Using extracellular single-unit recordings alone and in combination with neurobiotin juxtacellular labeling and histamine immunohistochemistry, we have identified, for the first time in nonanesthetized, head-restrained mice, histamine neurons in the tuberomammillary nuclei of the posterior hypothalamus. They are all characterized by triphasic broad action potentials. They are active only during...

The phylogenetic relationships within the Arthropoda have remained controversial for more than a century. Comparative studies on structure and development of the nervous system have contributed important arguments to this discussion. Earlier studies revealed only few similarities between the brain morphology in representatives of the Chelicerata and the Mandibulata. In the present report, we an...

Previous studies have demonstrated that central injection of L-carnosine (beta-alynyl-L-histidine), dipeptide synthesized in mammalian muscles, affects renal sympathetic nerve activity (RSNA) and blood pressure (BP) in anesthetized rats. In the present study, using urethane-anesthetized rats, we examined the dose-dependent effects of intravenous (IV) injection of various doses of anserine, dipe...

Histaminergic neurons of the tuberomammillary nucleus (TM) project monosynaptically to the supraoptic nucleus (SON). This projection remains intact in our hypothalamic slices and permits investigation of both brief synaptic responses and the effects of repetitively activating this pathway. SON oxytocin (OX) neurons respond to single TM stimuli with fast IPSPs, whose kinetics resemble those of G...

We have explored the role of endogenous dopamine in the control of histaminergic neuron activity in mouse brain regions evaluated by changes in tele-methylhistamine (t-MeHA) levels. In vitro, methamphetamine released [(3)H]noradrenaline but failed to release [(3)H]histamine from synaptosomes. In vivo, methamphetamine enhanced t-MeHA levels by about 2-fold with ED(50) values of approximately 1 m...

Reliable estimates of the quantum size in histaminergic neurons are not available. We have exploited two unusual opportunities in the fly's (Drosophila melanogaster) visual system to make such determinations for histaminergic photoreceptor synapses: 1) the possibility to microdissect successively from whole fly heads freeze-dried in acetone: the compound eyes; the first optic neuropils, or lami...

Recent discoveries demonstrated that recruitment of alternative brain circuits permits compensation of memory impairments following damage to brain regions specialized in integrating and/or storing specific memories, including both dorsal hippocampus and basolateral amygdala (BLA). Here, we first report that the integrity of the brain histaminergic system is necessary for long-term, but not for...

H1 and H2 histamine receptor antagonists, although developed many decades ago, are still effective for the treatment of allergic and gastric acid-related conditions. This article focuses on novel aspects of the pharmacology and molecular mechanisms of histamine receptors that should be contemplated for optimizing current therapies, repositioning histaminergic ligands for new therapeutic uses, o...