OBJECTIVES The ventromedial hypothalamic nucleus (VMH) regulates energy homeostasis as well as social and emotional behaviors. Nearly all VMH neurons, including those in the sexually dimorphic ventrolateral VMH (VMHvl) subregion, release the excitatory neurotransmitter glutamate and use the vesicular glutamate transporter 2 (Vglut2). Here, we asked how glutamatergic signaling contributes to the...

Suppression of GABAergic neurotransmission in the ventromedial hypothalamus (VMH) is crucial for full activation of counterregulatory responses to hypoglycemia, and increased γ-aminobutyric acid (GABA) output contributes to counterregulatory failure in recurrently hypoglycemic (RH) and diabetic rats. The goal of this study was to establish whether lactate contributes to raising VMH GABA levels ...

OBJECTIVE-To determine whether alterations in counterregulatory responses to hypoglycemia through the modulation of ATP-sensitive K(+) channels (K(ATP) channels) in the ventromedial hypothalamus (VMH) are mediated by changes in GABAergic inhibitory tone in the VMH, we examined whether opening and closing K(ATP) channels in the VMH alter local GABA levels and whether the effects of modulating K(...

OBJECTIVE The counterregulatory response to insulin-induced hypoglycemia is mediated by the ventromedial hypothalamus (VMH), which contains specialized glucosensing neurons, many of which use glucokinase (GK) as the rate-limiting step in glucose's regulation of neuronal activity. Since conditions associated with increased VMH GK expression are associated with a blunted counterregulatory respons...

The ventromedial hypothalamic nucleus (VMH) plays an important role in the control of feeding and energy homeostasis. In contrast to other hypothalamic nuclei that are also known to regulate energy balance, there is a paucity of nucleus-specific marker genes for the VMH, limiting the application of molecular approaches for analyzing VMH information processing, function, and circuitry. Here, we ...

OBJECTIVE Norepinephrine is locally released into the ventromedial hypothalamus (VMH), a key brain glucose-sensing region in the response to hypoglycemia. As a result, this neurotransmitter may play a role in modulating counterregulatory responses. This study examines whether norepinephrine acts to promote glucose counterregulation via specific VMH β-adrenergic receptors (BAR). RESEARCH DESIG...

We have previously reported that a glucosensor integrating hormonal responses to hypoglycemia is located in the ventromedial hypothalamus (VMH) and that local VMH glucose perfusion blocks counterregulatory hormone responses. To determine whether the by-product of glucose metabolism, lactate, can function within the VMH as an alternative for glucose, we delivered lactate locally to the VMH, duri...

AIMS Hypoglycemia is a severe side effect of intensive insulin therapy. Recurrent hypoglycemia (RH) impairs the counter-regulatory response (CRR) which restores euglycemia. During hypoglycemia, ventromedial hypothalamus (VMH) production of nitric oxide (NO) and activation of its receptor soluble guanylyl cyclase (sGC) are critical for the CRR. Hypoglycemia also increases brain reactive oxygen s...

Studies examining the etiology of obesity often focus on the relationship between taste, overeating, and the developnlc~r. of obesity. One animal model often used to study obesity, rats with lesions of the ventromedial hypothalamus (VMH) , is popular because the degree of overeating and obesity in that animal is particularly sensitive to the taste qualities of the food the rat eats. The exagger...

To explore the pathophysiological significance of the obese (ob) gene product, leptin, in ventromedial hypothalamus (VMH)-lesioned rats, we examined the synthesis and secretion of leptin and its satiety effect in VMH-lesioned rats compared with those in sham-operated rats. Northern blot analysis revealed that ob gene expression is markedly augmented in the mesenteric and sc white adipose tissue...