Publications

Thermogenic brown and beige adipocytes convert chemical energy to heat by metabolizing glucose and lipids. Serotonin (5-HT) neurons in the CNS are essential for thermoregulation and accordingly may control metabolic activity of thermogenic fat. To test this, we generated mice in which the human diphtheria toxin receptor (DTR) was selectively expressed in central 5-HT neurons. Treatment with diphtheria toxin (DT) eliminated 5-HT neurons and caused loss of thermoregulation, brown adipose tissue (BAT) steatosis, and a >50% decrease in uncoupling protein 1 (Ucp1) expression in BAT and inguinal white adipose tissue (WAT). In parallel, blood glucose increased 3.5-fold, free fatty acids 13.4-fold, and triglycerides 6.5-fold. Similar BAT and beige fat defects occurred in Lmx1b(f/f)ePet1(Cre) mice in which 5-HT neurons fail to develop in utero. We conclude 5-HT neurons play a major role in regulating glucose and lipid homeostasis, in part through recruitment and metabolic activation of brown and beige adipocytes.

Oligodendroglioma is one of the most common primary central nervous system neoplasms of dogs. It is often diagnosed in older, brachycephalic breeds, and although its typical clinical features and neuroanatomic location have been well described, less common presentations may hinder its diagnosis. We describe 3 cases of canine cerebral oligodendroglioma that clinically and grossly present as intraventricular tumors. Histologic findings in all cases were typical of oligodendroglioma. Neoplastic cells were uniformly immunoreactive for Olig2 and negative for neuron-specific enolase, neurofilament, and glial fibrillary acidic protein. In addition to the immunopositivity for Olig2, a cluster of morphologically distinct neoplastic cells in one of the cases was immunoreactive for synaptophysin, and the case was diagnosed as an oligodendroglioma with neurocytic differentiation. Based on these findings, oligodendroglioma should be included as a differential diagnosis for intraventricular neoplasia in dogs. Furthermore, oligodendroglioma with ventricular involvement should be differentiated from central neurocytoma by immunohistochemistry.