are not safe to use in immunoassays of progesterone (or its metabolites as estimated according to cross-reactivity after HPLC) and may affect other assays. If the use of alcohol and plastic tips cannot be avoided, the amount of alcohol used should be reduced to 1% or less. This can be accomplished by preparing steroid standards in assay buffers containing albumin or gelatin, which enhance the solubility of steroids in aqueous media.

Antinociceptive profile of ring A-reduced progesterone metabolites in the formalin test.

The present study investigated the effect of acute systemic administration of six progesterone metabolites on formalin-induced pain in the rat. The 3alpha-hydroxylated metabolites allopregnanolone and pregnanolone are highly potent positive modulators at the GABA(A) receptor and produced a biphasic effect on pain in the formalin test. Dose-dependent antinociception was observed at lower doses (maximal antinociception at 0.16mg/kg) and was reversed at higher doses. Bicuculline abolished the antinociceptive effect. The 3beta-hydroxylated epipregnanolone and isopregnanolone are inactive or only weekly active at the GABA(A) receptor, and did not affect formalin-induced pain. 5alpha- and 5beta-dihydroprogesterone have also been shown to have low affinity for the GABA(A) receptor, but can be rapidly metabolized to their 3alpha-hydroxylated counterparts. In the formalin test, they produced a biphasic effect on pain similar to that of pregnanolone and allopregnanolone, but with lower potency. The effect was reversible by bicuculline, showing involvement of the GABA(A) receptor, and was blocked by indomethacin, implying that the antinociceptive effect is dependent on their conversion to allopregnanolone or pregnanolone. The results indicate that GABA-ergic progesterone metabolites modulate nociception. A change in levels of GABA-ergic progesterone metabolites, such as is observed in depression, chronic fatigue and premenstrual dysphoric disorder could, therefore, contribute to the pain complaints associated with these disorders.

A case of seasonal bipolar disorder exacerbated by Cushing's disease.

While depression is common in Cushing's syndrome from whatever cause (pituitary, adrenal, or ectopic adrenocorticotropic hormone-secreting tumor or hyperplasia, or exogenous administration of glucocorticoids) and hypercortisolemia is prevalent in major depression, any association between seasonal affective disorder and Cushing's syndrome is unknown. We present a case of seasonal bipolar disorder, gradually worsening for more than 9 years (1985-1994), accompanied by increasing osteoporosis, mild weight gain, and slight truncal obesity in a middle-aged woman. In January 1991, her seasonal affective disorder was successfully treated with light therapy, but in the following year, bipolar mood swings with a seasonal pattern emerged, which were refractory to light therapy and antidepressants but responsive to lithium. In August 1992, she became depressed despite a 1500-mg lithium daily dosage along with light therapy, and, in 1993, a diagnosis of Cushing's disease (Cushing's syndrome as a result of a pituitary adrenocorticotropic hormone-secreting tumor) was made. The pituitary tumor was removed in February 1994, and pituitary function was fully restored by 1996. While the symptoms of Cushing's syndrome subsided, her bipolar illness continued to require maintenance treatment with low doses of lithium but did not require light therapy.

An introduction to anorexia nervosa and bulimia nervosa.

Nurses may come into contact with patients who have anorexia nervosa and bulimia nervosa. The authors discuss the signs and symptoms of these illnesses and outline treatment options for patients with eating disorders.