A cafeteria‐style diet induces obesity and increases lumbar sympathetic nerve activity in rats

Abstract

Obesity is a primary cause of essential hypertension. Despite the importance of this link, little is known about how weight gain causes increases in arterial blood pressure (BP). A leading hypothesis suggests that obesity may activate long‐term elevations in sympathetic nerve activity (SNA) that increase peripheral resistance. We therefore predicted that a cafeteria‐style diet would chronically increase body weight and lumbar SNA in rats. To test this, we implanted Telemetry Research (Auckland, New Zealand) radio‐telemetry devices into female Wistar rats. Starting at 5 days following surgery, rats were divided into a Control group (n = 4) that received rat chow and water for 16 days and a Cafeteria group (n = 3) that received crackers, vanilla wafers, buttered popcorn, cheetos, chocolate, salami, smoked fish, condensed milk, and soda pop also for 16 days. At study completion, body weight gains were lower in Controls (from 257±21g to 284±16 g) than in Cafeteria (from 254±21 g to 306±28 g) rats. Whereas lumbar SNA remained at baseline levels in Control rats after 16 days, it increased by 20% in Cafeteria‐fed rats. A testing of lumbar SNA quality revealed that the nerves responded appropriately to sodium nitroprusside (from 100% baseline to 128±14%) and to hexamethonium bromide (100% to 16±6%). These data show, for the first time, that the high‐fat cafeteria‐style diet stimulates chronic increases in lumbar SNA in rats.