Modeling spontaneous opioid withdrawal in male and female outbred mice using traditional endpoints and hyperalgesia.

Opioid withdrawal significantly impacts drug dependence cycles as hyperalgesia associated with withdrawal is often a reason for continued drug use. Animal models of addiction are important tools for studying how drug dependence and withdrawal impact not only normal neurocircuitry but also the effectiveness of potential treatments for dependence and withdrawal. We conducted a study of the time course of spontaneous morphine withdrawal in outbred male and female mice that can be used to examine sex differences in male and female mice using both traditional somatic endpoints and mechanical hyperalgesia as an endpoint of withdrawal. Male and female national institute of health (NIH) Swiss mice were made dependent upon morphine using an escalating dosing schedule. Injections were stopped after 5 days. Withdrawal behavior was assessed at time intervals up to 106 h after the final injection. Numbers of forepaw tremors, wet-dog shakes, jumps and other behaviors were scored to create a global score. Paw pressure readings were then also taken to track changes in sensitivity to a painful stimulus over time. Male and female mice had approximately similar withdrawal severity peaking at 24 h after the final injection as measured by composite global scores. Females did exhibit an earlier and greater frequency of tremors than males. Although males and females showed similar hyperalgesia during withdrawal, females recovered faster. Spontaneous opioid withdrawal peaking at 24 h was demonstrated in male and female NIH Swiss mice. We also successfully demonstrated that hyperalgesia is an endpoint that varies over the course of withdrawal.

An outbreak of congenital goiter and chondrodystrophy among calves born to spring-calving beef cows.

An outbreak of congenital diffuse hyperplastic goiter and chondrodystrophy occurred among springborn calves at an Angus-based cow-calf operation in southern Alberta. Although these diseases are observed globally in multiple species, reports of their occurrence concurrently are exceptionally rare. A nutritional cause is highly suspected as previous matings between the same sires and dams resulted in apparently normal calves. However, it is unclear if multiple mineral deficiencies manifested as goiter and chondrodystrophy independently or if a primary hypothyroidism inhibited normal fetal growth and skeletal development. This is apparently the first large-scale outbreak of concurrent congenital goiter and chondrodystrophy reported in calves.

Épidémie de goitre congénital et de chondrodystrophie chez des veaux nés de vaches de boucherie mettant bas au printemps. Une épidémie de cas de goitre hyperplastique diffus et de chondrodystrophie est survenue chez des veaux de l'année dans un établissement de vaches-veaux Angus dans le sud de l'Alberta. Bien que ces conditions soient observées globalement chez une multitude d'espèces, la description de leur présence de manière concomitante est exceptionnellement rare. Une cause nutritionnelle est hautement soupçonnée étant donné que des accouplements antérieurs entre les mêmes taureaux et vaches ont produit des veaux apparemment normaux. Toutefois, il n'est pas clair si des déficiences minérales multiples se sont manifestées par du goitre et de la chondrodystrophie de manière indépendante ou si un hypothyroïdisme primaire a inhibé la croissance foetale normale et le développement squelettique. Le cas présent serait apparemment la première épidémie d'envergure concomitante de goitre congénital et de chondrodystrophie rapportée chez des veaux.(Traduit par Dr Serge Messier).