Possible role of afferent autonomic signals in abdominal organs in anorexic and cardiovascular responses to nicotine injection in rats.

Smoking generally causes an increase in nicotine levels in the blood, affecting the brain components, such as the hypothalamus (feeding-related area) or the brain stem (cardiovascular control area). In terms of nicotine transmission to the brain, a new insight that the afferent vagal nerve in the liver is important for sensing increased nicotine levels in the blood and informing the brain was reported in an experiment with rats. However, it has not been clarified whether the afferent autonomic nerve system is implicated in feeding and cardiovascular responses to nicotine.

L-Ornithine intake affects sympathetic nerve outflows and reduces body weight and food intake in rats.

Ingesting the amino acid l-ornithine effectively improves lipid metabolism in humans, although it is unknown whether it affects the activities of autonomic nerves that supply the peripheral organs related to lipid metabolism, such as adipose tissues. Thus, we investigated the effects of l-ornithine ingestion on autonomic nerves that innervate adipose tissues and the feeding behaviors of rats. Intragastric injection of l-ornithine (2.

Soy isoflavone affects the autonomic nervous system in a tissue-specific manner in anesthetized rats.

We examined and compared the effects of taste stimulation by soy saponin as well as soy isoflavone and intragastric (IG) injection of both on the autonomic nerve activities and feeding behavior in rats. We found that taste stimulation by soy saponin or soy isoflavone-rich solution (SIRS) did not affect the activity of the sympathetic nerve supplying the adrenal gland in urethane-anesthetized rats; however, IG injection of SIRS, but not soy saponin, stimulated the adrenal sympathetic nerve activity (ASNA) in a dose-dependent manner. Moreover, IG injection of SIRS significantly suppressed the activity of the vagus nerve innervating the stomach, whereas sympathetic nerve outflows to brown or white adipose tissue were not affected by IG injection of SIRS.

Effects of intragastric injection of glutamate on efferent sympathetic nerve activity in rats.

Niijima previously reported that intragastric infusion of glutamate has increased the activity of the efferent parasympathetic nerves that innervate the stomach and pancreas in urethane-anesthetized rats. In the present study, the effects of intragastric injection of glutamate on the efferent sympathetic nerve outflow to the kidney and the white adipose tissue in rats were analyzed. Although the sympathetic nerve activities of the renal and white adipose tissues were not affected after intragastric glutamate injection in rats that were fasted for 3h, these activities were significantly accelerated after intragastric glutamate injection in rats that were fasted for 48h.

Autonomic and cardiovascular effects of central neuromedin U in rats.

Previous studies have demonstrated that neuromedin U (NMU) affects cardiovascular functions such as blood pressure (BP) or heart rate (HR) in rats. Here, we examined the effects of the lateral cerebral ventricular (ICV) injection of various doses of NMU on renal sympathetic nerve activity (RSNA) and BP in urethane-anesthetized rats. ICV injection of NMU elevated RSNA, BP and HR in a dose-dependent manner.