Encoding for several memory types requires neural changes and the activity of distinct regions across the brain. These areas receive broad projections originating in nuclei located in the brainstem which are capable of modulating the activity of a particular area. The histaminergic system is one of the major modulatory systems, and it regulates basic homeostatic and higher functions including a...

Histidine decarboxylase (HDC) catalyzes the biosynthesis of histamine from L-histidine and is expressed throughout the mammalian nervous system by histaminergic neurons. Histaminergic neurons arise in the posterior mesencephalon during the early embryonic period and gradually develop into two histaminergic substreams around the lateral area of the posterior hypothalamus and the more anterior pe...

BACKGROUND The brain histaminergic system plays a critical role in maintenance of arousal. Previous studies suggest that histaminergic neurotransmission might be a potential mediator of general anesthetic actions. However, it is not clear whether histaminergic tuberomamillary nucleus (TMN) is necessarily involved in the sedative/hypnotic effects of general anesthetics. METHODS Male Long Evans...

Clonidine is reported to inhibit the az-adrenoceptor mediated pinnal reflex in mice (3). Clonidine produces its effect by acting as an oc2-adrenergic autoreceptor agonist (1). As such, clonidine is also agonist for presynaptic histamine Hz-receptors (8). To test whether the clonidine-induced inhibition of the pinnal reflex is mediated through adrenergic and/or histaminergic system, the interact...

The activity of histaminergic neurons in the tuberomammillary nucleus (TMN) of the hypothalamus correlates with an animal's behavioral state and maintains arousal. We examined how GABAergic inputs onto histaminergic neurons regulate this behavior. A prominent hypothesis, the "flip-flop" model, predicts that increased and sustained GABAergic drive onto these cells promotes sleep. Similarly, beca...

The histaminergic system is thought to regulate brain reward, but the exact mechanisms are poorly understood. This study aims to reveal the pathophysiological differences in the brain histaminergic system between selectively outbred alcohol-preferring AA and alcohol-avoiding ANA rats by using a combination of biochemical, immunohistochemical, and molecular biological methods. We also want to te...

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...

Background The integrity of the brain histaminergic system is necessary for the unfolding of homeostatic and cognitive processes through the recruitment of alternative circuits with distinct temporal patterns. We recently demonstrated that the fat-sensing lipid mediator oleoylethanolamide indirectly activates histaminergic neurons to exerts its hypophagic effects. The present experiments invest...

Background: The mechanisms of emergence from general anesthesia remain to be elucidated. Recent studies indicate that the central histaminergic system plays a critical role in maintaining wakefulness. In addition, neural pathways regulate wake-sleep cycle are involved anesthesia. this study, we determined propofol using microinjections and single-unit recordings rats.