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Insulin acts in the brain to suppress feeding, whereas neuropeptide Y (NPY) has the opposite effect. Since fasting lowers plasma insulin levels and increases hypothalamic synthesis of NPY, we proposed that insulin may inhibit hypothalamic NPY gene expression. To test this hypothesis, we used RIA and in situ hybridization histochemistry to determine if(More)
The hormones insulin, leptin, and ghrelin have been demonstrated to act in the central nervous system (CNS) as regulators of energy homeostasis, acting at medial hypothalamic sites. Here, we summarize research demonstrating that, in addition to direct homeostatic actions at the hypothalamus, CNS circuitry that subserves reward and is also a direct and(More)
To test the hypothesis that diabetic hyperphagia results from insulin deficiency in the brain, diabetic rats (streptozotocin-induced) were given an intracerebroventricular (ICV) infusion of saline or insulin (at a dose that did not affect plasma glucose levels) for 6 days. Food and water intake were significantly increased in diabetic rats, but only food(More)
By acting in the brain, insulin suppresses food intake, whereas neuropeptide Y (NPY) has the opposite effect. Since fasting increases NPY gene expression in the hypothalamic arcuate nucleus (ARC) and also lowers circulating insulin levels, we hypothesized that the anorexiant effect of insulin could result from insulin inhibition of NPY gene transcription in(More)
Extensive historical evidence from the drug abuse literature has provided support for the concept that there is functional communication between central nervous system (CNS) circuitries which subserve reward/motivation, and the regulation of energy homeostasis. This concept is substantiated by recent studies that map anatomical pathways, or which(More)
IRS-1 is phosphorylated on tyrosine residues after insulin stimulation and participates in the early events of signal transduction in peripheral insulin-sensitive tissues. This study determined whether neuronal populations in the rat olfactory bulb and hippocampus (brain regions which have very high concentrations of insulin receptors) also express IRS-1(More)
To characterize the relationship between insulin levels in plasma and those in cerebrospinal fluid (CSF), we studied the kinetics of both the uptake of insulin into CSF from plasma and the turnover of insulin within the CSF compartment. Sustained physiological levels of euglycemic hyperinsulinemia (plasma insulin approximately 500 pM) did not alter CSF(More)
The authors hypothesized that insulin and leptin, hormones that convey metabolic and energy balance status to the central nervous system (CNS), decrease the reward value of food, as assessed by conditioned place preference (CPP). CPP to high-fat diet was blocked in ad-lib fed rats given intraventricular insulin or leptin throughout training and test or(More)
The effect of caloric deprivation to stimulate hypothalamic neuropeptide Y (NPY) gene expression is hypothesized to represent a physiologically important adaptation in body weight homeostasis. To evaluate the specificity of this response, we used in situ hybridization histochemistry to measure hypothalamic expression of mRNA encoding NPY, galanin, and the(More)
To study the route by which plasma insulin enters cerebrospinal fluid (CSF), the kinetics of uptake from plasma into cisternal CSF of both insulin and [14C]inulin were analyzed during intravenous infusion in anesthetized dogs. Four different mathematical models were used: three based on a two-compartment system (transport directly across the blood-CSF(More)