Dynamic Changes of Endogenic or Exogenic β-Carboline Alkaloid Harmine in Different Mammals and Human in vivo at Developmental and Physiological States

ObjectiveSeveral β-carboline alkaloids (βCBs), such as harmine, harmaline, harmane, and nor-harmane, are effective for Alzheimer’s disease mouse models. They can be found in some plants, common foodstuffs, and blank plasma of various mammals. However, whether these compounds in mammals are exogenous or endogenous remain unclear.MethodsThe exposure levels of βCBs and of neurotransmitters in plasma and tissues of pup rats, aging rats, mice of different physiological states, and healthy volunteers were detected by using UPLC-MS/MS. Plasma and tissue samples from 110 newborn rats up to 29 days old at 11 sampling points were collected and were analyzed to determine the concentration variation of βCBs in the developmental phase of newborn rats. The plasma of rats aged 2 to 18 months was used to detect the variation trend of βCBs and with some neurotransmitters. The plasma samples of normal C57BL/6 mice, APP/PS1 double transgenic mice, and scopolamine-induced memory impairment mice were collected and were analyzed to compare the difference of βCBs in different physiological states. The exposure levels of βCBs such as harmine, harmaline, and harmane in plasma of 550 healthy volunteers were also detected and analyzed on the basis of gender, race, and age.ResultsResults showed that harmine was the main compound found in rats, mice, and human, which can be detected in a newborn rat plasma (0.16 ± 0.03 ng/ml) and brain (0.33 ± 0.14 ng/g) without any exogenous consumption. The concentration of harmine in rat plasma showed a decreasing trend similar to the exposure levels of neurotransmitters such as 5-hydroxytryptamine, acetylcholine chloride, glutamic acid, tyrosine, and phenylalanine during the growth period of 18 months. The harmine exposure in rats and human indicates high dependence on the physiological and pathological status such as aging, gender, and race.ConclusionThe dynamic changes of harmine exposure in different animals and human, in vivo, at developmental and physiological states indicate that harmine is a naturally and widely distributed endogenous substance in different mammals and human. In addition to exogenous ingestion, spontaneous synthesis might be another important source of harmine in mammals, which should be verified by further experiment.

Hyperoxia-Exposed Lung Injury Upregulates DVL-1 Protein Expression And Activates Wnt/β-Catenin Signaling Pathway in Newborn Rat Lung

Background: Bronchopulmonary dysplasia (BPD) is a serious and lifelong pulmonary disease in premature neonates, which has an influence on a quarter of premature newborns. Wingless/integrated(Wnt)/β-catenin signaling pathway affects lung cell differentiation and lung tissue structure, and is abnormal activation in the lungs of rats with pulmonary fibrosis. Method: Newborn rats were subjected to hyperoxia-exposure, histopathological changes in lung tissues were evaluated through Immunohistochemistry (IHC), Dishevelled (DVL-1) and signaling pathways were detected through western blotting and real-time PCR. Results: Contrasting with the normoxic lungs, hyperoxia-exposed lungs demonstrated larger alveoli, less alveoli and thicker alveolar septa, and the number of alveoli reduced obviously, alveoli enlarged seriously in hyperoxia group. SOD activity was decreased (7 th day: P < 0.05; 14 th day: P < 0.01), and MDA was increased (7 th day: P < 0.05; 14 th day: P < 0.01) after hyperoxia exposure. Protein and mRNA expression levels of β-catenin, DVL-1, Ctnnbl1 and Cyclin D1 were upregulated by hyperoxia exposure on 7 th day( P < 0.01) and 14 th day( P < 0.01). Conclusion: We confirmed the positive role of DVL-1 and Wnt/β-catenin signaling pathway in promoting BPD under hyperoxia conditions, and provided promising therapeutic targets in the future.

Significant β-carboline Alkaloid Harmine in Different Developmental States of Mammals in Vivo: Endogenic or Exogenic?

Background: Several β-carboline alkaloids (βCBs), harmine, harmaline, harmane, and nor-harmane, are effective for Alzheimer’s disease (AD) model mice. They were discovered in some plants, common foodstuffs, and in blank plasma of various mammals. However, whether these compounds in mammals are exogenous or endogenous remained unclear. The exposure levels of these βCBs in plasma and tissues of pup rats, aging rats and volunteer were detected by UPLC-MS/MS.Result: Results showed that harmine was the main compound found in rats, mice, human, and even in newborn rats without consumption. The changes of harmine concentration showed a high dependence with growth (aging), gender and race. And the concentration of harmine in rat plasma showed a decreasing trend during the growth period of 18 months. Conclusion: These results revealed that harmine may be relevant to AD. The exposure level of harmine in plasma indicate that in addition to exogenous ingestion, spontaneous synthesis might be another important source of harmine in mammals.

GABAB Receptor-Mediated Impairment of Intermediate Progenitor Maturation During Postnatal Hippocampal Neurogenesis of Newborn Rats

The neurotransmitter GABA and its receptors assume essential functions during fetal and postnatal brain development. The last trimester of a human pregnancy and early postnatal life involves a vulnerable period of brain development. In the second half of gestation, there is a developmental shift from depolarizing to hyperpolarizing in the GABAergic system, which might be disturbed by preterm birth. Alterations of the postnatal GABA shift are associated with several neurodevelopmental disorders. In this in vivo study, we investigated neurogenesis in the dentate gyrus (DG) in response to daily administration of pharmacological GABAA (DMCM) and GABAB (CGP 35348) receptor inhibitors to newborn rats. Six-day-old Wistar rats (P6) were daily injected (i.p.) to postnatal day 11 (P11) with DMCM, CGP 35348, or vehicle to determine the effects of both antagonists on postnatal neurogenesis. Due to GABAB receptor blockade by CGP 35348, immunohistochemistry revealed a decrease in the number of NeuroD1 positive intermediate progenitor cells and a reduction of proliferative Nestin-positive neuronal stem cells at the DG. The impairment of hippocampal neurogenesis at this stage of differentiation is in line with a significantly decreased RNA expression of the transcription factors Pax6, Ascl1, and NeuroD1. Interestingly, the number of NeuN-positive postmitotic neurons was not affected by GABAB receptor blockade, although strictly associated transcription factors for postmitotic neurons, Tbr1, Prox1, and NeuroD2, displayed reduced expression levels, suggesting impairment by GABAB receptor antagonization at this stage of neurogenesis. Antagonization of GABAB receptors decreased the expression of neurotrophins (BDNF, NT-3, and NGF). In contrast to the GABAB receptor blockade, the GABAA receptor antagonization revealed no significant changes in cell counts, but an increased transcriptional expression of Tbr1 and Tbr2. We conclude that GABAergic signaling via the metabotropic GABAB receptor is crucial for hippocampal neurogenesis at the time of rapid brain growth and of the postnatal GABA shift. Differentiation and proliferation of intermediate progenitor cells are dependent on GABA. These insights become more pertinent in preterm infants whose developing brains are prematurely exposed to spostnatal stress and predisposed to poor neurodevelopmental disorders, possibly as sequelae of early disruption in GABAergic signaling.