Modulatory neurotransmitters, including the histaminergic system, are essential in mediating cognitive functions affected in Alzheimer's disease (AD). The roles of disease genes associated with AD, most importantly the presenilin1 gene (psen1), are poorly understood. We studied the role of psen1 in plasticity of the brain histaminergic system using a novel psen1 mutant zebrafish, Danio rerio. W...

The need for increased sleep after traumatic brain injury is a common and disabling complaint, yet its etiology is unknown. Previous studies have demonstrated diffuse damage to various hypothalamic systems, but the integrity of the histaminergic tuberomammillary nucleus, a major arousal-promoting system located in the posterior hypothalamus, has never been examined in head trauma patients. Here...

Aim: The effect of orexin on wakefulness has been shown to be largely mediated by activation of histaminergic neurons via orexin receptor-2 (OX2R). Consistently, OX2R mRNA is abundantly expressed in histaminergic neurons in the tuberomammillary nucleus (TMN). However, orexin receptors in the other regions of the brain might also play important roles in maintenance of wakefulness. To dissect the...

We investigated whether histaminergic tone contributes to the seasonal catabolic state in Siberian hamsters by determining the effect of ablation of histaminergic neurons on food intake, metabolic rate and body weight. A ribosomal toxin (saporin) conjugated to orexin-B was infused into the ventral tuberomammillary region of the hypothalamus, since most histaminergic neurons express orexin recep...

En bloc immunohistochemistry was used to examine the distribution of L-histidine decarboxylase (HDC)-immunoreactive neurons on the ventral surface of the rat hypothalamus. Following standard paraformaldehyde fixation, the ventral hypothalamus containing the tuber cinereum was carefully dissected free and incubated en bloc with antisera to HDC followed by standard avidin-biotin complex immunohis...

We investigated the effects of the central histaminergic system on afferent sensory signals in the retinogeniculocortical pathway in the intact brain. Extracellular physiological recordings in vivo were obtained from neurons in the cat dorsal lateral geniculate nucleus (LGN) in conjunction with electrical activation of the histamine-containing cells in the tuberomammillary nucleus of the hypoth...

The hypothalamus plays a major integrative role in the homeostasis of a variety of physiological processes, including sleep and waking. The preoptic area of the anterior hypothalamus (POAH) and the tuberomammillary nuclei (TMN) of the posterior hypothalamus (PH) interact to form part of an intrahypothalamic sleep/wake control system (1-6). For example, Υ-aminobutyric acid (GABA)-containing neur...

We have demonstrated previously the importance of histaminergic neurons in arousal mechanisms. In addition to their ascending axons, these neurons also send heavy descending inputs to the mesopontine tegmentum (MPT), which plays a key role in cortical activation during wakefulness (W). This anatomical link suggests histaminergic control of the mechanisms of the MPT relevant to behavioral states...

In spite of the initial and pivotal findings that the newly identified neuropeptide S (NPS) promotes arousal associated with locomotor and anxiolytic-like effects, the mechanisms through which NPS acts to modulate sleep-waking states remain unclear. The present study was undertaken to investigate in the rat the effects of i.c.v. injection of NPS on the EEG, sleep-wake cycle, and brain c-Fos exp...