Na Channel Is a Physiological [Na] Detector in Oxytocin- and Vasopressin-Releasing Magnocellular Neurosecretory Cells of the Rat Supraoptic Nucleus.

The gene encodes Na, an atypical noninactivating Na channel, whose expression in sensory circumventricular organs is essential to maintain homeostatic responses for body fluid balance. However, Na has also been detected in homeostatic effector neurons, such as vasopressin (VP)-releasing magnocellular neurosecretory cells (MNC) that secrete VP (antidiuretic hormone) into the bloodstream in response to hypertonicity and hypernatremia. Yet, the physiological relevance of Na expression in these effector cells remains unclear.

Histamine H and H receptor activation increases the expression of Glucose Transporter 1 (GLUT-1) in rat cerebro-cortical astrocytes in primary culture.

Astrocytes take up glucose via the 45 kDa isoform of the Glucose Transporter 1 (GLUT-1), and in this work we have investigated whether histamine regulates GLUT-1 expression in rat cerebro-cortical astrocytes in primary culture. Cultured astrocytes expressed histamine H and H receptors (HRs and HRs) as evaluated by radioligand binding. Receptor functionality was confirmed by the increase in the intracellular concentration of Ca (HR) and the inhibition of forskolin-induced cAMP accumulation (HR).

Adenosine A and histamine H receptors interact at the cAMP/PKA pathway to modulate depolarization-evoked [H]-GABA release from rat striato-pallidal terminals.

We previously reported that the activation of histamine H receptors (HRs) selectively counteracts the facilitatory action of adenosine A receptors (ARs) on GABA release from rat globus pallidus (GP) isolated nerve terminals (synaptosomes). In this work, we examined the mechanisms likely to underlie this functional interaction. Three possibilities were explored: (a) changes in receptor affinity for agonists induced by physical AR/HR interaction, (b) opposite actions of ARs and HRs on depolarization-induced Ca entry, and (c) an AR/HR interaction at the level of adenosine 3',5'-cyclic monophosphate (cAMP) formation.

Histamine H receptor activation stimulates calcium mobilization in a subpopulation of rat striatal neurons in primary culture, but not in synaptosomes.

The histamine H receptor (HR) is abundantly expressed in the Central Nervous System where it regulates several functions pre and postsynaptically. HRs couple to Gα proteins and trigger or modulate several intracellular signaling pathways, including the cAMP/PKA pathway and the opening of N- and P/Q-type voltage-gated Ca channels. In transfected cells, activation of the human HR of 445 amino acids (hHR) results in phospholipase C (PLC) stimulation and release of Ca from intracellular stores.

Heterologous, PKC-Mediated Desensitization of Human Histamine H3 Receptors Expressed in CHO-K1 Cells.

Desensitization is a major mechanism to regulate the functional response of G protein-coupled receptors. In this work we studied whether the human histamine H3 receptor of 445 amino acids (hH3R445) experiences heterologous desensitization mediated by PKC activation. Bioinformatic analysis indicated the presence of Serine and Threonine residues susceptible of PKC-mediated phosphorylation on the third intracellular loop and the carboxyl terminus of the hH3R445.