Serotonin content is elevated in the immune cells of histidine decarboxylase gene knock-out (HDCKO) mice. Focus on mast cells

Abstract

It seems likely that serotonin replaces the deficient histamine in the heparin-biogenic amine complex in the mast cell granules.

Histidine decarboxylase (HDC) knock out mouse immune cells have altered expression of ACTH, triiodothyronine and endorphin

“…In the light of these observations, the infl uence of histamine defi ciency in our experiments on the non-biogenic hormone levels is not surprising. However, serotonin level in the previous experiment [17] was significantly elevated in each cell types, while -in the present experiments-ACTH and endorphin levels were reduced and only T 3 level in mo-gran was elevated signifi cantly. This could mean that histamine gene defi ciency rather infl uences the serotonin concentration of the immune cells, than that of the other hormones, which could be explained by the compensation of one of the biogenic amines by the other one.…”

“…1d). The absence of granulation in mast cells corresponds to the earlier observations [17,18]. T 3 fl uorescence is paler in the wild animals (Fig.…”

“…The results show that these hormones -ACTH, endorphin and T 3 -are present also in the immune cells of mice. In earlier experiments [17] immune cells of the histamine-defi cient HDC-KO mice contained signifi cantly more serotonin, than those of the wild type animals. The reason for doing these present experiments was to clarify whether one biogenic amine (serotonin) compensated the absence of the other (histamine), or in the absence of HDC and consequently histamine, an endocrine imbalance takes place in the cells, causing differences in the amount (and localization) of other hormones.…”

“…In previous experiments [17] the serotonin content of histidine decarboxylase gene knock-out (HDC-KO) mice was elevated in the immune cells. It was supposed that serotonin compensates for the missing functions of the other biogenic amine, histamine in mast cell granules as well as in othernormally histamine containing-immune cells.…”

Serotonin and histamine storage in mast cell secretory granules is dependent on serglycin proteoglycan

“…We also noted that the onset of serotonin storage occurred considerably later during the BMMC differentiation process than storage of histamine, thus suggesting that serotonin storage is a characteristic of more mature MCs whereas histamine storage is initiated earlier during MC differentiation. Also of interest is a recent report showing that serotonin storage is increased in MCs lacking HDC expression, 29 introducing the possibility that histamine and serotonin may compete for ''space'' in the granules, perhaps by competing for binding to the glycosaminoglycans attached to the serglycin protein core. Previous studies have suggested the existence of TPH in MCs, 8,30,31 but before this study, it was not known whether MCs preferentially express the TPH-1 or TPH-2 isoform.…”