We studied the time-dependent changes in the response of heart rate (sinus cycle length) to 30-second trains of vagal stimulation (8 Hz), repeated every 2 minutes, in canine neonates aged 7.1 +/- 2.5 (mean +/- SD) days. The first vagal train prolonged the sinus cycle length by 58 +/- 35%, but the response was attenuated during subsequent trains (98 +/- 5% inhibition of the vagal response after ...

Neuropeptide Y and norepinephrine are localized in sympathetic nerve terminals throughout the heart. We sought to determine the functional distribution of the neuropeptide Y-containing sympathetic fibers to the sinus and atrioventricular (AV) nodal regions. We recorded cycle length, AV interval, and arterial pressure in 14 anesthetized dogs. We assessed the release of neuropeptide Y from sympat...

Leptin binds to receptors in multiple hypothalamic nuclei to increase sympathetic nerve activity; however, the neurocircuitry is unclear. Here, using anesthetized male Sprague-Dawley rats, we investigated the role of the paraventricular nucleus of the hypothalamus. Intracerebroventricular injection of leptin slowly increased lumbar sympathetic nerve activity (LSNA), heart rate, mean arterial pr...

Background. Myocardial adrenergic neurotransmitters and j-adrenergic receptor levels were measured in left and right ventricular myocardial specimens obtained from 30 patients with biventricular failure resulting from idiopathic dilated cardiomyopathy. Methods and Results. Nonfailing myocardium obtained from 12 organ donors provided control data. Norepinephrine, dopamine, and neuropeptide Y con...

Neuropeptide Y is stored in sympathetic nerve terminals throughout the heart and has direct and indirect effects on cardiac function. Although neuropeptide Y has been shown to be released upon intense (16-30 Hz) cardiac sympathetic stimulation, we sought to determine whether effective quantities of neuropeptide Y were released from cardiac sympathetic neurons under more natural conditions. We r...

Sleep is important for maintenance of normal physiology in animals. In mammals, neuropeptide Y (NPY), a homolog of Drosophila neuropeptide F (NPF), is involved in sleep regulation, with different effects in human and rat. However, the function of NPF on sleep in Drosophila melanogaster has not yet been described. In this study, we investigated the effects of NPF and its receptor-neuropeptide F ...

Feeding is a complex behavior that is regulated by several internal mechanisms. Neuropeptides are able to survey quantities of stored energy and inform the organism if nutrient intake is required. In addition to this homeostatic regulation, a post-feeding reward system positively reinforces feeding. Slight adjustments to either system can tilt the balance to affect the energy reserves and survi...

Circadian or daily rhythms generated from the mammalian suprachiasmatic nuclei (SCN) of the hypothalamus can be synchronized by light and nonphotic stimuli. Whereas glutamate mediates photic information, nonphotic information can in some cases be mediated by neuropeptide Y (NPY) or serotonin. NPY or serotonin can reduce the phase-resetting effect of light or glutamate; however, the mechanisms a...

Neuropeptide transmitters are synthesized throughout the CNS and play important modulatory roles. After synthesis in the neuronal cell body, it is generally assumed that peptides are transported to nonspecialized sites of release. However, apart from a few cases, this scenario has not been thoroughly examined. Using wild-type and NPY(GFP) transgenic mice, we have studied the subcellular distrib...

Neuropeptide Y (NPY) is a ubiquitous endocrine neuropeptide found in vertebrate and invertebrate. In our present work, two NPY-like exocrine conopeptides (designated as cono-NPYs) were first identified in the venom of cone snails. Both cono-NPYs showed sequence characteristics of invertebrate NPYs, suggesting that some exocrine venom peptides are probably evolved from the preexisting endocrine ...