Histamine-induced plasticity and gene expression in corticostriatal pathway under hyperammonemia

Area of Science:

• Neuroscience
• Pharmacology
• Biochemistry

Background:

• Histamine H3 receptor (H3R) antagonists/inverse agonists are known to increase vigilance.
• Hyperammonemia affects brain function and may be linked to altered wakefulness.
• Understanding histaminergic pathways is crucial for developing treatments for neurological disorders.

Purpose of the Study:

• To investigate brain histaminergic pathways under hyperammonemia.
• To analyze the transcriptome of receptors and signaling cascades.
• To provide a rationale for wake-promoting therapies in hyperammonemic disorders.

Main Methods:

• Studied histamine-induced long-lasting depression of corticostriatal synaptic transmission (LLDhist).
• Investigated actions of H3R and dopamine 1 receptor (D1R) agonists/antagonists in a mouse model of hyperammonemia (LGS-KO).
• Analyzed gene transcription in cortex and dorsal striatum, comparing with human hepatic encephalopathy.

Main Results:

• LGS-KO mice showed reduced histamine-induced direct depression (DD) but not LLD.
• D1R activation suppressed LLDhist in LGS-KO mice, but not in wild-type (WT) mice.
• Reduced molecular signature of wakefulness observed in the diseased cortex of LGS-KO mice.

Conclusions:

• Findings support the development of aminergic wake-promoting therapeutics for hyperammonemic disorders.
• The study elucidates the role of histaminergic and dopaminergic systems in hyperammonemia-induced cognitive impairment.
• Identified potential therapeutic targets for improving vigilance in patients with liver disease.