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Neuronal histamine is crucially involved in a number of physiological functions as well as in neuropsychiatric diseases. Determination of histamine in biological samples is thus of importance in the clinical studies. The aim of this review is to summarize the progress or effort made in this field, with focus on the high-performance liquid chromatography.

The brain-gut peptide ghrelin, a endogenous ligand for the growth hormone secretagogue hormone receptor, is mainly produced by gastric cells in the periphery, regulating energy metabolism via stimulating the appetite. Inside the brain, ghrelin is mainly expressed in the pituitary and in the hypothalamic arcuate nucleus, regulating the synthesis and secretion of neuropeptides that are correlated with feeding behavior, reproduction, and stress responses. Recently, more and more researches focused on the regulating roles of ghrelin on learning and memory, and mood regulation have indicated that ghrelin may inhibit neuronal apoptosis, improve cognitive function, and regulate the activities of neuroendocrine systems such as the hypothalamo-pituitary-adrenal axis and the hypothalamo-pituitary-gonadal axis thus get involved in the pathogenesis of neuropsychiatric diseases. The aim of this review is to summarize the main findings in this field, with the purpose of promoting further studies on the role of ghrelin in the brain.

Objective: To investigate the effect of maternal deprivation on the activity of hypothalamo-pituitary-adrenal (HPA) axis, acute stress response and the sex hormone receptors expression in hypothalamic paraventricular nucleus (PVN) in female rats., Methods: Maternal deprivation model was induced in female Sprague-Dawley (SD) rats. Foot shock was given at different stages of estrus cycle during the adulthood. Plasma estradiol, testosterone and adrenocorticotropin (ACTH) levels were determined by radioimmunoassay; and plasma corticosterone level was measured by enzyme linked immunosorbent assay. The expression of androgen receptor (AR) and estrogen receptor (ER-β) in the hypothalamic PVN was detected by immunohistochemistry., Results: Decreased plasma ACTH and corticosterone levels were found in the proestrus of female rats with maternal deprivation (P=0.012 and P=0.019, respectively). A significant down-regulation (P=0.008) of PVN-AR, but not PVN-ER-β expression was found in female rats with maternal deprivation., Conclusion: Maternal deprivation may reduce the HPA axis activity in female SD rats, which is closely correlated with the fluctuation of the circulating sex hormones. The androgen in the hypothalamus seems to play a more important role than the estrogen in this procedure.

Objective: To evaluate the changes of plasma levels of the excitatory amino acid neurotransmitter aspartic acid (Asp), inhibitory neurotransmitter glycine (Gly) and asparagine (Asn) in patients with major depressive disorder (MDD)., Methods: Plasma samples were collected from 15 MDD patients (9 males and 6 females, aged 32-64 y) and 14 healthy subjects (7 males and 7 females, aged 30-65 y); and also collected from 7 MDD patients (5 males and 2 females) 2 months after antidepressant treatment. The plasma levels of amino acids were determined by high performance liquid chromatography with fluorescence detection method., Results: Plasma Asp and Gly levels were significantly lower in MDD patients than those in controls (P<0.04). There were positive correlations between plasma levels of Gly and Asp, and between Gly and Asn (P<0.005) in the control group; while in MDD patients, a significant positive correlation was found only between plasma levels of Gly and of Asp (P<0.001). MDD patients did not show significant changes in plasma Asp, Asn and Gly levels after antidepressant treatment compared to those before treatment., Conclusion: The reduced plasma Asp and Gly levels may serve as a clinical biomarker for MDD.