Transcranial static magnetic stimulation reduces seizures in a mouse model of Dravet syndrome

Dravet syndrome is a rare form of severe genetic epilepsy characterized by recurrent and long-lasting seizures. It appears around the first year of life, with a quick evolution toward an increase in the frequency of the seizures, accompanied by a delay in motor and cognitive development, and does not respond well to antiepileptic medication. Most patients carry a mutation in the gene SCN1A encoding the α subunit of the voltage-gated sodium channel Nav1.1, resulting in hyperexcitability of neural circuits and seizure onset. In this work, we applied transcranial static magnetic stimulation (tSMS), a non-invasive, safe, easy-to-use and affordable neuromodulatory tool that reduces neural excitability in a mouse model of Dravet syndrome. We demonstrate that tSMS dramatically reduced the number of crises. Furthermore, crises recorded in the presence of the tSMS were shorter and less intense than in the sham condition. Since tSMS has demonstrated its efficacy at reducing cortical excitability in humans without showing unwanted side effects, in an attempt to anticipate a possible use of tSMS for Dravet Syndrome patients, we performed a numerical simulation in which the magnetic field generated by the magnet was modeled to estimate the magnetic field intensity reached in the cerebral cortex, which could help to design stimulation strategies in these patients. Our results provide a proof of concept for nonpharmacological treatment of Dravet syndrome, which opens the door to the design of new protocols for treatment.

Pathway Analysis of Transcriptional Alterations in the Salivary Gland Following Radiation Exposure

PURPOSE/OBJECTIVE(S)

Radiation-induced xerostomia (RIX) is the subjective condition of dry mouth caused by radiation therapy to the head and neck and a result of hyposalivation and altered sialochemistry. Our long-term goal is to develop novel approaches to improve salivary function after radiation therapy. To better understand the molecular alterations induced by radiation in the salivary glands, we performed transcriptional profiling aimed at describing acute and long-term alterations in the murine salivary glands induced by radiation to better design effective regenerative therapies.

MATERIALS/METHODS

The submandibular gland (SMG) of male C57Bl/6 mice received 15 Gy in a single fraction using a small animal image-guided irradiator. The mice were followed for 90 days. Saliva was collected at baseline and 7, 60 and 90 days after radiation. Salivary glands were collected for histology 3, 7, 60, and 90 days after radiation. The tissues were analyzed using a multiplex analysis platform processed with the murine whole transcriptome panel to investigate changes in gene expression over time. Using the multiplex analysis platform software, 96 regions of interest corresponding to acini, ducts, and granular convoluted tubules (GCTs) were delineated and gene expression was assessed separately in each area. To confirm the identified alterations, SMG tissue was histologically evaluated for fibrosis (masons tri-chrome), mucin (alcian blue), and amylase (α-amylase). Alterations in the immune microenvironment (CD19, CD3, and F4/80) and salivary gland stem cells (MIST1, SCA, Sox2, and c-Kit) were assessed by immunohistochemistry.

RESULTS

Radiation resulted in a significant decrease in salivary production compared to nonirradiated controls (p-value = 0.03). The analysis of the transcriptional pathway identified early alterations in cell communication, DNA damage, and the immune response. Protein metabolism and extracellular matrix remodeling were up-regulated at later time points. Histological evaluation of tissues showed an increase in glandular structure disorganization over time, with a decrease in the size and distribution of the acinar compartments throughout the gland (mean area stained: No RT = 25.81% vs 90d RT = 19.98%, p-value = 0.005). There was an increase in periductal fibrosis within the tissue after 60 days compared to controls. Acutely, there was an increase in the expression of MIST1 and macrophages (mean area stained: No RT = 14.8% vs 7d RT = 18.76%, p-value = 0.0004) within the SMG that had resolved by the 60- and 90-day time points.

CONCLUSION

The results implicate macrophage alterations in radiation-induced salivary gland damage and provide valuable mechanistic insight guiding potential approaches to intervene in RIX. We are pursuing cell therapy-based approaches to prevent and repair damage caused by radiation in order to improve the lives of our patients.

Numerical Study of a Thrombus Migration Risk in Aneurysm After Coil Embolization in Patient Cases: FSI Modelling

PURPOSE

There are still many challenges for modelling a thrombus migration process in aneurysms. The main novelty of the present research lies in the modelling of aneurysm clot migration process in a realistic cerebral aneurysm, and the analysis of forces suffered by clots inside an aneurysm, through transient FSI simulations.

METHODS

The blood flow has been modelled using a Womersley velocity profile, and following the Carreau viscosity model. Hyperelastic Ogden model has been used for clot and isotropic linear elastic model for the artery walls. The FSI coupled model was implemented in ANSYS® software. The hemodynamic forces suffered by the clot have been quantified using eight different clot sizes and positions inside a real aneurysm.

RESULTS

The obtained results have shown that it is almost impossible for clots adjacent to aneurysm walls, to leave the aneurysm. Nevertheless, in clots positioned in the centre of the aneurysm, there is a real risk of clot migration. The risk of migration of a typical post-coiling intervention clot in an aneurysm, in contact with the wall and occupying a significant percentage of its volume is very low in the case studied, even in the presence of abnormally intense events, associated with sneezes or impacts.

CONCLUSIONS

The proposed methodology allows evaluating the clot migration risk, vital for evaluating the progress after endovascular interventions, it is a step forward in the personalized medicine, patient follow-up, and helping the medical team deciding the optimal treatment.

Efficacy of psychological interventions for young adults with mild-to-moderate depressive symptoms: A meta-analysis

BACKGROUND

Psychological interventions are commonly used to treat mild-to-moderate depression, but their efficacy in young adults has not been exhaustively addressed. This meta-analysis aims to establish it in comparison to no treatment, wait-list, usual treatment, passive interventions, and other bona-fide treatments.

METHODS

The search was conducted in Scopus, MEDLINE, PsycINFO, ClinicalTrials.gov, the ISRCTN Registry, Cochrane CENTRAL, Clarivate BIOSIS Previews and the METAPSY database, retrieving studies from the start of records to April 2020. Eligibility criteria included samples of 16-30 years experiencing mild-to-moderate depressive symptoms and participating in randomized controlled trials (RCTs), non-RCTs, or pre-post studies measuring depressive symptomatology and featuring psychological treatments.

RESULTS

Up to 45 studies met criteria, consisting of 3,947 participants, assessed using the Quality Assessment Tool for Quantitative Studies and their results meta-analyzed assuming random effects. Psychological interventions proved to be efficacious in RCTs compared to no treatment (g = -0.68; 95% CI = -0.87, -0.48) and wait-list (g = -1.04; 95% CI = -1.25, -0.82), while depressive symptoms also improved in pre-post studies (g = -0.99; 95% CI = -1.32, -0.66). However, intervention efficacy was similar to usual care, passive, and bona-fide comparators. The heterogeneity found, a likely reporting bias and the low quality of most studies must be considered when interpreting these results.

CONCLUSIONS

Psychological treatments are efficacious to reduce depressive symptoms in young adults, but comparable to other interventions in the mild-to-moderate range. Moderators like depression severity or therapist involvement significantly influenced their efficacy, with results encouraging clinicians to adopt flexible and personalized approaches.

The effects of Cumulative Trauma and Cognitive Rigidity on the Severity of Depressive Disorder: Preliminary Results

Introduction

The long-lasting effects of trauma on mental health and the cumulative effect during the lifetime is one of the great interest in research and applied psychology. However, the effect of cumulative trauma in combination with cognitive biases, such as cognitive rigidity (“all-or-nothing” thinking pattern), on the severity of depression has not been tested yet.

Objectives

The aim of this study was to analyse these variables, while considering for differential gender effects on a sample of patients with the diagnosis of depressive disorder.

Methods

A total sample of 177 patients (137 women) were assessed using the Cumulative Trauma Scale. Cognitive rigidity was measured with the Repertory Grid Technique and severity of depressive symptoms with the Beck Depression Inventory.

Results

indicated that high levels of cognitive rigidity and high frequency of perceived negative cumulative trauma predicted depressive symptoms; while high frequency of perceived positive trauma did not predict depressive symptoms. Moreover, gender did not explain variability of depression, and its interaction with frequency of perceived trauma was not significant.

Conclusions

Overall, traumatic cumulative trauma frequency and its negative appraisal are key to the understanding the severity of depression but also cognitive rigidity seemed to be a relevant factor to consider. Thus, these results highlight the need to focus on traumatic and cognitive aspects to increase the efficacy of psychological interventions in depression.

Disclosure

No significant relationships.

Personal construct therapy vs. cognitive behavioural therapy in the treatment of depression in women with fibromyalgia: a multicentre randomized controlled trial with a 6-month follow-up

Introduction

Depressive symptoms are common in patients with Fibromyalgia (FM), a chronic and disabling pain syndrome. Psychological interventions are mostly focused in negative thinking and behavioural activation. However, several studies suggest that personal identity is also affected by FM.

Objectives

We aimed to examine the effects of Personal Construct Therapy (PCT), an idiographic approach that emphasizes identity features and interpersonal construal, on depressive symptoms in women with FM.

Methods

In the context of a multicentre parallel randomized trial (Trial Registry: NCT02711020), 106 women with FM and presenting depressive symptoms were randomized either to either Cognitive Behavioural Therapy (CBT; n = 55), taken as a gold standard comparison, or PCT (n = 51). In total, 69 patients completed the treatment and the six-month follow-up assessment (CBT = 32 and PCT = 37). Both treatments were applied on case formulation premises.

Results

Linear mixed-effects models were performed to compare depressive symptoms between treatment conditions. Anxiety and pain measures were treated as secondary outcomes. Participants in both conditions significantly reduced their levels of depression and anxiety as well as the impact of FM but no significant between treatment differences were found. Analysis of clinically significant change for depressive symptoms and pain was also similar between both conditions.

Conclusions

PCT resulted equally effective in the treatment of depressive symptoms in women with FM when compared with CBT, both offered in a modular format. Thus, PCT with tis focus on identity issues can be considered as an alternative treatment for these patients.

Disclosure

No significant relationships.

Levels of intervention and support for newly presenting clients with eating disorders

Introduction

Clients with Eating Disorders may be treated as inpatients (IP), day hospital (DH) or community patients (Ambu). The ITAMITED study is following to treatment termination (or end of October 2025) all new clients with EDs presenting between November 2017 and October 2020 to eight centres in Spain.

Objectives

To describe to what extent initial care levels (IP, DH, Ambu) are associated with gender, age, social relationships, ED diagnosis Body Mass Index (BMI) and baseline medication.

Methods

The study is exploratory/descriptive, practice-based evidence (PBE). Consecutive new clients were approached for participation. Inclusion criteria were a diagnosis of an ED and opting in to treatment.

Results

The only variables not showing a statistically significant relationship with level were gender (no relationship), diagnosis of bulimia and use of prescribed psychostimulant medication (which was rare). OP care was associated with older age which did not discriminate between DH and IP. Similarly, being in a relationship was associated with OP care but didn’t differentiate between DH and OP. Relationships with ED diagnosis other than AN type I were complex but significant. Relationships with AN type I, BMI and being on antipsychotics, antidepressants, anxiolytics, mood stabilisers and a catch-all category of all other medication all showed an ordered relationship IP > DH > Ambu. The most powerful relationships were with BMI and diagnosis of AN type I.

Conclusions

Initial level of care is associated with many factors and strongly with many of them. This will complicate the analyses of trajectories of change but reflects the heterogeneity of this client group.

Disclosure

I am Clinical Director of ITA but analyses are prespecified. Evans, Medina and Paz are not remunerated by ITA nor related to ITA or any of its employees they would counter any pressure on analyses or reporting that might arise from my position.

Self-report questionnaires in eating disorders: do we need to be careful interpreting self-report in conditions with self-perception issues?

Introduction

A major revolution in psychiatry since the late 20th and early 21st Century has sought to put the individual client at the heart of intervention, promoting shared decision making. Increasing use of patient reported outcome measures (PROMs) to evaluate interventions and even steer therapies (“power assisted steering for psychotherapy”, Evans 2012) appears congruent with this. But is caution needed interpreting PROMS where self-perception distortions form a core part of the client’s problem? Eating disorders are a paradigmatic test.

Objectives

To see if PROM scores at initial presentation at services for ED seemed congruent with help-seeking. We report CORE-Outcome scores here.

Methods

Inclusion criteria were a diagnosis of an ED and opting in to treatment. Consecutive new clients at all the centres were approached for participation. Scores distributions were analysed to see if numbers of low scores, “non-clinical range” scores seemed congruent with help-seeking.

Results

18% of the participants who completed the CORE-OM at baseline had a score below the Clinically Significant Change (CSC) cutting point. Though the rate was higher in participants with an Anorexia type I diagnosis (22.6%) than those with other ED diagnoses (15.8%): in the expected direction, the difference was narrowly non-significant (chi-squared = 3.5, d.f. = 1, p = .06). Scores did relate to treatment level.

Conclusions

The predicted elevated rate of non-clinical baseline scores in the AN1 group was narrowly non-significant but the rate of 18% non-clinical scores in a help-seeking population raises a cautionary message about interpretation of change from initially low scores.

Disclosure

I am one of the three trustees of CORE System Trust which holds the copyright on the CORE measures used in this study but the measures are all provided under a Creative Commons licence so I receive no remuneration from this.

FSI modeling on the effect of artery-aneurysm thickness and coil embolization in patient cases

BACKGROUND AND OBJECTIVE

The attainment of a methodology to simulate the hemodynamic in patient-specific cerebral vessels with aneurysms is still a challenge. The novelty of this work is focused on the effect of coil embolization in a realistic cerebral aneurysm, according to the vessel wall thickness and aneurysm thickness, through transient FSI simulations.

METHODS

The quality of the mesh for simulations was checked with a specific mesh convergence study; and the numerical methodology was validated using numerical research data of the literature. The model was implemented in ANSYS® software. The total deformation and equivalent stress evolution in the studied cases, before and after coil embolization, were compared. More than 20 different models were employed due to different arterial wall thickness and aneurysm wall thickness combinations.

RESULTS

The obtained results have showed that deformation and stress values are highly influenced with the sac thickness. The thinner sac aneurysm thickness is, the greater deformation and stress are. The results after coil embolization process have highlighted that considering typical values of arterial wall thickness and aneurysm thickness 0.3 mm and 0.15 mm respectively, a deformation reduction around 50% and a stress reduction around 70% can be achieved.

CONCLUSIONS

The proposed methodology is a step forward in the personalized medicine, quantifying the aneurysm rupture risk reduction, and helping the medical team in the preoperative planning, or to deciding the optimal treatment.

Common and differential dimensions of personal identity between psychosis and depression: The relevance of gender and depressive mood

Disturbances in personal identity are recognized in psychosis and depression. However, it is unknown whether these disruptions share common processes across clinical groups, or whether there are unique alterations by group or between men and women within each clinical group. To advance on this question, we compared personal identity dimensions in psychosis and depression and investigated the effects of gender and depressive mood. This study assessed dimensions of personal identity using the repertory grid technique among 85 outpatients with psychosis, 85 outpatients with depressive disorders and 85 healthy controls who were matched by age. Data regarding depressive mood and general functioning was also collected. Results showed that self-discrepancies were higher in psychosis and depression than in controls, and were associated with depressive mood. Interpersonal dichotomous thinking was more prevalent in women in both clinical groups. Women with psychosis showed higher ideal-others discrepancy and had a more complex structure of personal identity than their male counterparts. To conclude, alterations in self-ideal and self-others discrepancies may be transdiagnostic dimensions related to depressive mood. Interpersonal dichotomous thinking may also be a common dimensional characteristic in psychosis and depression but more specific to women. Finally, critical views of others and a higher complexity of personal identity may be more specific to women than men with psychosis. Our results are consistent with other studies pointing to the need for person-focused treatments promoting the recovery of a full sense of personal identity, rather than just focusing on specific thoughts and feelings.

Valproic acid alters mitochondrial cholesterol transport in Y1 adrenocortical cells

Several reports suggest putative interactions between valproic acid (VPA) treatment and the hypothalamus-pituitary-adrenal axis. Given that VPA alters mitochondrial functions, an action of this drug on a mitochondrial process such as steroid synthesis in adrenal cells should be expected. In order to disclose a putative action of VPA on the adrenocortical cell itself we evaluated VPA effects on regulatory steps of the acute stimulation of steroidogenesis in Y1 adrenocortical cells. This study demonstrates that VPA increases progesterone production in non-stimulated cells without inducing the levels of Steroidogenic Acute Regulatory (StAR) protein, which facilitates cholesterol transport. This result suggests that VPA increases mitochondrial cholesterol transport through a StAR-independent mechanism and is further supported by the fact that in isolated mitochondria VPA stimulates exogenous cholesterol metabolization to progesterone. VPA also reduces the cAMP-mediated increase of the StAR protein, mRNA levels, promoter activity and progesterone production. In summary, the present data show that VPA can alter steroid production in adrenal cells by a complex mechanism that mainly involves an action on cholesterol access to the inner mitochondrial membrane. The VPA-mediated increase of basal steroidogenesis could be linked to the increase of basal cortisolemia described in patients under VPA treatment.

Enzymes involved in arachidonic acid release in adrenal and Leydig cells

Stimulation of receptors and subsequent signal transduction results in the activation of arachidonic acid (AA) release. Once AA is released from phospholipids or others esters, it may be metabolized via the cycloxygenase or the lipoxygenase pathways. How the cells drive AA to these pathways is not elucidated yet. It is reasonable to speculate that each pathway will have different sources of free AA triggered by different signal transduction pathways. Several reports have shown that AA and its lipoxygenase-catalyzed metabolites play essential roles in the regulation of steroidogenesis by influencing cholesterol transport from the outer to the inner mitochondrial membrane, the rate-limiting step in steroid hormone biosynthesis. Signals that stimulate steroidogenesis also cause the release of AA from phospholipids or other esters by mechanisms that are not fully understood. This review focuses on the enzymes of AA release that impact on steroidogenesis.

Physiological importance of a circadian clock outside the suprachiasmatic nucleus

Circadian clocks are widely distributed in mammalian tissues, but little is known about the physiological functions of clocks outside the suprachiasmatic nucleus of the brain. The retina has an intrinsic circadian clock, but its importance for vision is unknown. Here, we show that mice lacking Bmal1, a gene required for clock function, had abnormal retinal transcriptional responses to light and defective inner retinal electrical responses to light, but normal photoreceptor responses to light and retinas that appeared structurally normal as observed by light and electron microscopy. We generated mice with a retina-specific genetic deletion of Bmal1, and they had defects of retinal visual physiology essentially identical to those of mice lacking Bmal1 in all tissues and lacked a circadian rhythm of inner retinal electrical responses to light. Our findings indicate that the intrinsic circadian clock of the retina regulates retinal visual processing in vivo.

Expression of pannexin1 in the CNS of adult mouse: cellular localization and effect of 4-aminopyridine-induced seizures

The expression pattern of pannexin1, a gene coding for a protein that forms gap junction channels, was studied as both mRNA and protein in the CNS of adult mouse. Pannexin1 was widely expressed in the CNS by neuronal cell types but not glial cells, except for Bergmann glial cells of the cerebellar cortex. Cells positive to Ca-binding proteins, principally parvalbumin, but also calbindin and calretinin, as well as glutamate decarboxylase 67 kDa isoform, were pannexin1-positive. Pannexin1 labeling was found in cells which are known to exhibit spontaneous and synchronous discharge, such as neurons of the inferior olivary complex and the reticular thalamic nucleus, and also in neurons whose electrical activity is not coupled with neighboring cells, such as motoneurons of the spinal cord. The analysis of cellular localization showed puncta that surrounded cell bodies (e.g. the pyramidal cells of hippocampus) or restricted areas inside the cell bodies (e.g. the spinal motoneurons). In Bergmann glial cells the staining was present as fine grains that covered a large part of the cellular surface. Pannexin1 stained cells that previous studies have reported as expressing connexin36, another protein forming gap junction channels. Thus, it was possible that these two proteins could be integrated in the same functions. Since connexin36 expression levels change after seizures, we examined the expression of both pannexin1 and connexin36 in cerebral cortex, hippocampus, cerebellum and brain stem at different time intervals (2, 4 and 8 h) after i.p. injection of 4-aminopyridine, which resulted in systemic seizures. The only modification of the expression levels observed in this study concerned the progressive decrement of the connexin36 in the hippocampus, while pannexin1 expression was unchanged. This finding suggested that pannexin1 and connexin36 are involved in different functional roles or that they are expressed in different cell types and that only those expressing the Cx36 are induced to apoptosis by epileptic seizures.

Arachidonic acid regulation of steroid synthesis: new partners in the signaling pathway of steroidogenic hormones

Although the role of arachidonic acid (AA) in trophic hormone-stimulated steroid production in various steroidogenic cells is well documented, the mechanism responsible for AA release remains unknown. We have previously shown evidence of an alternative pathway of AA generation in steroidogenic tissues. Our results are consistent with the hypothesis that, in steroidogenic cells, AA is released by the action of a mitochondrial acyl-CoA thioesterase (MTE-I). We have shown that recombinant MTE-I hydrolyses arachidonoyl-CoA to release free AA. An acyl-CoA synthetase specific for AA, acyl-CoA synthetase 4, has also been described in steroidogenic tissues. In the present study we investigate the new concept in the regulation of intracellular levels of AA, in which trophic hormones can release AA by mechanisms different from the classical PLA2-mediated pathway. Inhibition of ACS4 and MTE-I activity by triacsin C and NDGA, respectively results in a reduction of StAR mRNA and protein abundance. When both inhibitors are added together there is a synergistic effect in the inhibition of StAR mRNA, StAR protein levels and ACTH-stimulated steroid synthesis. The inhibition of steroidogenesis produced by the NDGA and triacsin C can be overcome by the addition of exogenous AA. In summary, results shown here demonstrate a critical role of the acyl-CoA synthetase and the acyl-CoA thioesterase in the regulation of AA release, StAR induction, and steroidogenesis. This further suggests a new concept in the regulation of intracellular distribution of AA through a mechanism different from the classical PLA2-mediated pathway that involves a hormone-induced acyl-CoA synthetase and a hormone-regulated acyl-CoA thioesterase.

Molecular events triggered by heat shock in Y1 adrenocortical cells

Several stimuli, including stress conditions, promote the activation of MAP kinases family members (ERK1/2, JNK, p38). In turn, these enzymes regulate several cellular functions. Given that MAPK activation requires the phosphorylation of these proteins, their inactivation depends on the activity of specific phosphatases. MAPK phosphatase-1 (MKP-1), a phosphatase specifically involved in the inactivation of MAPK family members, is induced by mitogenic stimuli and stress conditions. Here we describe the effect of heat shock (HS), 10 min, 45 degrees C, on MAPKs activities and MKP-1 mRNA and protein levels in Y1 adrenocortical cells. Western blot analysis performed with antibodies against the phosphorylated forms of ERK1/2 and JNK revealed that HS produced the rapid activation of these kinases. Their inactivation was also a rapid event and occurred together with the increase of MKP-1 protein levels detected by Western blot analysis. In addition, the effect of HS on MKP-1 protein levels seems to be exerted at the transcriptional level, since the amount of its mRNA in heat shocked cells was higher than in nonheated cells. Comparison of the temporal profiles of MKP-1 protein induction and MAPKs phospho-dephosphorylation suggests that MKP-1 induction could contribute to ERK1/2 and JNK inactivation after HS.

Protein tyrosine phosphatases are involved in LH/chorionic gonadotropin and 8Br-cAMP regulation of steroidogenesis and StAR protein levels in MA-10 Leydig cells

The LH signal transduction pathway features the activation of protein tyrosine phosphatases (PTPs) as one of the components of a cascade that includes other well characterized events such as cAMP-dependent protein kinase A (PKA) activation. Moreover, the action of PTPs is required to increase the rate-limiting step in steroid biosynthesis, namely the cAMP-regulated transfer of cholesterol to the inner mitochondrial membrane. Since both PKA activity and steroidogenic acute regulatory (StAR) protein induction are obligatory steps in this transfer of cholesterol, the present study was performed to investigate the role of PTPs in the regulation of PKA activity and StAR expression in response to LH/chorionic gonadotropin (CG) and 8Br-cAMP in MA-10 cells. While the exposure of MA-10 cells to the PTP inhibitor, phenylarsine oxide (PAO), did not modify PKA activity, it partially inhibited the effect of human CG and cAMP analog on StAR protein levels. Time-course studies demonstrated that PAO inhibited cAMP induction of StAR protein and mRNA. At 30 min, the effect on cAMP-stimulated StAR protein levels was a 35% inhibition, progressing to up to 90% inhibition at 120 min of stimulation. The maximal inhibitory effect on cAMP-induced StAR mRNA level was obtained at 60 min (85%). In summary, these results demonstrate that inhibition of PTP activity affected both StAR protein and mRNA synthesis and suggest that the activity of hormone-regulated PTPs is a requirement in the LH signaling cascade that results in the up-regulation of StAR protein and, subsequently, increased steroid synthesis.

The obligatory action of protein tyrosine phosphatases in ACTH-stimulated steroidogenesis is exerted at the level of StAR protein

A key regulatory step in the steroidogenic hormones signaling pathway is the synthesis of steroidogenic acute regulatory protein (StAR). This protein facilitates the delivery of cholesterol to the inner mitochondrial membrane, the rate-limiting step in steroidogenesis. ACTH and LH pathway also includes tyrosine dephosphorylation processes. Indeed, our previous studies have demonstrated that both hormones increase protein tyrosine phosphatase (PTP) activity by a PKA-dependent mechanism and that the action of PTPs is required for the stimulation of steroid biosynthesis in adrenal and Leydig cells. In order to test the putative relationship between PTP activity and StAR protein induction in adrenocortical cells, in the present study we evaluated steroid production and StAR protein level in Y1 adrenocortical cells under PTP inhibition. Phenylarsine oxide (PAO), a powerful cell permeable PTP inhibitor, reduced ACTH-stimulated steroidogenesis in a concentration-dependent fashion. A concentration of 2.5 microM of this compound inhibited steroid synthesis in a 56% (ACTH = 318 +/- 30, ACTH + PAO = 145 +/- 18 ng progesterone/mL, P < 0.001) and also abrogated StAR protein induction. Phenylarsine oxide reduced the protein level after 60 min and this effect still remained at 120 min. A second PTP inhibitor, benzyl phosphonic acid, acting by a different mechanism, reproduced PAO effects on both steroidogenesis and StAR protein. Taken together, these results indicate that PTP activity participates in StAR protein induction and led us to attribute to the PKA-mediated PTP activation in steroidogenic systems a functional role, as mediator of StAR protein induction.

Human umbilical vein: involvement of cyclooxygenase-2 pathway in bradykinin B1 receptor-sensitized responses

In isolated human umbilical vein (HUV), the contractile response to des-Arg9-bradykinin (des-Arg9-BK), selective BK B1 receptor agonist, increases as a function of the incubation time. Here, we evaluated whether cyclooxygenase (COX) pathway is involved in BK B1-sensitized response obtained in 5-h incubated HUV rings. The effect of different concentrations of indomethacin, sodium salicylate, ibuprofen, meloxicam, lysine clonixinate or NS-398 administrated 30 min before concentration-response curves (CRC) was studied. All treatments produced a significant rightward shift of the CRC to des-Arg9-BK in a concentration-dependent manner, which provides pharmacological evidence that COX pathway is involved in the BK B1 responses. Moreover, in this tissue, the NS-398 pKb (5.2) observed suggests that COX-2 pathway is the most relevant. The strong correlation between published pIC50 for COX-2 and the NSAIDs' pKbs estimated further supports the hypothesis that COX-2 metabolites are involved in BK B1 receptor-mediated responses. In other rings, indomethacin (30, 100 micromol/l) or NS-398 (10, 30 micromol/l) produced a significant rightward shift of the CRC to BK, selective BK B2 agonist, and its pKbs were similar to the values to inhibit BK B1 receptor responses, suggesting that COX-2 pathway also is involved in BK B2 receptor responses. Western blot analysis shows that COX-1 and COX-2 isoenzymes are present before and after 5-h in vitro incubation and apparently COX-2 does not suffer additional induction.

LH/chorionic gonadotropin signaling pathway involves protein tyrosine phosphatase activity downstream of protein kinase A activation: evidence of an obligatory step in steroid production by Leydig cells

Our recent reports indicate that protein tyrosine phosphorylation is an obligatory component of the mechanism of action of ACTH in its stimulatory action of corticosteroid production in adrenal zona fasciculata (ZF). The role of protein tyrosine phosphatase (PTP) activity in the regulation of steroidogenesis by LH/chorionic gonadotropin (CG) was tested using cell-permeable PTP inhibitors. Thus, PTP inhibition blocks LH- and 8-bromo-cAMP-stimulated testosterone production by Leydig cells without affecting 22(R)OH-cholesterol-supported steroidogenesis, similar results to those obtained in the adrenal ZF/ACTH system, leading us to propose that PTP action is an obligatory and common step in the cascade triggered by both hormones. Then, we continued the study testing whether LH modulates PTP activity in MA-10 cells, a Leydig cell line. In this regard, we observed by an in-gel PTP assay two PTPs of 110 and 50 kDa that are activated by hormone and 8-bromo-cAMP activation of the cells. Moreover, there is a transient increase by the second messenger in total PTP activity that correlates with the higher activity displayed by the 110 and 50 kDa proteins in the in-gel assay. In accordance with these results, analysis of tyrosine phosphorylated proteins showed the LH-induced dephosphorylation of proteins of 120, 68 and 50 kDa. The results of this study indicate that PTPs play an important role in the regulation of Leydig cell functions and that there exists a cross talk between serine/threonine phosphorylation and tyrosine dephosphorylation mediated by hormone-activated cAMP-dependent protein kinase and PTPs. These results are the first evidence of PTP having a role in LH/CG-stimulated steroidogenesis.

An ACTH-activated protein tyrosine phosphatase (PTP) is modulated by PKA-mediated phosphorylation

In adrenal cortex, ACTH regulation of steroidogenesis depends on PKA-dependent serine/threonine phosphorylation and also on the activity of protein tyrosine phosphatases (PTPs). In addition, ACTH increases total PTPs involving at least three soluble PTPs (50, 82 and 115 kDa). Serine/threonine phosphorylation of these enzymes themselves could be a regulatory mechanism of their activity since the increase of total PTP activity is dependent on PKA-activation. In this report we analyzed the effect of in vitro phospho-dephosphorylation processes on the activity displayed by the ACTH-activated PTP of 115 kDa. Using an in-gel PTP assay we demonstrate that dephosphorylation catalyzed by potato acid phosphatase (PAP) reduces the activity of the 115 kDa PTP present in ZF from ACTH-treated animals and PKA-mediated phosphorylation reverses this effect.

Regulation of arachidonic acid release in steroidogenesis: role of a new acyl-CoA thioestrase (ARTISt)

It has been well established that arachidonic acid (AA) and its metabolism to leukotrienes plays an obligatory role in steroid production. The release of AA is regulated by hormone stimulation and protein phosphorylation. We have cloned a cDNA of a phosphoprotein with a molecular mass of 43 kDa (p43), purified from the cytosol of stimulated adrenal glands. This protein acts as intermediary in the stimulation of steroid synthesis through AA release, and has been found to be a member of a recently described acyl-CoA thioesterase family. In view of the mandatory role of this protein in the activation of AA-mediated steroidogenesis, the term Arachidonic acid-Related Thioesterase Involved in Steroidogenesis (ARTISt), is proposed for p43. The present study describes the production of the recombinant protein by cDNA expression in Escherichia coli and its functional characterization. Recombinant acyl-CoA thioesterase was capable to release AA from the respective acyl-CoA, and this activity was affected by well-recognized inhibitors of AA release and metabolism: 4-bromophenacyl bromide (BPB) and nordihydroguariaretic acid (NDGA). In addition, the inhibition of acyl-CoA thioesterase activity by NDGA correlates with the inhibition of steroid synthesis produced by this compound in adrenal cortex cells. Moreover, the recombinant protein was phosphorylated in vitro by PKA. These results provide the first evidence linking acyl-CoA thioesterases with the regulation of steroidogenesis, and support a regulatory role for acyl-CoA thioesterases in steroidogenic tissues, suggesting an alternative pathway for AA release in signal transduction.

Cerebellar morphological alterations in rats induced by prenatal ozone exposure

The present study analyzes the morphological aspects of the cerebellum of rats with prenatal exposure to ozone. A double blind histological and planimetric analysis was performed studying sagittal sections of the anterior cerebellar lobe at postnatal days 0, 12 and 60. Ozone exposed rats showed cerebellar necrotic signs at age 0, diminished area of the molecular layer with Purkinje cells with pale nucleoli and perinucleolar bodies at age 12, and Purkinje cells showing nuclei with unusual clumps of chromatin in the periphery at age 60. We conclude that exposure to high concentrations of ozone during gestation induces permanent cerebellar damage in rats.

Corticotropin increases protein tyrosine phosphatase activity by a cAMP-dependent mechanism in rat adrenal gland

Corticotropin signal transduction pathway involves serine/threonine protein phosphorylation. Recent reports suggest that protein tyrosine dephosphorylation may also be an integral component of that pathway. The present study was performed to investigate the role played by protein tyrosine phosphatases (PTPs) on acute response to corticotropin and the hypothetical regulation of PTPs by this hormone. We have used two powerful cell permeant PTP inhibitors, phenylarsine oxide (PAO) and pervanadate (PV), in order to examine the relevance of PTP activity on hormone-stimulated and 8-bromo-adenosine 3',5'-phosphate (8Br-cAMP is a permeant analogue of adenosine 3',5'-phosphate)-stimulated steroidogenesis in adrenal zona fasciculata (ZF) cells. In both cases, PAO and PV inhibited the steroid production in a dose-dependent fashion, and had no effect on steroidogenesis supported by a permeant analogue of cholesterol. The effect of hormonal stimulation on PTP activity was analyzed in rat adrenal ZF. In vivo corticotropin treatment reduced phosphotyrosine content in endogenous proteins and produced a transient increase of PTP activity in the cytosolic fraction, reaching a maximum (twofold) after 15 min. Incubation of adrenal ZF with 8Br-cAMP also produced PTP activation, suggesting that it can be mediated by cAMP-dependent protein kinase (PKA)-dependent phosphorylation. Detection of PTP activity in an in-gel assay showed three corticotropin-stimulated soluble PTPs with molecular masses of 115, 80 and 50 kDa. In summary, we report for the first time a hormone-dependent PTP activation in a steroidogenic tissue and provide evidence that PTP activity plays an important role in corticotropin signal pathway, acting downstream of PKA activation and upstream of cholesterol transport across the mitochondrial membrane.

[Pulmonary atresia with intact interventricular septum. Report of a case diagnosed by fetal echocardiography]

Pulmonary atresia with intact ventricular septum (PA/IVS) is a rare cardiac congenital malformation involving the right ventricle (RV) in which the communication through pulmonary valve, is absent. A case of a congenital heart disease (CHD) consisting of pulmonary atresia with intact ventricular septum (PA/IVS) and small right ventricle (RV) or type I of Greenwold, coming from a twin pregnancy in which the other was an inutero dead fetus, is reported. Although the case was referred after the death of one of the fetuses, the prenatal diagnosis was made by the use of echocardiographic studies and confirmed by anatomopathology of the still-born fetus with the CHD. The very useful echocardiographic prenatal diagnosis and surgical therapeutical options are emphasized and discussed.

An adrenocorticotropin-regulated phosphoprotein intermediary in steroid synthesis is similar to an acyl-CoA thioesterase enzyme

We have previously reported the purification of a phosphoprotein (p43) intermediary in steroid synthesis from adrenal zona fasciculata [Paz C., Dada, L. A., Cornejo Maciel, M. F., Mele, P. G., Cymeryng, C. B., Neuman, I., Mendez, C. F., Finkielstein, C. V., Solano, A. R., Park, M., Fischer, W. H., Towbin, H., Scartazzini, R. & Podestá, E. J. (1994) Eur J. Biochem. 224, 709-716]. Here, we describe the cloning and sequencing of a cDNA encoding p43 as well as the hormonal regulation of the p43 transcript. The protein resulted homologous to a very recently described mitochondrial peroxisome-proliferator-induced very-long-chain acyl-CoA thioesterase (MTE-I). The deduced amino acid sequence of the protein shows consensus sites for phosphorylation by different protein kinases, and a lipase serine motif. Antibodies raised against a synthetic peptide that includes the lipase serine motif and against the N-terminal region of p43 block the action of the protein. The transcript of p43 was detected in ovary of pseudopregnant rats, rat adrenal zona fasciculata and glomerulosa, mouse Leydig tumor cell line (MA-10), rat brain and human placenta. Inhibition of adrenocorticotropin hormone (ACTH) release and steroid synthesis by dexamethasone produced a dose-dependent decrease in the abundance of the adrenal transcript. The transcript was induced by in vivo stimulation of the adrenals with ACTH. The effect had a rapid onset (5 min), reached maximal stimulation (62%) at 15 min, and returned to basal levels at 30 min. The effect of ACTH on the p43 transcript was inhibited by actinomycin D and enhanced by cycloheximide. Our results provide the first evidence linking acyl-CoA thioesterases with very-long-chain specificities, and a protein intermediary in steroid synthesis, thereby supporting a regulatory role for acyl-CoA thioesterases in steroidogenic tissues.

Phosphotyrosine protein phosphatases activation by ACTH in rat adrenal gland

The steady state level of most cellular phosphoproteins is dependent on the relative catalytic activities of intracellular protein kinases and phosphatases. In adrenal cortex, ACTH acts through PKA activation and Ser/Tre phosphorylation. Phosphatases involved in this pathway are not completely described, particularly the role of phosphotyrosine protein phosphatase (PTP) activity on ACTH action. We investigated potential changes in PTPs activity in adrenal gland upon in vivo and in vitro PKA activation. In vivo ACTH stimulates cytosolic PTP activity (2-fold). Similar effect is detected by in vitro stimulation. In accordance with the effects of ACTH on PTP activity, cell permeable PTP inhibitors block ACTH stimulation on adrenal zona fasciculata (ZF) cells: ACTH (1 nM) = 108.2 +/- 3.5 ng corticosterone/10(5) cells vs. ACTH + phenylarsine oxide (2 nM) = 60 +/- 4 (P < 0.001) and ACTH + pervanadate (10 mM) = 68 +/- 2 (P < 0.01). These results are reproduced when cells are stimulated with cAMP. The inhibition is not observed when steroidogenesis is supported by 22(R)OH cholesterol. We describe, for the first time, a hormonal regulation of PTP activity. According to the effect of PTP inhibitors on steroid production activated by ACTH we propose that PTP activation is a crucial event in hormone action in the steroidogenic pathway. We also propose that PTP activity is located after PKA activation and prior to cholesterol transport to the inner mitochondrial membrane.

Development of an experimental model of epilepsy in rats exposed to ozone

Paroxysmal activity has been reported in the olfactory bulb of rabbits chronically exposed to ozone (O3), postulating that this gas provokes alterations in the electrical activity of the central nervous system. The effects of 1 ppm of O3 inhaled daily for 1 or 3 h prior to each stimulation were studied using the kindling model of epilepsy. Results showed that O3 decreased the duration of the amygdaloid after-discharges during the development of kindling and shortened the latency to the onset of the first generalized seizure in rats exposed for 1 h to O3, while the group exposed for 3 h also decreased the after-discharge duration but delayed the appearance of seizures. Spread of seizure activity, defined as the latency to reach behavioral and electrographic signs of tonic clonic seizures was faster in the 1 h O3 exposed rats and slower in those exposed for 3 h. These findings demonstrate that O3 or its reaction products, such as free radicals, could affect the mechanisms involved in kindling course, such changes being dependent of the time of O3 exposure.

Some consequences of ozone exposure on health

The reaction of ozone with polyunsaturated fatty acids from the surfactant factor and pulmonary epithelial cells produces different reaction products which can cross the alveolar-capillary barrier and reach distant structures. Although only a few papers claim extrapulmonary changes in animals exposed to this gas, some neurological deficits, such as complaints of fatigue, lethargy, headache in humans, as well as significant disarrangements in the sleep pattern related to biochemical changes in the brain have been referred to in animals exposed to ozone. In the present review, the molecular configuration and the reaction of ozone at different lung levels are related to impairment at the respiratory and blood systems, in order to elucidate the mechanisms by which this gas or its reaction products, such as free radicals, prostaglandins and others can cross the alveolar-capillary and hemato-encephalic barriers, and to explain those neurological effects.

Ozone produces functional deficits in the rat visual pathway

The effects of ozone (O3) have been studied mainly in reference to the respiratory pathways, though some reports have shown that this gas produces noxious effects in brain. The aim of the present work was to study the O3 effects on the central nervous system, focusing on the visual pathway by means of visual evoked potentials technique recording in the visual cortex and the lateral geniculate nucleus of rats exposed to three different concentrations of O3 (0.75, 1.5 and 3.0 ppm). Our results showed that P1, N1 and P2 components were significantly delayed in the visual cortex and lateral geniculate nucleus in those rats exposed to 3.0 ppm of O3. Moreover, the N1 component in the visual cortex was also affected even under exposure to 1.5 ppm of O3. Results suggest that O3 exposure affects the conduction mechanisms and synaptic excitability of the visual pathway. It is known that inhalation of O3 produce a cascade of ozonation products capable of producing lipid peroxidation in the brain. Unevenness of some neurotransmitters has also been referred in animals exposed to this gas. Thus we consider that the delay found in the primary components of the visual evoked potentials could obey to a neurochemical disorder produced by O3 inhalation.

Involvement of arachidonic acid and the lipoxygenase pathway in mediating luteinizing hormone-induced testosterone synthesis in rat Leydig cells

Evidence has been introduced linking the lipoxygenase products and steroidogenesis in Leydig cells, thereby supporting that this pathway may be a common event in the hormonal control of steroid synthesis. On the other hand, it has also been reported that lipoxygenase products of arachidonic acid (AA) may not be involved in Leydig cells steroidogenesis. In this paper, we investigated the effects of PLA2 and lipoxygenase pathway inhibitors on steroidogenesis in rat testis Leydig cells. The effects of two structurally unrelated PLA2 inhibitors (4-bromophenacyl bromide (BPB) and quinacrine) were determined. BPB blocked the LH- and Bt2cAMP-stimulated testosterone production but had no effect on 22(4)-OH-cholesterol conversion to testosterone. Quinacrine caused a dose-dependent inhibition of LH- and Bt2cAMP-induced steroidogenesis. The effects of different lipoxygenase pathway inhibitors (nordihydroguaiaretic acid (NDGA), 5,8,11,14-eicosatetraynoic acid (ETYA), caffeic acid and esculetin) have also been determined. Both NDGA and ETYA inhibited LH- and Bt2cAMP-stimulated steroid synthesis in a dose-related manner. Furthermore caffeic acid and esculetin also blocked the LH-stimulated testosterone production. Moreover, exogenous AA induced a dose-dependent increase of testosterone secretion which was inhibited by NDGA. Our results strongly support the previous concept that the lipoxygenase pathway is involved in the mechanism of action of LH on testis Leydig cells.

Brain monoamine changes in rats after short periods of ozone exposure

We have shown in our laboratory that cat's and rat's sleep disturbances are produced by 24 h of ozone (O3) exposure, indicating that the central nervous system is affected by this gas. To demonstrate the probable changes in brain neurotransmitters, we evaluated the monoamine contents of the midbrain and striatum of rats exposed to 1 part per million O3 for 1 or 3 hours periods. The results were compared with rats exposed to fresh air and to those exposed to 3 hours of O3 followed by 1 or 3 hours of fresh air. We found a significant increase in dopamine (DA) and its metabolites noradrenaline (NA) and 3,4 dihydroxyphenylacetic acid (DOPAC), as well as an increase in the 5-hydroxyindolacetic acid (5-HIAA) contents of the striatum. There were no changes in homovanillic acid (HVA) and serotonin (5-HT) levels during O3 exposure. Additionally, an increase in DA, NA and 5-HIAA in the midbrain during O3 exposure was observed. Turnover analysis revealed that DA increased more than its metabolites in both the midbrain and striatum. However, the metabolite of 5-HT, i.e. 5-HIAA, increased more than its precursor, this reaching statistical significance only in the midbrain. These findings demonstrate that O3 or its reaction products affect the metabolism of major neurotransmitter systems as rapidly as after 1 h of exposition.

Characterization of the cDNA corresponding to a phosphoprotein (p43) intermediary in the action of ACTH

We have previously isolated and partially-sequenced a soluble phosphoprotein (p43) that acts as intermediary in the stimulation of steroid synthesis. In this report we have used synthetic peptides whose sequences match those obtained from p43 to generate antipeptide antibodies and show that these antibodies bind to purified p43 protein as determined by immunoblot analysis. The presence of p43 was detected by Western blot in both steroidogenic and non-steroidogenic tissues. One of the antibodies was also used to purify p43 on immunoaffinity chromatography columns. Proteins eluting from affinity columns produce a twelve-fold stimulation of progesterone synthesis. This effect was blocked by the use of an inhibitor of phospholipase A2. These results suggest the involvement of p43 in transducing the adrenocorticotropin signal to mitochondria in zona fasciculata cells. We also describe a partial cDNA clone with a predicted amino acid sequence that matches the sequences of the internal peptides of p43.

Cytosolic and mitochondrial proteins as possible targets of cycloheximide effect on adrenal steroidogenesis

It is well accepted that protein(s) with a short half-life are required in the pathway leading to steroid synthesis following stimulation by trophic hormones. A correlation between the disappearance of several proteins in different subcellular compartments and the inhibition of steroid synthesis produced by cycloheximide (CHx) has also been shown. In the present report we describe the effect of CHx in the stimulation of steroid synthesis using a cell-free assay. Mitochondrial progesterone (P4) production was studied by recombination of the different subcellular fractions of adrenal zona fasciculata and determined by radioimmunoassay. Soluble factors from ACTH-treated adrenals produced a four-fold stimulation of mitochondrial steroidogenesis (3.0 +/- 0.6 vs. 13.3 +/- 0.5 ng P4/tube for control and ACTH-treated adrenals respectively). Mitochondria obtained from CHx-ACTH-treated adrenals fail to respond to soluble ACTH-dependent factors. A permeable analogue of cholesterol (22(R)-OH cholesterol) could overcome the inhibition imposed by CHx, confirming the role of mitochondrial proteins in intramitochondrial cholesterol transport. The treatment of the adrenals with CHx 10 minutes before ACTH administration abolished also the stimulation induced by the cytosol on control mitochondria (2.6 +/- 0.5 vs. 13.0 +/- 1.0 ng P4/tube for CHx-ACTH-treated cytosol vs. ACTH-treated cytosol). Arachidonic acid (AA) added to CHx-ACTH-treated cytosol subdued this inhibition (10.3 +/- 1.2 ng P4/tube). CHx treatment had no effect on the stimulation by ACTH of the cAMP-dependent protein kinase. These results indicate the involvement of a cycloheximide-sensitive protein in the release of AA in adrenal steroidogenesis.

Site of action of proteinases in the activation of steroidogenesis in rat adrenal gland

We have investigated the effect of the proteinase inhibitors 1,10-phenantroline (OP) and phenylmethylsulfonyl fluoride (PMSF) on steroidogenesis in rat adrenal cortex. Both PMSF and OP inhibited adrenocorticotropin (ACTH)- and 8-Br cAMP-induced stimulation of corticosterone synthesis. On the contrary, arachidonic acid-induced stimulation of corticosterone synthesis was only slightly inhibited by PMSF and unchanged by OP. Intra- and extracellular cAMP levels were determined by radioimmunoassay. While PMSF did not affect neither the intra- nor the extracellular cAMP levels, OP decreased the intra- and extracellular levels of unstimulated as well as ACTH-stimulated cells. The site of action of the proteinase inhibitors was also studied by recombination of mitochondria with the different subcellular fractions in vitro. Addition of PMSF abolished the stimulation achieved by in vitro activation of cytosol by cAMP and PKA. On the other hand, OP completely inhibited the activation of mitochondria. Our results provide evidence for the involvement of proteinases in ACTH-induced stimulation of steroidogenesis in adrenal cortex both prior to the release of arachidonic acid and at the level of cholesterol transport from the outer to the inner mitochondrial membrane.

The effects of ozone exposure on the sleep-wake cycle and serotonin contents in the pons of the rat

Polysomnographic studies were done at hourly intervals during 0.00, 0.35, 0.75 and 1.50 ppm of ozone (O3) exposure. We found a significant decrease in paradoxical sleep after 2 h and an increase in slow wave sleep after 12 h at all concentrations of O3. High resolution liquid chromatography demonstrated an increase in 5-HT concentration in the rat pons, in a roughly stepwise fashion as the O3 concentration increased. We propose that reaction products derived from O3 exposure, such as prostaglandins, could be affecting those physiological and biochemical mechanisms critical for the generation and maintenance of the sleep-wake cycle.

ACTH-dependent proteolytic activity of a novel phosphoprotein (p43) intermediary in the activation of phospholipase A2 and steroidogenesis

Arachidonic acid (AA) and the lipooxygenase products have been shown to play an obligatory role in the mechanism of action of LH and ACTH, at a point after cAMP-dependent phosphorylation. We have demonstrated the presence of a phosphoprotein (p43) that responds to cAMP signals to induce steroid synthesis in adrenocortical tissue, an effect that is blocked by phospholipase A2 inhibitors. In this report we demonstrate that p43 exhibits autoproteolytic activity that is regulated by ACTH. Protein purified from ACTH-treated animals exhibited degradation in some of the isoforms resolved on two dimensional gel electrophoresis. Proteinase inhibitors (PMSF and 1,10 phenantroline) inhibited steroid synthesis induced by ACTH and 8-Br-cAMP in intact cells. Addition of exogenous AA reverted in part that inhibition. Here we present evidence for a hormone-regulated proteolytic activity of p43 and for the inhibition of steroidogenesis by proteinase inhibitors acting prior to the release of arachidonic acid.

Purification of a novel 43-kDa protein (p43) intermediary in the activation of steroidogenesis from rat adrenal gland

In previous reports we have demonstrated the presence of a soluble factor that responds to cAMP signals to induce steroid synthesis in adrenocortical tissue. Here, we describe the purification of this factor from adrenal zona fasciculata cells by using a five-step procedure that includes DEAE-cellulose, gel filtration, Mono Q HPLC and Superose HPLC, and elution of the protein from SDS/PAGE. This procedure results in the purification to homogeneity of a protein of 43-kDa that retains the capacity to stimulate steroid synthesis in an in vitro recombination assay. This activity is inhibited by the use of phospholipase A2 inhibitors. Antipeptide antibodies against the N-terminal region recognize p43 as a double band on SDS/PAGE that resolves in different spots on two-dimensional gel electrophoresis. Adrenocorticotropin treatment of adrenal glands results in the appearance of multiple spots that migrated towards a lower pH compared to controls, suggesting the presence of phosphorylated and dephosphorylated forms of p43. Sequencing of the N-terminal region and internal peptides reveals no significant similarities with other proteins, suggesting that p43 is a novel protein. We conclude from our data that the isolated protein (p43) is a novel, soluble protein that acts as intermediary in adrenocorticotropin-induced stimulation of arachidonic acid release and steroid synthesis.

Sleep alterations and brain regional changes of serotonin and its metabolite in rats exposed to ozone

Sleep alterations and brain regional changes of serotonin were studied in rats exposed to 1.5 ppm of ozone (O3). Results showed a significant decrease in the time spent in wakefulness (W) and paradoxical sleep (PS) and a significant increase in the time spent in slow wave sleep (SWS). Neurochemical analysis showed a significant increase in the metabolism of serotonin in medulla oblongata, pons and midbrain, while both serotonin and its metabolite were reduced in hypothalamus. Although other neurotransmitters could be affected by O3 exposure, the sleep disorders observed in the present work may be related to alterations in the metabolism of serotonin produced by the exposure to O3.

Effects of ozone exposure during pregnancy on ontogeny of sleep in rats

Few studies regarding the effects of ozone exposure in the central nervous system (CNS), during the early stages of development have been reported. The study of sleep on newborn rats represents a model to understand the effects of this gas on the CNS. We studied the sleep organization in rats whose mothers were exposed to 1 part per million (ppm) ozone during pregnancy. We found severe sleep disturbances such as a decrease in paradoxical sleep duration and inversion of the light-dark cycle or a circadian phase-shift of vigilance states. These results suggest that ozone exposure during pregnancy may affect the generating mechanisms of paradoxical sleep, and the regulation of circadian rhythms in rats.

Changes in the threshold of pentylenetetrazol-induced seizures in cats with a chronic granuloma in brain amygdala

A parenchymal brain granuloma is the final consequence of a localized inflammatory reaction against an infectious agent, particularly parasites. In humans, these lesions are frequent causes of epilepsy. We studied the pattern of seizures induced by pentylenetetrazol (PTZ) in cats with a chronic granuloma induced 1 year earlier by injection of silicates into the brain amygdala. Compared with controls, the seizure threshold to myoclonic seizures was significantly decreased in cats with granuloma, while the threshold for tonic-clonic seizures was not altered. Thus, the difference in PTZ doses between the initial and final components of the seizure became significantly enlarged (P < 0.001). Our results indicate that a granulomatous lesion in amygdala facilitates the generation and propagation of myoclonic seizures, whereas other components of PTZ-induced seizures are not affected.

Sleep-wake disorganization in cats exposed to ozone

The effects of the exposure to ozone in the central nervous system are unknown, as it is doubtful if ozone enters beyond the respiratory tract. However, ozone exposure impairs human performance and induces subjective complaints such as fatigue, lethargy and headache. We studied electrographic aspects of sleep-wake organization in cats, and found that paradoxical sleep was promptly reduced during ozone exposure, followed by a dose-related increase of slow-wave sleep. These findings suggest that high concentrations of ozone or its reaction products induce striking changes in sleep patterns.