LPA signaling is required for dopaminergic neuron development and is reduced through low expression of the LPA1 receptor in a 6-OHDA lesion model of Parkinson's disease.

Lysophosphatidic acid (LPA) is a bioactive phospholipid that activates at least five known G-protein-coupled receptors (GPCRs): LPA1-LPA5. The nervous system is a major locus for LPA1 expression. LPA has been shown to regulate neuronal proliferation, migration, and differentiation during central nervous system development as well as neuronal survival. Furthermore, deficient LPA signaling has been implicated in several neurological disorders including neuropathic pain and schizophrenia. Parkinson's disease (PD) is a neurodegenerative movement disorder that results from the loss of dopaminergic (DA) neurons in the substantia nigra pars compacta (SNc). The specific molecular pathways that lead to DA neuron degeneration, however, are poorly understood. The influence of LPA in the differentiation of mesenchymal stem cells (MSCs) into DA neurons in vitro and LPA1 expression in a 6-hydroxydopamine (6-OHDA) lesion model of PD in vivo were examined in the present study. LPA induced neuronal differentiation in 80.2 % of the MSC population. These MSCs developed characteristic neuronal morphology and expressed the neuronal marker, neuron-specific enolase (NSE), while expression of the glial marker, glial fibrillary acidic protein (GFAP), was absent. Moreover, 27.6 % of differentiated MSCs were positive for tyrosine hydroxylase (TH), a marker for DA neurons. In the 6-OHDA PD rat model, LPA1 expression in the substantia nigra was significantly reduced compared to control. These results suggest LPA signaling via activation of LPA1 may be necessary for DA neuron development and survival. Furthermore, reduced LPA/LPA1 signaling may be involved in DA neuron degeneration thus contributing to the pathogenesis of PD.

Catalpol regulates function of hypothalamic-pituitary-adrenocortical-axis in an Alzheimer's disease rat model.

AIMS: To investigate the regulating effects of catalpol on the hypothalamic-pituitary- adrenocortical-axis (HPA) in an Alzheimer's disease (AD) rat model. METHODS: Healthy male Wistar Rats were selected. The AD model was generated by orthotopic injection of beta-amyloid 25-35 (Abeta25-35) into the right lateral ventricle. The animals were divided into five study groups: Catalpol at low dose (5 mg/kg), Catalpol at high dose (10 mg/kg), model control group and sham surgery control group, n = 9 respectively. The serum concentration of hydrocortisone (HYD), adrenocorticotropin (ACTH) and corticotropin releasing hormone (CRH) determined by Enzyme-Linked Immunosorbent Assay (ELISA). Structural alterations of the hypothalamus were examined by H&E stain and electron microscope. The CRH receptor 1 (CRHR1) positive neurons were detected with immunohistochemistry. RESULTS: Serum HYD level was significantly increased (p < 0.01), and both ACTH and CRH were dramatically decreased (p < 0.01) in the AD model group rats compared with normal control rats at day 7. Catalpol treatment was able to improve the hormone secretion disorder in AD model group rats compared with the model group (p < 0.01 or p < 0.05) in particular at 21 days. Structure damage of hypothalamus in the AD rat as evidenced less CRHR1 positive neurons, rough endoplasmic reticulum dilation and degranulation, and mitochondrial swelling under electron microscope. Catalpol treatment at both high and low doses was able to alleviate the structure damage of the hypothalamus in the AD rats. CONCLUSIONS: Catalpol could improve the endocrine function of the HPA and alleviate the structural damage of hypothalamus in AD rats.

Involvement of CGRP and CGRPl receptor in nociception in the basolateral nucleus of amygdala of rats.

The present study was performed to investigate the role of calcitonin gene-related peptide (CGRP) and its receptor in nociception in the basolateral nucleus of amygdala (BLA) of rats. Hindpaw withdrawal latencies (HWLs) to noxious thermal and mechanical stimulations were measured by hot plate and Randall Selitto tests. The HWL to both thermal and mechanical stimulations increased significantly after intra-BLA administration of 1.0 or 2.0 nmol CGRP, but not 0.5 nmol, indicating that CGRP plays an anti-nociceptive role in BLA of rats. The anti-nociceptive effect of 1.0 nmol CGRP was blocked significantly by administration of 1.0 or 2.0 nmol CGRP8-37, a selective antagonist of CGRP1 receptor, which suggests that the anti-nociceptive effect of CGRP is mediated by the CGRP1 receptor. Taken together, the results indicate that both CGRP and CGRP1 receptor play important roles in nociceptive modulation in the BLA of rats.