Metformin prevents vascular prostanoid release alterations induced by a high-fat diet in rats.

Perivascular adipose tissue dysfunction induced by high-fat feeding leads to alterations in the modulation of inflammation, contractile activity of the vascular smooth muscle and endothelial function, all risk factors in the development of hypertension. Metformin, an activator of AMP-activated protein kinase (AMPK), is currently the first-line drug treatment for type 2 diabetes (T2DM) and metabolic syndrome. Besides its glucose-lowering effect, there is an interest in actions of this drug with potential relevance in cardiovascular diseases. The high-fat (HF) diet is an experimental model that resembles human metabolic syndrome. We have previously reported an altered pattern of prostanoid release in mesenteric vessels in this model. The aim of this study was to analyse the effects of metformin on mesenteric vascular bed prostanoid release, adiposity index and its relation to blood pressure in Sprague-Dawley rats fed a HF diet for 8 and 12 weeks. Eight groups were used: control (C8, C1), HF diet (HF8, HF12, 50% w/w bovine fat), metformin-treated (CMf8, CMf12, 500 mg/kg/day) and metformin-treated HF diet (HFMf8, HFMf12, both treatments). HF diet increased mesenteric vascular bed adiposity index (%, HF8: 1.7±0.1 vs C8: 0.9±0.04 and HF12: 1.8±0.1 vs C12: 0.8±0.1, P<.001); systolic blood pressure (SBP, mm Hg, HF8: 145±6 vs C8: 118±4, P<.01 and HF12: 151±1 vs C12: 121±3, P<.001). We found a positive correlation between these two parameters. Moreover HF diet increased the release of vasoconstrictor prostanoids such as thromboxane (TX) B2 (ng PR/mg of tissue, HF8: 117±6 vs C8: 66±2 and HF12: 123±6 vs C12: 62±5, P<.001) and prostaglandin (PG) F2α (ng/mg, HF8: 153±9 vs C8: 88±3 and HF12: 160±11 vs C12: 83±5, P<.001). We also found that this increase in the release of vasoconstrictor prostanoids positively correlates with the elevation of SBP. In addition, HF diet increases the release of PGE2 and decreases the prostacyclin (PGI2 )/TXA2 release ratio at 8 and 12 weeks of treatment compared to control groups. In the HFMf group, metformin treatment prevented all these increases in mesenteric vascular bed adiposity index (%, HFMf8: 1.3±0.2 vs HF8 and HFMf12: 1.3±0.1 vs HF12, P<.05); SBP (mm Hg, HFMf8: 127±2 vs HF8 and HFMf12: 132±1 vs HF12, P<.001); TXB2 release (ng PR/mg of tissue, HFMf8: 65±12 vs HF8, P<.05 and HFMf12: 53±3 vs HF12, P<.001) and PGF2 α (ng PR/mg of tissue, HFMf8: 99±13 vs HF8, P<.01 and HFMf12: 77±8 vs HF12, P<.001). Meanwhile metformin prevented the increment in PGE2 release only at 12 weeks. On the other hand, metformin improved the PGI2 /TXA2 ratio in both periods studied. In conclusion, metformin could exert beneficial effects on adipose tissue and the vascular system by improving endothelial dysfunction induced by an imbalance of vasoactive substances in mesenteric perivascular adipose tissue in this model.

Adverse effects of tempol on hidrosaline balance in rats with acute sodium overload.

We studied the effects of tempol, an oxygen radical scavenger, on hydrosaline balance in rats with acute sodium overload. Male rats with free access to water were injected with isotonic (control group) or hypertonic saline solution (0.80 mol/l NaCl) either alone (Na group) or with tempol (Na-T group). Hydrosaline balance was determined during a 90 min experimental period. Protein expressions of aquaporin 1 (AQP1), aquaporin 2 (AQP2), angiotensin II (Ang II) and endothelial nitric oxide synthase (eNOS) were measured in renal tissue. Water intake, creatinine clearance, diuresis and natriuresis increased in the Na group. Under conditions of sodium overload, tempol increased plasma sodium and protein levels and increased diuresis, natriuresis and sodium excretion. Tempol also decreased water intake without affecting creatinine clearance. AQP1 and eNOS were increased and Ang II decreased in the renal cortex of the Na group, whereas AQP2 was increased in the renal medulla. Nonglycosylated AQP1 and eNOS were increased further in the renal cortex of the Na-T group, whereas AQP2 was decreased in the renal medulla and was localized mainly in the cell membrane. Moreover, p47-phox immunostaining was increased in the hypothalamus of Na group, and this increase was prevented by tempol. Our findings suggest that tempol causes hypernatremia after acute sodium overload by inhibiting the thirst mechanism and facilitating diuresis, despite increasing renal eNOS expression and natriuresis.

Regulation of Dopamine Uptake by Vasoactive Peptides in the Kidney.

Considering the key role of renal dopamine in tubular sodium handling, we hypothesized that c-type natriuretic peptide (CNP) and Ang-(1-7) may regulate renal dopamine availability in tubular cells, contributing to Na(+), K(+)-ATPase inhibition. Present results show that CNP did not affect either (3)H-dopamine uptake in renal tissue or Na(+), K(+)-ATPase activity; meanwhile, Ang-(1-7) was able to increase (3)H-dopamine uptake and decreased Na(+), K(+)-ATPase activity in renal cortex. Ang-(1-7) and dopamine together decreased further Na(+), K(+)-ATPase activity showing an additive effect on the sodium pump. In addition, hydrocortisone reversed Ang-(1-7)-dopamine overinhibition on the enzyme, suggesting that this inhibition is closely related to Ang-(1-7) stimulation on renal dopamine uptake. Both anantin and cANP (4-23-amide) did not modify CNP effects on (3)H-dopamine uptake by tubular cells. The Mas receptor antagonist, A-779, blocked the increase elicited by Ang-(1-7) on (3)H-dopamine uptake. The stimulatory uptake induced by Ang-(1-7) was even more pronounced in the presence of losartan, suggesting an inhibitory effect of Ang-(1-7) on AT1 receptors on (3)H-dopamine uptake. By increasing dopamine bioavailability in tubular cells, Ang-(1-7) enhances Na(+), K(+)-ATPase activity inhibition, contributing to its natriuretic and diuretic effects.

PCDHB14- and GABRB1-like nervous system developmental genes are altered during early neuronal differentiation of NCCIT cells treated with ethanol.

Ethanol (EtOH) exposure during embryonic development causes dysfunction of the central nervous system (CNS). Here, we examined the effects of chronic EtOH on gene expression during early stages of neuronal differentiation. Human embryonic carcinoma (NCCIT) cells were differentiated into neuronal precursors/lineages in the presence or absence of EtOH and folic acid. Gene expression profiling and pathway analysis demonstrated that EtOH deregulates many genes and pathways that are involved in early brain development. EtOH exposure downregulated several important genes, such as PCDHB14, GABRB1, CTNND2, NAV3, RALDH1, and OPN5, which are involved in CNS development, synapse assembly, synaptic transmission, and neurotransmitter receptor activity. GeneGo pathway analysis revealed that the deregulated genes mapped to disease pathways that were relevant to fetal alcohol spectrum disorders (FASD, such as neurotic disorders, epilepsy, and alcohol-related disorders). In conclusion, these findings suggest that the impairment of the neurological system or suboptimal synapse formation resulting from EtOH exposure could underlie the neurodevelopmental disorders in individuals with FASD.

Signaling pathways involved in renal oxidative injury: role of the vasoactive peptides and the renal dopaminergic system.

The physiological hydroelectrolytic balance and the redox steady state in the kidney are accomplished by an intricate interaction between signals from extrarenal and intrarenal sources and between antinatriuretic and natriuretic factors. Angiotensin II, atrial natriuretic peptide and intrarenal dopamine play a pivotal role in this interactive network. The balance between endogenous antioxidant agents like the renal dopaminergic system and atrial natriuretic peptide, by one side, and the prooxidant effect of the renin angiotensin system, by the other side, contributes to ensuring the normal function of the kidney. Different pathological scenarios, as nephrotic syndrome and hypertension, where renal sodium excretion is altered, are associated with an impaired interaction between two natriuretic systems as the renal dopaminergic system and atrial natriuretic peptide that may be involved in the pathogenesis of renal diseases. The aim of this review is to update and comment the most recent evidences about the intracellular pathways involved in the relationship between endogenous antioxidant agents like the renal dopaminergic system and atrial natriuretic peptide and the prooxidant effect of the renin angiotensin system in the pathogenesis of renal inflammation.

Diagnostic value of CA125 as a predictor of recurrence in advanced ovarian cancer.

PURPOSE: The aim of this study was to establish the guidelines for detecting early recurrences of advanced epithelial ovarian cancer by use of the CA-125 level. MATERIALS AND METHODS: Eighty-five of the patients who met the inclusion criteria were enrolled in this study. The authors examined 25 incremental changes of CA125 from one to 25 IU/ml, and compared the CA-125 value with other prognostic factors. Increases in the CA-125 level from the nadir level were expressed as CA-125- increments. RESULTS: Among the 25 increments, a CA-125-8 (eight IU/ml) was selected as the predictor that was the most efficient and time-effective. CA-125-8 had a sensitivity of 91.5%, a specificity of 84.6%, a positive predictive value of 93.1%, a negative predictive value of 81.5%, an efficiency of 89.4%. and a median lead-time of 68.5 days (p <0.0001). CONCLUSION: The authors suggest the incremented CA-125-8 as a predictor of recurrent advanced ovarian cancer.

Large nonlinear optical response of polycrystalline Bi3.25La0.75Ti3O12 ferroelectric thin films on quartz substrates.

We measure the nonlinear susceptibility of Bi(3.25)La(0.75)Ti(3)O(12) (BLT) thin films grown on quartz substrates using the Z-scan technique with picosecond laser pulses at a wavelength of 532 nm. The third-order nonlinear refractive index coefficient gamma and absorption coefficient beta of the BLT thin film are 3.1 x 10(-10) cm(2)/W and 3 x 10(-5) cm/W, respectively, which are much larger than those of most ferroelectric films. The results show that the BLT thin films on quartz substrates are good candidate materials for applications in nonlinear optical devices.

Piezoelectric and electromechanical properties of relaxor ferroelectric Pb(Mg1/3Nb2/3)O3(65%)-PbTiO3(35%) thin films observed by scanning force microscopy.

Relaxor ferroelectric PbMg(1/3)Nb(2/3)O(3)(65%)-PbTiO(3)(35%) (PMN-35PT) thin films were grown by a sol-gel method on Pt(111)/TiO(2)/SiO(2)/Si(100) substrates. Piezoresponse and poling behavior appear to have a relation with the relaxor behavior of the materials. Piezoelectric images were studied in a number of regions on the films with subsequent statistical analysis of the obtained data using the contact mode of scanning force microscopy. Hysteresis loops were observed with external field applied over a wide range of the vibration frequency. The piezoelectric coefficient, d(33), and the crystallographic electrostrictive constant, Q(33), were also determined as 100pm/V and 2.8x10(-3)C(-2)m(4), respectively.

Differential effects of forskolin and phobol 12-myristate-13-acetate on the c-fos and c-jun mRNA expression in rat C6 glioma cells.

The effects of forskolin (FSK) and phobol 12-myristate-13-acetate (PMA) on c-fos and c-jun mRNA expressions in rat C6 glioma cells were studied. Both FSK and PMA increased the c-fos mRNA level. The C-jun mRNA level was decreased by FSK, whereas it was increased by PMA. The elevated c-fos mRNA level, induced by FSK or PMA, was significantly inhibited by dexamethasone (DEX). In contrast, DEX did not affect the FSK- and PMA-induced response of the c-jun mRNA level. Cycloheximide (CHX) caused a superinduction of the FSK- or PMA-induced c-fos mRNA level. Furthermore, CHX also potentiated the PMA-induced c-jun mRNA level. However, CHX did not affect the FSK-induced down-regulation of the c-jun mRNA level. When C6 glioma cells were incubated with PMA and FSK, the PMA-induced c-jun mRNA level was inhibited by FSK, whereas FSK did not affect the PMA-induced c-fos mRNA level. Our results suggest that the activations of PKA and PKC pathways have different roles in the regulation of the c-jun mRNA expression in rat C6 glioma cells. PKA activation can inhibit induction of the c-jun mRNA expression by PMA. In addition, DEX appears to have a selective inhibitory action against c-fos, but not c-jun, -mRNA expression that is regulated by PKA and PKC. On-going protein synthesis inhibition is required for the superinduction of the c-fos expression that is induced by PMA, or FSK and the PMA-induced c-jun mRNA level.

The difference in perceptions of educational need between epilepsy patients and medical personnel.

PURPOSE: This study was undertaken to determine what patients with epilepsy need to know about their condition, and to discern what differences exist between patients' perceptions of this need and the medical profession's perception of what patients should know. METHODS: Seventy-five consecutive patients with epilepsy and 56 medical personnel (residents and nurses) who were working in either Neurology or Neurosurgery Units were studied using a structured questionnaire consisting of 3 subsets with a total of 27 questions. RESULTS: Using a Likert scale, epilepsy patients gave high priority to their need for more information about "how epilepsy is diagnosed," "the structure of the brain" (p < 0.05, p < 0.01, respectively), and "the diet that might prevent the attack" (p < 0.05) than did medical personnel. Our study also revealed that men were more concerned with questions regarding smoking and drinking than were women (p < 0.05, respectively), whereas married patients gave higher scores in the category of employment (p < 0.01) and contraception/pregnancy (p < 0.05) than did unmarried patients. The patients with one or more seizures per month rated higher scores on questions concerning the first aid at the time of attack and dosage of antiepileptic drugs (AEDs; p < 0.05, respectively) than did the patients with fewer than one seizure per month. The patients taking poly-AED treatment gave higher scores on six items related to AED therapy than did those receiving monotherapy. No significant differences were found with regard to the length of time patients had the condition, nor to educational level or current employment status. CONCLUSIONS: An educational program for epilepsy patients should be developed on the basis of understanding that there are differences in perspectives among patients with different sociocultural contexts as well as between patients and medical personnel.

Possible roles of JNK pathway in the regulation of hippocampal proenkephalin and immediate early gene expression induced by kainic acid.

Mitogen-activated protein kinases (MAPKs) may play crucial roles in the kainic acid (KA)-evoked excitotoxic effect and the regulation of transcription factors (e.g. c-Fos and c-Jun) in hippocampus, but their exact role in the regulation of KA-induced opioid peptides expression has not been well characterized in vivo. Therefore, we examined possible involvement of the phosphorylated form of JNK, as well as CREB, in the regulation of KA-induced proenkephalin and immediate early genes (IEGs) expression in the rat hippocampus. KA increased proenkephalin mRNA expression in rat hippocampus, which was decreased by pre-administration with cycloheximide (CHX, a protein synthesis inhibitor). KA alone increased c-fos as well as c-jun mRNA levels. CHX further enhanced KA-induced c-fos and c-jun mRNA levels. Additionally, KA increased the phosphorylation of JNK, especially JNK1, which was attenuated by CHX. CHX decreased KA-induced c-Fos protein expression. Interestingly, CHX itself increased the phosphorylation of CREB, which was abolished by KA administration. Our results suggest that the phosphorylation of JNK is involved in the up-regulation of the proenkephalin gene expression via c-Fos and c-Jun that is induced by KA in rat hippocampus. However, the phosphorylation of CREB is not associated with the up-regulation of the proenkephalin mRNA level induced by KA in the rat hippocampus.

Stimulation of astrocyte-enriched culture with C2 ceramide increases proenkephalin mRNA: involvement of cAMP-response element binding protein and mitogen activated protein kinases.

In rat astrocyte-enriched culture, C2 ceramide dose- and time-dependently increased proenkephalin (proENK) mRNA; the significant increase began at 6 h after 30 microM C2 ceramide treatment (about 13-fold) and at 12 h after treatment (about 21-fold). In addition, C2 ceramide also increased AP-1 proteins, such as Fra-1, c-Jun, JunB and JunD, and phosphorylation of CREB. The blocking of protein synthesis by cycloheximide (CHX) evokes a further increase of C2 ceramide-induced proENK mRNA and phospho-CREB level, while C2 ceramide-induced increases of AP-1 protein levels were reduced by CHX. The C2 ceramide-induced proENK mRNA expression was not changed significantly by the pretreatment with H89 (a PKA inhibitor), KN62 (a calcium/calmodulin-dependent protein kinase II inhibitor), and PD98059 (an ERK pathway inhibitor). However, calphostin C (a PKC inhibitor) and or SB203580 (a p38 inhibitor) partially but significantly reduced C2 ceramide-induced proENK mRNA expression as well as phospho-CREB level. These results suggest that, in the rat astrocyte-enriched culture, C2 ceramide increases proENK mRNA expression via phosphorylation of CREB rather than the increases of AP-1 protein levels. Additionally, the activations of PKC and p38, but not PKA, calcium/calmodulin-dependent protein kinase II, and ERK, by C2 ceramide play important regulatory roles in C2 ceramide-induced proENK mRNA expression via activating the CREB.

Supraspinal NMDA and non-NMDA receptors are differentially involved in the production of antinociception by morphine and beta-endorphin administered intracerebroventricularly in the formalin pain model.

Our previous studies have demonstrated that supraspinal glutamate receptors are differentially involved in the antinociception induced by morphine and beta-endorphin given intracerebroventricularly (i.c.v.) in the tail-flick and hot-plate tests. The formalin pain test was used in the present study. Injection of mice with formalin solution (2%, 10 microl) into the hindpaw intraplantarly produced the first (0-5 min) and second (20-40 min) phases of formalin responses. The formalin responses in the both phases were attenuated dose-dependently by morphine (0.125-1 microg) or beta-endorphin (0.125-1 microg) administered i.c.v. 5 min before. The antinociceptive effect of morphine was slightly more potent in the second phase whereas the effect of beta-endorphin was more pronounced in the first phase. MK-801 (0.1-1 microg), a non-competitive NMDA receptor antagonist, and CNQX (0.05-0.5 microg), a non-NMDA antagonist, given i.c.v., produced antinociceptive effect in the both phases, but only in a partial manner. Both MK-801 (0.05 microg) and CNQX (0.01 microg), at the dose which had no intrinsic effect, reversed the antinociceptive effect of beta-endorphin (1 microg) observed during the second, but not the first, phase partially but significantly. However, the antinociceptive effect of morphine (1 microg) was not affected by the same dose of MK-801 or CNQX given i.c.v. Our results indicate that, at the supraspinal level, both NMDA and non-NMDA receptors are involved in the production of antinociception induced by supraspinally administered beta-endorphin, but not morphine, in the formalin pain model.

Regulation of c-fos gene expression by lipopolysaccharide and cycloheximide in C6 rat glioma cells.

The effect of lipopolysaccharide (LPS) on the expression of immediate early genes, such as c-fos and c-jun, was examined in C6 rat glioma cells. LPS (1 microg/ml) alone did not affect c-fos mRNA level. LPS, however, transiently increased c-jun mRNA level. Cycloheximide (CHX, 20 microM), a protein synthesis inhibitor, alone caused increases of c-fos and c-jun mRNA levels. LPS showed a potentiating effect in the regulation of c-fos mRNA level, whereas LPS showed an additive action for the regulation of CHX-induced c-jun mRNA expression. To determine if CREB and mitogen-activated protein kinases (MAPKs) are involved in the regulation of c-fos mRNA expression by LPS and CHX, Western blot was carried out using the phosphorylated form of antibodies against ERK, JNK, p38, and CREB. LPS transiently increased the phosphorylation of p38-MAPK and CREB. In addition, LPS alone elevated phosphorylation of ERK (p44/p42) MAPK in a time-dependent manner. Furthermore, LPS plus CHX enhanced phosphorylation of ERK, p38, and CREB in a synergistic manner. Our results suggest that the phosphorylation of ERK, p38, and CREB may be involved in the regulation of synergistic c-fos mRNA expression induced by LPS plus CHX in C6 rat glioma cells.

Differential effects of cholera toxin and pertussis toxin on the c-fos and c-jun mRNA expression in rat C6 glioma cells.

Cholera toxin (CTX) increased c-fos mRNA level whereas it down-regulated the c-jun mRNA level in rat C6 glioma cells. In contrast to the action of CTX, pertussis toxin (PTX) did not affect either c-fos or c-jun mRNA level. The elevated c-fos mRNA level induced by CTX was significantly inhibited by the co-treatment with dexamethasone (DEX). However, DEX did not affect CTX-induced down-regulation of c-jun mRNA level. Cycloheximide (CHX) increased c-fos and c-jun mRNA levels. CHX caused a super-induction of CTX-induced c-fos mRNA level. Our results suggest that CTX-, but not PTX-, sensitive G-proteins may play an important role for c-fos mRNA up-regulation and c-jun mRNA down-regulation. In addition, DEX appears to have a selective inhibitory action against c-fos mRNA expression regulated by CTX. Ongoing protein synthesis inhibition is required for the superinduction of c-fos, but not c-jun, mRNA induced by CTX.

Differential modulatory roles of cholera toxin and pertussis toxin in the regulation of pain responses induced by excitatory amino acids administered intrathecally in mice.

The present study was designed to characterize the possible roles of spinally located cholera toxin (CTX)- and pertussis toxin (PTX)-sensitive G-proteins in excitatory amino acids induced pain response. Intrathecal (i.t.) injection of glutamate (20 microg), N-methyl-D-aspartic acid (NMDA; 60 ng), alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA; 13 ng), and kainic acid (12 ng) showed pain response. Pretreatment with CTX (0.05 and 0.5 microg, i.t.) attenuated pain response induced by glutamate, NMDA, AMPA and kainic acid administered i.t. in a dose-dependent manner. On the other hand, i.t. pretreatment with PTX further increased the pain response induced by glutamate, NMDA, AMPA and kainic acid administered i.t., especially at the dose of 0.5 microg. Our results suggest that, at the spinal cord level, CTX- and PTX-sensitive G-proteins appear to play opposite roles in modulating the pain response induced by spinally administered. Furthermore, CTX- and PTX-sensitive G-proteins appear to modulate pain response induced by stimuli of both NMDA and non-NMDA glutamate receptors.

Cycloheximide increases proenkephalin and tyrosine hydroxylase gene expression in rat adrenal medulla.

The effect of cycloheximide (CHX; 5 mg/kg) on proenkephalin (proENK) and tyrosine hydroxylase (TH) mRNA expression in rat central and peripheral nervous systems was studied. CHX increased proENK and TH mRNA levels in the adrenal gland, but not in hippocampus, striatum, midbrain, brainstem, pituitary, and hypothalamus. The pretreatment with actinomycin D (0.5 mg/kg) significantly decreased CHX-induced proENK and TH mRNA expression, suggesting that the CHX-dependent increase of these mRNA levels may be caused by the increase of transcriptional activity rather than RNA stabilization. To investigate the factors involved in CHX-induced proENK and TH mRNA expression, the effect of CHX on activator protein-1 (AP-1), cAMP response element (CRE) binding protein (CREB), and glucocorticoid response element (GRE) was tested. In AP-1, the basal expression of Fra-2 and c-Jun proteins and AP-1 DNA binding activity in the adrenal medulla was higher than other tissues tested, but CHX reduced these protein levels and AP-1 DNA binding activity. In CREB, CHX time dependently increased the level of phospho-CREB without altering total CRE level and CRE DNA binding activity. Furthermore, phospho-CREB actively participated in CRE DNA binding activity. In GRE, although CHX increased plasma and adrenal corticosterone level, RU486 (10 mg/kg) reduced CHX-induced proENK, but not TH, mRNA level in a partial manner. These results suggest that the basal expression of proENK and TH mRNA transcription in the adrenal gland seems to be tonically inhibited by de novo protein synthesis. In addition, CHX-dependent increase of proENK and TH mRNA expression in the adrenal medulla is well correlated with phospho-CREB level, but not AP-1. Finally, glucocorticoid seems to be involved at least partially in CHX-dependent proENK, but not TH, mRNA expression in the adrenal medulla.

Activation of adenylate cyclase results in down-regulation of c-jun mRNA expression in rat C6 glioma cells.

To investigate the possible mechanisms involved in forskolin-induced c-jun mRNA decrease in rat C6 glioma cells, we examined effects of a PKA inhibitor (H-89), a L-type Ca2+ channel blocker (nimodipine), a calmodulin activation inhibitor (calmidazolium chloride) and a Ca2+/calmodulin-dependent protein kinase II inhibitor (KN-62) on forskolin-induced c-jun mRNA down-regulation. H-89 caused a reversal of forskolin-induced c-jun mRNA decrease. Furthermore, nimodipine, KN-62 and calmidazolium chloride partially blocked forskolin-induced c-jun mRNA down-regulation. Our results suggest that activation of adenylate cyclase appears to be involved in a down-regulation of c-jun mRNA expression through a PKA pathway. In addition, L-type calcium channels, calmodulin and Ca2+/calmodulin-dependent protein kinase II may be partially involved in c-jun mRNA down-regulation induced by forskolin.