Kinetic and pharmacological properties of [3H]-histamine transport into cultured type 1 astrocytes from neonatal rats

Abstract

Astrocytes participate in the clearance of extracellular histamine by electrodiffusion and active transport by a yet not identified carrier. Taken up histamine can be converted to tele-methylhistamine within astrocytes thus indicating the involvement of astrocytes not only in clearance but also in the inactivation of histamine.

Histamine (re)uptake by astrocytes: an experimental and computational study

“…1 shows that the replacement of sodium chloride in the incubation medium with choline chloride or ouabain treatment significantly, but not completely decrease histamine uptake into cultured neonatal rat astrocytes at 37 °C. This reconfirms our previous finding [13] concerning the involvement of the two different transport pathways, active and passive one by which histamine is carried into astrocytes at 37 °C. The transport of histamine into shake off cells is probably electrodiffusion, as it seems not to be affected neither by lack of sodium ions in the incubation medium nor by ouabain treatment [11].…”

“…Regardless the fact that histamine probably adopts its role as a classical signaling molecule not earlier than by postnatal day 20 [39], it is also taken up into neonatal rat astrocytes with a half time of 1.3 min [13] that is similar to its blood inactivation time of 0.5-3.5 min [40,41]. In addition, astrocytes express mRNA for HNMT, histamine degrading enzyme [13,42], which supports the notion that uptake and subsequent metabolism by glial cells of released histamine from neurons may play important role in regulating extracellular histamine concentration.…”

“…At that point, the cultures contained 93-100 % type 1 astrocytes, determined by immunochemical staining for glial fibrillary acidic protein [37]. Since the time course of histamine uptake has already been reported in our recent paper [13], we proceeded with experiments concerning sodium dependence and ouabain sensitivity. Fig.…”

“…Glial cells were also found to be involved in the continuous removal of neuronal histamine from the synaptic cleft in in vivo conditions [12]. In our previous work, we suggested that histamine is taken up into cultured neonatal rat astrocytes by at least two different transport systems [13]. A high affinity, low capacity, energy-and temperaturedependent transport system and a low affinity, high capacity system which shows little energy and temperature dependence and shares some similarities with uptake 2 .…”