Regulation of histamine synthesis: Altered synthesis and level of histamine in the hypothalamus of rats by repeated administration of histamine H1 and H2 receptor antagonists

Abstract

Repeated administration of histamine H1 and H2 receptor antagonists resulted in significant alterations in the hypothalamic histamine level of rats and similar changes in the HD activity of the hypothalami were observed after these treatment. The changes in the level run parallel with the modifications in the HD activity. The effects of classical antihistaminergic agents were however opposite to that of the specific H2 antagonists, namely chloropyramine and tripelennamine markedly enhanced while metiamide and cimetidine diminished the hypothalamic level of histamine.

Regulatory influence of histamine receptor activation and inhibition on the synthesis and level of hypothalamic histamine

“…In both this and previous experiments [2], histamine H 1 antagonists chloropyramine and tripelennamine produced an increased synthesis and level of HA in the hypothalamus (Table 1). In this series the H 2 antagonists metiamide and cimetidine caused similar effects; whereas the highly specific H~ agonist 2-pyridylethylamine (PEA) produced diminutions in both the synthesis and level of this amine (Table 3).…”

“…administration of 10 rng/kg of chloropyramine and 20 mg/kg of tripelennamine resulted in similar but somewhat higher enhancement in the hypothalamic histamine level [2]. in contrast, 30 rng/kg of metiamide and 10 mg/kg of cimetidine, given in a detergent-containing suspension to rats i.p., twice daily for 3 days, produced small but significant decreases in the hypothalamic histamine content.…”

“…In previous papers we described the influence of histamine H 2-and H:receptor antagonists on HD activity in the stomach [11 and the hypothalamus [2]. These experiments showed significant stimulation on the synthesis rate and the level of histamine by the administration of HA-receptor antagonists.…”

“…Preliminary studies showed that a similar mechanism, via histamine Hi-receptor, might play a regulatory role in the synthesis and level of this amine in the central nervous system [2]. A detailed analysis of the metabolic effects of various histamine H 1-and H2-receptor agonists and antagonists was carried out.…”

Regulation of histidine decarboxylase activity in rat hypothalamusin vitro by ATP and cyclic AMP: Enzyme inactivation under phosphorylating conditions

“…Our previous studies showed the regulatory influence of histamine receptor agonists and antagonists on the synthesis and level of hypothalamic histamine and suggested the possible involvement of cyclic nucleotides in this action [1][2]. Previous and recent evidence that HA and its agonists stimulate the production of cAMP in different brain regions, including hypothalamus [3][4][5], have further strengthened the reality of this conception.…”