Cannabinoid Regulation of Nitric Oxide Synthase I (nNOS) in Neuronal Cells

In our previous studies, CB1 cannabinoid receptor agonists stimulated production of cyclic GMP and translocation of nitric oxide (NO)-sensitive guanylyl cyclase in neuronal cells (Jones et al., Neuropharmacology 54:23–30, 2008). The purpose of these studies was to elucidate the signal transduction of cannabinoid-mediated neuronal nitric oxide synthase (nNOS) activation in neuronal cells. Cannabinoid agonists CP55940 (2-[(1S,2R,5S)-5-hydroxy-2-(3-hydroxypropyl) cyclohexyl]-5-(2-methyloctan-2-yl)phenol), WIN55212-2 (R(+)-[2,3-dihydro-5-methyl-3-[(morpholinyl)methyl]pyrrolo[1,2,3-de]-1,4-benzoxazinyl]-(1-naphthalenyl)methanone mesylate), and the metabolically stable analog of anandamide, (R)-(+)-methanandamide stimulated NO production in N18TG2 cells over a 20-min period. Rimonabant (N-(piperidin-lyl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-H-pyrazole-3-carboxamide), a CB1 receptor antagonist, partially or completely curtailed cannabinoid-mediated NO production. Inhibition of NOS activity (NG-nitro-l-arginine) or signaling via Gi/o protein (pertussis toxin) significantly limited NO production by cannabinoid agonists. Ca2+ mobilization was not detected in N18TG2 cells after cannabinoid treatment using Fluo-4 AM fluorescence. Cannabinoid-mediated NO production was attributed to nNOS activation since endothelial NOS and inducible NOS protein and mRNA were not detected in N18TG2 cells. Bands of 160 and 155 kDa were detected on Western blot analysis of cytosolic and membrane fractions of N18TG2 cells, using a nNOS antibody. Chronic treatment of N18TG2 cells with cannabinoid agonists downregulated nNOS protein and mRNA as detected using Western blot analysis and real-time polymerase chain reaction, respectively. Cannabinoid agonists stimulated NO production via signaling through CB1 receptors, leading to activation of Gi/o protein and enhanced nNOS activity. The findings of these studies provide information related to cannabinoid-mediated NO signal transduction in neuronal cells, which has important implications in the ongoing elucidation of the endocannabinoid system in the nervous system

The effects of CRF antagonists, antalarmin, CP154,526, LWH234, and R121919, in the forced swim test and on swim-induced increases in adrenocorticotropin in rats

Exposure to extreme stress has been suggested to produce long-term, detrimental alterations in the hypothalamic–pituitary–adrenal (HPA) axis leading to the development of mental disorders such as depression. Therefore, compounds that block the effects of stress hormones were investigated as potential therapeutics for depression.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46365/1/213_2005_Article_2164.pd

Effect of posterior pituitary denervation (PPD) on prolactin (PRL) and α-melanocyte-stimulating hormone (α-MSH) secretion of lactating rats

Previous data have clearly suggested that the posteriorpituitary (PP), consisting of neural lobe (NL) and intermediatelobe (IL), has a role in the control of anterior pituitaryPRL secretion. However, basic aspects of this regulatory mechanismlike (1), the role of an intact hypothalamic innervation ofthe PP as well as (2) the site of production of previously foundPRL releasing substance(s) have not yet been characterized.Denervation of the PP (PPD) is an effective method for having aselective lesion of the innervation of PP, indeed, PPD results ina disappearance of neurosecretory materials from NL and tyrosinehydroxylase (TH) immunoreactivity from IL, leaving bloodsupply of all three lobes intact. Blood samples were taken fromfreely moving sham and PP-denervated lactating rats before andafter 4-h separation from their pups and during the sucklingstimulus. PPD blocks separation-induced depletion but only attenuatessuckling induced release of PRL. Furthermore, it doublesplasma level of a-MSH during the entire sampling period,which has been used as a marker for in vivo secretory activityof IL cells. Lack of the separation-induced depression in plasmaPRL of PPD animals can be partially restored by normalizing thediabetes insipidus with treatment of a vasopressin analogue, 1-desamino-8-D-arginine-vasopressin (dDAVP). In contrast, d-DAVP, neither alone nor in combination with oxytocin (OXY), canchange PPD-induced elevation of plasma a-MSH as well as attenuationof PRL response induced by suckling. It is concludedthat: (1) contribution of the THDA system parallel to the confirmedrole in the regulation of a-MSH seems to be crucial forthe depletion of plasma PRL induced by separation but not forthe elevation due to suckling stimulus, (2) intact hypothalamicinnervations of both NL and IL, regulating water intake and thesecretion of a-MSH, respectively, are necessary for normal secretoryresponses of AL during lactation, (3) as well as for thepresence of PRF activity in PP, (4) which does not solely responsiblefor suckling-induced PRL release. Therefore, an interplaybetween several substances produced by NIL of the pituitarygland must have been responsible for the intactregulation of PRL secretion during lactation