RETROSPECTIVE EVALUATION OF HEPATOCELLULAR NEOPLASMS IN NILE LECHWE (KOBUS MEGACEROS) FROM TWO FLORIDA ZOOLOGICAL INSTITUTIONS.

This case series describes hepatocellular neoplasms in 10 Nile lechwe (Kobus megaceros) at two separate zoological institutions in Florida. Histologically, the neoplasms were classified as hepatocellular carcinoma (n = 7), hepatocellular adenoma (n = 2), and hepatobiliary carcinoma (n = 1). Common clinical signs were nonspecific and included thin body condition (n =7), lethargy (n =6), lameness (n =3), and acute recumbency (n =5). Four males and six females were affected, and the mean age at death was 12.7 yr with a range of 4-18 yr. All cases were diagnosed postmortem, and metastasis to various sites, including lung, lymph nodes, and omentum, was found in 40% of cases (n = 4). A single case of hepatocellular carcinoma in a Nile lechwe was described in 2007; however, this is the first reported series of neoplasms in Reduncinae. The pathogenesis behind the development of hepatocellular neoplasms in Nile lechwe has not yet been identified.

Seasonal decrease in thermogenesis and increase in vasoconstriction explain seasonal response to N6 -cyclohexyladenosine-induced hibernation in the Arctic ground squirrel (Urocitellus parryii).

Hibernation is a seasonal phenomenon characterized by a drop in metabolic rate and body temperature. Adenosine A1 receptor agonists promote hibernation in different mammalian species, and the understanding of the mechanism inducing hibernation will inform clinical strategies to manipulate metabolic demand that are fundamental to conditions such as obesity, metabolic syndrome, and therapeutic hypothermia. Adenosine A1 receptor agonist-induced hibernation in Arctic ground squirrels is regulated by an endogenous circannual (seasonal) rhythm. This study aims to identify the neuronal mechanism underlying the seasonal difference in response to the adenosine A1 receptor agonist. Arctic ground squirrels were implanted with body temperature transmitters and housed at constant ambient temperature (2°C) and light cycle (4L:20D). We administered CHA (N6 -cyclohexyladenosine), an adenosine A1 receptor agonist in euthermic-summer phenotype and euthermic-winter phenotype and used cFos and phenotypic immunoreactivity to identify cell groups affected by season and treatment. We observed lower core and subcutaneous temperature in winter animals and CHA produced a hibernation-like response in winter, but not in summer. cFos-ir was greater in the median preoptic nucleus and the raphe pallidus in summer after CHA. CHA administration also resulted in enhanced cFos-ir in the nucleus tractus solitarius and decreased cFos-ir in the tuberomammillary nucleus in both seasons. In winter, cFos-ir was greater in the supraoptic nucleus and lower in the raphe pallidus than in summer. The seasonal decrease in the thermogenic response to CHA and the seasonal increase in vasoconstriction, assessed by subcutaneous temperature, reflect the endogenous seasonal modulation of the thermoregulatory systems necessary for CHA-induced hibernation. Cover Image for this issue: doi: 10.1111/jnc.14528.