Prenatal cocaine administration stimulates fetal brain tyrosine hydroxylase activity.

Functional effects of prenatal cocaine exposure may be mediated in part by changes in catecholaminergic development. The present study examined whether cocaine administration influenced fetal brain activity of tyrosine hydroxylase (TH), the rate-limiting enzyme in catecholamine biosynthesis. Subcutaneous (s.c.) injection of pregnant rats with 40 mg/kg of cocaine HCl daily from gestational day (GD) 8 to GD20 resulted in an 8.7% stimulation of fetal whole-brain TH activity compared to controls. We then switched to a s.c. implantation procedure involving Silastic capsules filled with 80 mg of cocaine base dissolved in polyethylene glycol (PEG). Implantation of 2 such capsules on GD18 produced a 28% increase in fetal TH activity measured only 3 days later on GD21. Subsequent experiments demonstrated that GD14 implantation was equally effective in stimulating fetal TH activity on GD17, but that the enzyme was unaffected in the brains of the treated dams. When cocaine-containing capsules were implanted on GD18, removed on GD21, and the females were allowed to deliver normally, offspring TH activity was still elevated on postnatal day 10 but not later. Finally, the presence of cocaine implants from GD18 to GD21 had no influence on fetal brain neurotransmitter and metabolite concentrations, however, the treated dams exhibited significant reductions in dopamine (DA) and the serotonin metabolite, 5-hydroxyindoleacetic acid. We conclude that maternal cocaine implants rapidly but transiently stimulate TH activity in the fetal brain, and that such stimulation prevented the DA depletion observed in the dams.

Cerebral infarction in POEMS syndrome: incidence, risk factors, and imaging characteristics.

OBJECTIVES: To determine the risk factors and incidence of cerebral infarction associated with POEMS (polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes) syndrome. METHODS: The Mayo Clinic dysproteinemia database was queried to identify patients with coded diagnosis of POEMS syndrome. Patients with cerebral infarction, occurring after the onset of POEMS-related symptoms, were selected. A retrospective observational study design was used to evaluate potential predictors of stroke in patients with POEMS syndrome. RESULTS: A total of 9 patients (10%; 95% confidence interval 5.4-17.9) with cerebral infarction were identified (2 women, 22%). Traditional stroke risk factors were not significantly different between the stroke and nonstroke subgroups, but hematologic abnormalities such as elevated platelet count and bone marrow plasmacytosis differed between the 2 groups. Cerebral infarction occurrence after successful treatment of the underlying condition was not observed. CT and MRI data demonstrated a wide spectrum of infarct topography in these patients. Common stroke etiologies comprised suspected vascular structural abnormalities leading to vessel dissection and stenosis, in addition to embolism from a proximal source. CONCLUSIONS: The 5-year risk of cerebral infarction in patients with POEMS syndrome is 13.4%. Evidence of plasma cell proliferation within the bone marrow and elevated serum platelet count led to increased risk of cerebral infarction in this population. We conclude that known modifiable stroke risk factors should be aggressively managed. Treatment of thrombocytosis should be considered in patients without a contraindication. Treatment of the syndrome may be the best approach to decreasing risk of cerebral infarction in these patients.