Tyrosine hydroxylase activity in the endocrine pancreas: changes induced by short-term dietary manipulation

BACKGROUND: Tyrosine hydroxylase (TH) activity and its possible participation in the control of insulin secretion were studied in pancreatic islets of adult Wistar rats fed a standard commercial diet (SD) or carbohydrates alone (CHD) for one week. TH activity, norepinephrine (NE) content, and glucose-induced insulin secretion were assessed. Blood glucose and insulin levels were measured at the time of sacrifice. RESULTS: CHD rats had significantly higher blood glucose and lower insulin levels than SD rats (114.5 ± 6.7 vs 80.7 ± 7.25 mg/dl, p < 0.001; 20.25 ± 2.45 vs 42.5 ± 4.99 μU/ml, p < 0.01, respectively). Whereas TH activity was significantly higher in CHD isolated islets (600 ± 60 vs 330 ± 40 pmol/mg protein/h; p < 0.001), NE content was significantly lower (18 ± 1 vs 31 ± 5 pmol/mg protein), suggesting that TH activity would be inhibited by the end-products of catecholamines (CAs) biosynthetic pathway. A similar TH activity was found in control and solarectomized rats (330 ± 40 vs 300 ± 80 pmol/mg protein/h), suggesting an endogenous rather than a neural origin of TH activity. CHD islets released significantly less insulin in response to glucose than SD islets (7.4 ± 0.9 vs 11.4 ± 1.1 ng/islet/h; p < 0.02). CONCLUSIONS: TH activity is present in islet cells; dietary manipulation simultaneously induces an increase in this activity together with a decrease in glucose-induced insulin secretion in rat islets. TH activity – and the consequent endogenous CAs turnover – would participate in the paracrine control of insulin secretion

Racial, Ethnic and Gender Inequities in Farmland Ownership and Farming in the US

This paper provides an analysis of U.S. farmland owners, operators, and workers by race, ethnicity, and gender. We first review the intersection between racialized and gendered capitalism and farmland ownership and farming in the United States. Then we analyze data from the 2014 Tenure and Ownership Agricultural Land survey, the 2012 Census of Agriculture, and the 2013–2014 National Agricultural Worker Survey to demonstrate that significant nation-wide disparities in farming by race, ethnicity and gender persist in the U.S. In 2012–2014, White people owned 98% and operated 94% of all farmland. They generated 98% of all farm-related income from land ownership and 97% of income from farm owner-operatorship. Meanwhile, People of Color farmers (African American or Black, Asian American, Native American, Hawaiian or other Pacific Islander, and Hispanic farmers) were more likely to be tenants rather than owners, owned less land, and generated less farm-related wealth per person than their White counterparts. Hispanic farmers were also disproportionately farm laborers. In addition to racial and ethnic disparities, there were disparities by gender. About 63% of non-operating landowners, 86% of farm operators, and 87% of tenant farmers were male, and female farmers tended to generate less income per farmer than men. This data provides evidence of ongoing racial, ethnic and gender disparities in agriculture in the United States. We conclude with a call to address the structural drivers of the disparities and with recommendations for better data collection