Repeated Administration of Dexamethasone Increases Phosphoinositide‐Specific Phospholipase C Activity and mRNA and Protein Expression of the Phospholipase C β<sub>1</sub> Isozyme in Rat Brain

Dwivedi, Yogesh K.; Pandey, Ghanshyam N.

doi:10.1046/j.1471-4159.1999.0730780.x

Cited by 19 publications

(8 citation statements)

References 66 publications

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“…Indeed, up to date, only corticoids were reported to regulate the expression of PLC enzymes (Dwivedi & Pandey 1999, Cueille et al 2003. Furthermore, although oestradiol was suggested to facilitate norepinephrine-, CCh-and OTinduced PLC activation at a post-receptor level in the myometrium (Riemer et al 1987, Phaneuf et al 1995, Abdalla et al 2000, no studies have addressed its direct effect on PLC expression.…”

Section: Discussionmentioning

confidence: 99%

Up-regulation of rat myometrial phospholipases Cβ1 and Cβ3 correlates with increased term sensitivity to carbachol and oxytocin

Houdeau

Levy²,

Mhaouty-Kodja³

2005

Journal of Endocrinology

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In the present study, we compared rat uterine contractility and myometrial inositol phosphate (InsP) production in response to activation of muscarinic and oxytocin receptors during pregnancy and at term. The level of myometrial phospholipase (PL) C was also determined by Western blotting at different stages of pregnancy and following administration of oestradiol, progesterone or vehicle. The results showed an increased potency of carbachol (CCh), a cholinergic muscarinic agonist, and oxytocin (OT) to enhance myometrial InsP production at term. This correlated with an increased potency of both agonists to induce contraction of the circular but not the longitudinal muscle. For both InsP production and contractile activity, the maximal response of CCh was unaltered, while that of OT was significantly increased. Interestingly, the increased responsiveness to CCh and OT was associated with an up-regulation of PLC 1 and PLC 3 enzymes. Such regulation is under the control of oestradiol since administration of this steroid to pregnant rats increased the amount of both enzymes by 200-260%. In contrast, progesterone administration was without effect. The present study presents the first evidence that the expression of rat myometrial PLC 1 and PLC 3 is under the positive control of oestradiol. This could participate in the enhancement of myometrial InsP accumulation and uterine contraction at term in response to CCh and OT. Based on contraction studies, we also propose that the longitudinal and circular uterine muscles differ in the regulation of the PLC pathway during pregnancy.

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Section: Discussionmentioning

confidence: 99%

Up-regulation of rat myometrial phospholipases Cβ1 and Cβ3 correlates with increased term sensitivity to carbachol and oxytocin

Houdeau

Levy²,

Mhaouty-Kodja³

2005

Journal of Endocrinology

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“…The procedures for RNA isolation and competitive RT‐PCR analysis have been described previously (Dwivedi and Pandey 1999). Brain tissues were homogenized in 4 m guanidine isothiocyanate, 50 m m Tris–HCl (pH = 7.4), and 25 m m EDTA, and the total RNA was isolated by CsCl 2 ultracentrifugation.…”

Section: Methodsmentioning

confidence: 99%

Reduced activation and expression of ERK1/2 MAP kinase in the post‐mortem brain of depressed suicide subjects

Dwivedi

Rizavi

Roberts³

et al. 2001

Journal of Neurochemistry

306

197

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The extracellular regulated kinases (ERK) 1 and ERK2 are members of mitogen-activated protein (MAP) kinase family that play an important role in transducing extracellular signals to the nucleus and have been implicated in a broad spectrum of biological responses. To test the hypothesis that MAP kinases may be involved in depression, we examined the activation of p44/42 MAP kinase and expression of ERK1 and ERK2 in the post-mortem brain tissue obtained from non-psychiatric control subjects (n 11) and age-and the post-mortem interval-matched depressed suicide subjects (n 11). We observed that p44/42 MAP kinase activity was signi®cantly decreased in the prefrontal cortical areas (Brodmann's areas 8, 9 and 10) and the hippocampus of depressed suicide subjects without any change in the cerebellum. This decrease was associated with a decrease in mRNA and protein levels of ERK1 and ERK2. In addition, the expression of MAP kinase phosphatase (MKP)2, a`dual function' ERK1/2 phosphatase, was increased in the prefrontal cortex and hippocampus. These studies suggest that p44/42 MAP kinases are less activated in the post-mortem brain of depressed suicide subjects and this may be because of reduced expression of ERK1/2 and increased expression of MKP2. Given the role of MAP kinases in various physiological functions and gene expression, alterations in p44/42 MAP kinase activation and expression of ERK1/2 may contribute signi®cantly to the pathophysiology of depressive disorders.

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“…PI-PLC activity was measured in both membrane and cytosol fractions by the procedures described earlier by us (Dwivedi and Pandey 1999b) using 5 g protein/ tube in an incubation buffer (20 mM Tris-HCl, 1 mM CaCl 2 , and 100 mM KCl, pH 7.4) containing 10 mM lithium chloride, PIP 2 substrate (50 M unlabeled PIP 2 , 2.0 Ci/ml [ 3 H] PIP 2 , and 0.5 mg/ml certimide) in a total volume of 100 l at 37 Њ C for 10 min. The reaction was terminated by the addition of 500 l of 1 M HCl and 500 l of a mixture of chloroform/methanol (l:l vol/vol).…”

Section: Determination Of Pi-plc Activity In Membrane and Cytosol Framentioning

confidence: 99%

Protein Kinase C and Phospholipase C Activity and Expression of Their Specific Isozymes Is Decreased and Expression of MARCKS Is Increased in Platelets of Bipolar but Not in Unipolar Patients

Pandey

Dwivedi

SridharaRao

et al. 2002

Neuropsychopharmacology

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Phospholipase C (PLC) and protein kinase C (PKC) are important components of the phosphoinositide (PI) signaling system. To examine if the abnormalities observed in the PIdrolysis of the substrate, phosphatidyl inositol 4,5-bisphosphate (PIP 2 ), by the enzyme phospholipase C (PLC), resulting in the formation of two second messengers, inositol 1,4,5-trisphophate (IP 3 ) and diacylglycerol (DAG) (Berridge and Irvine 1989). IP 3 stimulates the release of intracellular calcium from the endoplasmic reticulum, and DAG stimulates the enzyme protein kinase C (PKC) (Nishizuka 1992), which is one of the major intracellular mediators of signals generated by the stimulation of cell surface receptors.Several studies indicate abnormalities of the PI signaling system in patients with unipolar or bipolar disorders. It has been reported that the hydrolysis of PIP 2 by several agonists, such as sodium fluoride (NaF) and GTP ␥ S, is altered in the postmortem brain of depressed Pacheco et al. 1996). PI signal transduction determined by serotonin (5HT)-, thrombin-, and NaF-stimulated IP formation has also been reported to be increased in platelets of depressed patients (Mikuni et al. 1991;Karege et al. 1996). These abnormalities may be related to abnormalities in receptors, such as 5HT 2A , 5HT 2C , muscarinic M 1 and M 2 , or ␣ 2 adrenergic receptors linked to the PI signaling system or to abnormal levels of substrates, such as PIP 2 , or to components of the signaling cascade, such as G-proteins, PKC, or PLC. Abnormalities in 5HT 2A (Pandey et al. 1995), ␣ 2 adrenergic receptors (Pandey et al. 1990), G-proteins (Garcia-Sevilla et al. 1997Karege et al. 1998;Gurguis et al. 1999), and levels of PIP 2 , a substrate for PI-PLC (Brown et al. 1993;Soares and Mallinger 1996;Soares et al. 1999), have been reported in platelets of unipolar and/or bipolar patients. PLC and PKC are two crucial components of the PI signaling system. Both PKC and PLC have been shown to be involved in a variety of physiological functions, such as synthesis, release, and reuptake of neurotransmitters, neuronal development, transcription, longterm potentiation (LTP), and behavioral responses (Nishizuka 1992). Although the role of PLC in affective disorders has not been fully investigated, some studies have shown abnormalities of PLC in depression and suicide Pandey et al. 1999). On the other hand, very few studies have examined the role of PKC in bipolar or unipolar disorders, although PKC has been implicated in the pathophysiology of bipolar disorders. For example, it has been reported that PKC activity as well as translocation of PKC from cytosol to membrane are increased in platelets of bipolar patients and that lithium treatment alters the activity of PKC in platelets (Friedman et al. 1993;Wang et al. 1999). Further evidence for the involvement of PKC in bipolar disorders is derived from observations that lithium exerts significant effects on PKC in a number of cell systems, including central nervous system (CNS) (Manji et al. 1993(Manji et al. , 1995Manji ...

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Repeated Administration of Dexamethasone Increases Phosphoinositide‐Specific Phospholipase C Activity and mRNA and Protein Expression of the Phospholipase C β₁ Isozyme in Rat Brain

Cited by 19 publications

References 66 publications

Up-regulation of rat myometrial phospholipases Cβ1 and Cβ3 correlates with increased term sensitivity to carbachol and oxytocin

Up-regulation of rat myometrial phospholipases Cβ1 and Cβ3 correlates with increased term sensitivity to carbachol and oxytocin

Reduced activation and expression of ERK1/2 MAP kinase in the post‐mortem brain of depressed suicide subjects

Protein Kinase C and Phospholipase C Activity and Expression of Their Specific Isozymes Is Decreased and Expression of MARCKS Is Increased in Platelets of Bipolar but Not in Unipolar Patients

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Repeated Administration of Dexamethasone Increases Phosphoinositide‐Specific Phospholipase C Activity and mRNA and Protein Expression of the Phospholipase C β1 Isozyme in Rat Brain

Cited by 19 publications

References 66 publications

Up-regulation of rat myometrial phospholipases Cβ1 and Cβ3 correlates with increased term sensitivity to carbachol and oxytocin

Up-regulation of rat myometrial phospholipases Cβ1 and Cβ3 correlates with increased term sensitivity to carbachol and oxytocin

Reduced activation and expression of ERK1/2 MAP kinase in the post‐mortem brain of depressed suicide subjects

Protein Kinase C and Phospholipase C Activity and Expression of Their Specific Isozymes Is Decreased and Expression of MARCKS Is Increased in Platelets of Bipolar but Not in Unipolar Patients

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Repeated Administration of Dexamethasone Increases Phosphoinositide‐Specific Phospholipase C Activity and mRNA and Protein Expression of the Phospholipase C β₁ Isozyme in Rat Brain