mPer1 and mPer2 mutant mice show regular spatial and contextual learning in standardized tests for hippocampus-dependent learning.

Learning and memory, like most physiological processes, seem to be under the control of circadian rhythm. The recently cloned mPer1 and mPer2 genes play an important role in the regulation of the circadian rhythm. In this study, we tested mPer1 and mPer2 mutant mice in two different learning and memory paradigms, a water-maze place navigation task and contextual fear conditioning. In both learning tests, the hippocampus is critically involved. None of these learning types were affected by the mutations, suggesting that mPer1 and mPer2 do not play a major role in the regulation of hippocampus-dependent learning and memory.

Olfactory bulbectomy in mice induces alterations in exploratory behavior.

The olfactory bulbectomy syndrome is thought to represent a rodent model for psychomotor agitated depression. While this model has been extensively characterized in rats, fewer studies have been conducted with mice. Therefore, the present study aimed at extending the characterization of the OBX-induced behavioral syndrome in mice, using tests like open field, novel object exploration, novel cage and T-maze learning. OBX mice exhibited hyperactivity in a brightly illuminated open field, and also in a novel home cage as well as in the T-maze. Furthermore, OBX mice demonstrated increased exploratory behavior in the novel object test and in the T-maze. The complex alterations described here with respect to locomotion and exploration are robust and can be achieved by relatively simple test procedures. The extended behavioral characterization of the murine OBX model may contribute in particular to the increasing need to test transgenic mice for the presence of depression-like behaviors.

Implication of corticosteroid receptors in the regulation of hippocampal structural plasticity.

The dentate gyrus is one of the few areas of the adult brain that continues to produce neurons and to express the embryonic polysialylated isoforms of neuronal cell adhesion molecules (PSA-NCAM). The stress hormone corticosterone exerts a complex modulation on neurogenesis and PSA-NCAM, and previous studies have shown that mature granule cells require corticosterone for their survival. Thus, the aim of our work was to investigate the respective role of the different corticosteroid receptors on these three parameters in adrenalectomized rats. It was found that treatment with a low dose of the mineralocorticoid receptor agonist, aldosterone, prevents only the adrenalectomy-induced increase in cell death. Treatment with a higher dose of aldosterone normalized cell proliferation whereas PSA-NCAM expression was normalized only by treatment with the glucocorticoid receptor agonist, RU 28362. It is concluded that stimulation of the mineralocorticoid receptor is sufficient to mediate the effects of corticosterone on neurogenesis and to protect mature cells from cell death whereas stimulation of the glucocorticoid receptor is necessary to modulate PSA-NCAM expression.

Differential involvement of the sigma(1) (sigma(1)) receptor in the anti-amnesic effect of neuroactive steroids, as demonstrated using an in vivo antisense strategy in the mouse.

1. The sigma(1) (sigma(1)) receptor cDNA was cloned in several animal species. Molecular tools are now available to identify its endogenous effectors, such as neuroactive steroids, and to establish its precise physiological role. In particular, the sigma(1) receptor is involved in memory processes, as observed in pharmacological and pathological rodent models of amnesia. 2. In order to establish the involvement of sigma(1) receptors in memory, a 16-mer oligodeoxynucleotide antisense to the sigma(1) receptor cDNA (aODN), and its mismatched control (mODN) were prepared and centrally administered into the mouse brain. The anti-amnesic effects induced by the selective sigma(1) agonist PRE-084 and the steroid dehydroepiandrosterone (DHEA) sulphate or pregnenolone sulphate were examined in ODN-treated animals. 3. The aODN treatment failed to affect the dissociation constant (K(d)) but significantly decreased the number of sigma(1) sites (B(max)) labelled with [(3)H]-(+)-SKF-10,047 in the hippocampus and cortex. In these structures, the in vivo binding levels were also diminished, according to the dose and number of injections, as compared with control animals injected with saline or mODN. 4. Cannulation and injections failed to affect the open-field behaviour of the animals. However, the anti-amnesic effects of PRE-084 and DHEA sulphate against the dizocilpine-induced impairments were blocked after aODN treatment in the short- and long-term memory tests. The anti-amnesic effects of pregnenolone sulphate remained unchanged. 5. These observations bring a molecular basis to the modulatory role of sigma(1) receptors in memory, and reveal that the anti-amnesic action of neuroactive steroids may not similarly involve an interaction with sigma(1) receptors.

The interaction between neuroactive steroids and the sigma1 receptor function: behavioral consequences and therapeutic opportunities.

Steroids, synthesized in peripheral glands or centrally in the brain--the latter being named neurosteroids--exert an important role as modulators of the neuronal activity by interacting with different receptors or ion channels. In addition to the modulation of GABA(A), NMDA or cholinergic receptors, neuroactive steroids interact with an atypical intracellular receptor, the sigma(1) protein. This receptor has been cloned in several species, and highly selective synthetic ligands are available. At the cellular level, sigma1 agonists modulate intracellular calcium mobilization and extracellular calcium influx, NMDA-mediated responses, acetylcholine release, and alter monoaminergic systems. At the behavioral level, the sigma1 receptor is involved in learning and memory processes, the response to stress, depression, neuroprotection and pharmacodependence. Pregnenolone, dehydroepiandrosterone, and their sulfate esters behave as sigma1 agonists, while progesterone is a potent antagonist. This review will detail the physiopathological consequences of these interactions, focusing on recent results on memory and depression. The therapeutical interest of selective sigma1 receptor agonists in alleviating aging-related cognitive deficits will be discussed.

The antidepressant-like effect induced by sigma(1)-receptor agonists and neuroactive steroids in mice submitted to the forced swimming test.

The interaction of neuroactive steroids with the sigma(1)-receptor was investigated in Swiss mice submitted to the forced swimming test. The sigma(1)-agonists igmesine and (+)-SKF-10,047 and the steroid dehydroepiandrosterone sulfate (DHEAS) showed some antidepressant-like activity by shortening the immobility time, these effects being blocked by the sigma(1)-antagonist BD1047 or progesterone. The sigma(1)-agonist PRE-084 or pregnenolone sulfate failed to affect the immobility time. In adrenalectomized/castrated (AdX/CX) mice, the effects of igmesine and DHEAS were significantly potentiated, and PRE-084 or pregnenolone sulfate induced significant decreases of immobility time. The augmented effects in AdX/CX were fully blocked by BD1047. The effects of the classical antidepressants, desipramine or fluoxetine, were unchanged in AdX/CX mice. The effect of stress on the sigma(1)-receptor binding and neurosteroid levels was then examined in different brain structures, in terms of in vivo (+)-[(3)H]SKF-10,047 binding to sigma(1)-sites and neurosteroids levels. In the hippocampus, but not in the cortex or cerebellum, inhibition of in vivo (+)-[(3)H]SKF-10,047 binding was measured in parallel to the extent of progesterone levels according to the endocrine conditions. These data confirmed the antidepressant ability of sigma(1)-receptor agonists and revealed that the endogenous steroidal levels tonically interfere with the efficacy of the sigma(1)-system. It was observed that local modifications in progesterone levels are directly related to the changes of in vivo sigma(1)-binding. Such observations may be of major importance in view of the therapeutic use of selective sigma(1)-agonists in depression.

Differential effect of dehydroepiandrosterone and its steroid precursor pregnenolone against the behavioural deficits in CO-exposed mice.

The neuroactive steroids pregnenolone (3beta-hydroxy-5-pregnen-20-one) and dehydroepiandrosterone (DHEA, 3alpha-hydroxy-5-androstene-17-one) are negative allosteric modulators of the GABA(A) receptors and positive modulators of acetylcholine, NMDA and sigma(1) receptors. Pregnenolone was recently shown to potentiate the neuronal damage induced by excessive glutamate in cell culture models, whereas dehydroepiandrosterone was reported to present some neuroprotective activity. The in vivo relevance of these effects was investigated in mice submitted to an hypoxic insult, the repeated exposure to carbon monoxide (CO) gas, a model that leads to neurodegeneration in the CA(1) hippocampal area and learning deficits. Recording spontaneous alternation behaviour in the Y-maze assessed short-term memory and long-term memory was examined using a passive avoidance task. After exposure to CO, mice showed a progressive deterioration of their learning ability, reaching significance after 3 days and being maximal after 7 days. Pregnenolone administered before CO significantly facilitated the hypoxia-related deficits, which could be measured 1 day after CO and appeared maximal after 3 days. Dizocilpine blocked the deficits in vehicle- and pregnenolone-treated CO-exposed animals, showing that pregnenolone selectively facilitated the NMDA receptor-dependent excitotoxicity. Dehydroepiandrosterone blocked the appearance of the CO-induced deficits, even after 7 days. Interestingly, the sigma(1) receptor antagonist N, N-dipropyl-2-(4-methoxy-3-(2-phenylethoxy)phenyl)ethylamine (NE-100) failed to affect the dehydroepiandrosterone-induced protection, showing the lack of involvement of sigma(1) receptors. Cresyl violet-stained sections of the mouse hippocampal formation showed that the neurodegeneration observed in the CA(1) area after exposure to CO was augmented by pregnenolone and blocked by dehydroepiandrosterone. These results show that pregnenolone and dehydroepiandrosterone, although being similarly involved in modulating the excitatory/inhibitory balance in the brain, do not equally affect the extent of excitotoxic insults.

Neuroactive neurosteroids as endogenous effectors for the sigma1 (sigma1) receptor: pharmacological evidence and therapeutic opportunities.

Neuroactive neurosteroids, including progesterone, allopregnanolone, pregnenolone and dehydroepiandrosterone, represent steroid hormones synthesized de novo in the brain and acting locally on nervous cells. Neurosteroids modulate several neurotransmitter systems such as gamma-aminobutyric acid type A (GABA(A)), N-methyl-D-aspartate (NMDA) and acetylcholine receptors. As physiologic consequences, they are involved in neuronal plasticity, learning and memory processes, aggression and epilepsy, and they modulate the responses to stress, anxiety and depression. The sigma1-receptor protein was recently purified and its cDNA was cloned in several species. The amino-acid sequences are structurally unrelated to known mammalian proteins, but shared homology with a fungal sterol C8-C7 isomerase. The sigma1-receptor ligands exert a potent neuromodulation on excitatory neurotransmitter systems, including the glutamate and cholinergic systems. Consequently, selective sigma1 agonists show neuroprotective properties and beneficial effects in memory processes, stress and depression. The evidence of a direct interaction between neurosteroids and sigma1 receptors was first suggested by the ability of several steroids to inhibit the binding of sigma1-receptor radioligands in vitro and in vivo. A crossed pharmacology between neurosteroids and sigma1-receptor ligands was described in several physiological tests and behavioral responses. This review will detail the recent evidence for a common mechanism of action between neurosteroids and sigma1-receptor ligands and focus on the potential therapeutic interests of such interaction in the physiopathology of learning and memory impairments, stress, depression and neuroprotection.

The modulation by neurosteroids of the scopolamine-induced learning impairment in mice involves an interaction with sigma1 (sigma1) receptors.

Neurosteroids have been reported to modulate learning and memory processes in aged animals and in pharmacological models of amnesia. We report here the effects of dehydroepiandrosterone sulfate (DHEAS), pregnenolone sulfate (PREGS), and progesterone (PROG) on the learning impairment induced in mice by the muscarinic acetylcholine receptor antagonist, scopolamine. Spatial working memory was examined using the spontaneous alternation behavior in a Y-maze and long-term memory using place learning in a rectangular water-maze adapted for mice. Both DHEAS and PREGS (5-20 mg/kg, s.c.) prevented dose-dependently and significantly the scopolamine (2 mg/kg, s.c.)-induced alternation deficits. PROG (2-20 mg/kg, s.c.) failed to affect the scopolamine-induced deficits, but blocked, at 20 mg/kg, the beneficial effects induced by DHEAS or PREGS. In the water-maze, DHEAS (20 mg/kg) attenuated significantly the scopolamine-induced deficits, as observed during the acquisition sessions or the retention test. PROG (2, 20 mg/kg) did not affect the control or scopolamine-treated group performances, but blocked the ameliorating effect of DHEAS. Furthermore, in both tests, the selective sigma1 (sigma1) receptor antagonist NE-100 (1 mg/kg, i.p.) failed to affect the behaviors showed by the control or scopolamine-treated groups, but it blocked the ameliorating effects induced by DHEAS or PREGS. These results confirm the modulating role of neurosteroids in learning and memory processes and demonstrate that their modulation of the cholinergic systems involves an interaction with sigma1 receptors.

[Radiologic assessment in lung volume reduction surgery in emphysema]. / Valutazione radiologica nell'intervento di riduzione del volume polmonare per enfisema.

Aim of this work is to present and discuss the radiologic protocol we have developed for the preoperative assessment of patients with severe pulmonary emphysema candidate to lung volume reduction surgery (LVRS). The operation aims at improving respiratory mechanics and reducing small airway obstruction by removing variable amounts of emphysematous parenchyma. January to September, 1996, twelve patients were submitted to LVRS. Before surgery all patients were examined with standard chest radiographs during maximal inspiration and expiration, chest Computed Tomography (CT), High Resolution Computed Tomography (HRCT) and air trapping quantitation on HRCT scans. Diaphragm and chest wall excursions, patterns, site and distribution of emphysema, as well as heterogeneity (i.e., the uneven distribution of emphysematous and normal parenchyma) were investigated. Air trapping was quantitated with a dedicated software. Postoperative studies were carried out 2 months later in six patients and included: maximal inspiratory and expiratory chest radiographs and air trapping assessment on 3 standardized HRCT scans. All parameters considered improved in every patient. Radiologic studies proved to be of crucial importance for patient selection and LVRS planning. Despite our limited number of patients, the diagnostic protocol adopted in our Hospital appears a valuable tool for both pre- and post-operative assessment of the patients candidate to LVRS.

[Preoperative role of computerized tomography in videothoracoscopic lung surgery]. / Ruolo preoperatorio della Tomografia Computerizzata nella chirurgia polmonare videotoracoscopica.

Video-assisted thoracic surgery (VATS) is used in a growing range of pulmonary and mediastinal conditions. By avoiding thoracotomy, VATS is minimally invasive and allows shorter postoperative hospitalization. The advantages of video-assisted thoracoscopic techniques are obvious in the patients with severe cardiorespiratory failure. We investigated the role of CT before VATS. From September, 1991, to January, 1994, two hundred and eight patients were submitted to VATS: 80 pleurectomies, 63 lobectomies, 42 wedge resections, 11 bullectomies, 8 biopsies and 4 pneumonectomies were performed in patients with diffuse lung disease. All patients underwent conventional CT and an additional HRCT was performed in 164 patients. Bullae site, number, characteristics and size must be assessed. The possible relationship of bullae to impaired respiratory function must be studied. When nodules are present, their site, depth and relationship to fissures must be defined. With small and deep-seated nodules a thin snap-open mandrel device should be used for intraoperative detection. When lobectomies are contemplated, fissures must be accurately studied to assess their integrity and whether they completely separate the lobes. Fibrous adhesions can prevent pulmonary collapse; unfortunately, some of them cannot be detected by CT. Another limitation is the difficulty in assessing whether fissures are incomplete. To conclude, CT integrated with HRCT provides useful information for correct video-assisted thoracic surgical management.

[Color-Doppler in transrectal echography of the prostate. Preliminary results]. / Il color-Doppler nell'ecografia transrettale della prostata. Risultati preliminari.

The authors report their experience with the color Doppler study of the prostate in a series of 1,075 transrectal US exams performed September 1991 to June 1992. US-guided biopsy was performed in 82 patients; histopathology confirmed the diagnosis in 32 cases. Color-Doppler US provided accurate blood vessel mapping in the normal gland. As for benign prostate conditions, color-Doppler features definitely helped a diagnosis to be made, especially in nodular hyperplasia. Carcinomas usually exhibited marked and inhomogeneous increase in the vascularization of peri- and intralesional areas. This feature was especially valuable in isoechoic carcinomas where US is known to exhibit limitations. The authors suggest that the integration of clinical, laboratory and US with color-Doppler findings allows higher diagnostic accuracy.

[Role of echo-color Doppler in the diagnosis of breast diseases. Personal experience]. / Ruolo dell'eco-color-Doppler nella diagnostica della mammella. Esperienza personale.

The role of color-Doppler US was investigated in the diagnosis of solid focal breast lesions. The results obtained with this method over the last two years were reviewed. Seventy-two patients with solid breast lesions were considered: conventional US scans of the nodules were performed first and color-Doppler scans followed, to depict vascularization. In benign focal lesions color-Doppler US never demonstrated more than a single vascular pole afferent to the lesion. In 92.5% of histologically malignant lesions, color-Doppler US easily demonstrated two or more feeding vessels. The analysis of our series confirmed the presence of a typical vascular pattern related to breast carcinoma which is easy to depict by means of color-Doppler US: this new technique is therefore of great value in the differentiation of benign from malignant breast masses, especially in the cases where conventional US and mammography alone failed to yield unquestionable and final results.

[Preoperative localization and anchoring of pulmonary nodules under computed tomography guidance]. / Tecnica di localizzazione e ancoraggio preoperatorio dei noduli polmonari guidata con Tomografia Computerizzata.

Videoendoscopic thoracic surgery is often employed to remove peripheral lung nodules. Since manual palpation is excluded, the authors obviate the difficulty of intraoperative nodule localization by employing a thin snap open mandrel under CT to guidance localize, fix and anchor the nodule. Traction can be exerted on the device allowing for rapid nodule identification and facilitating wedge resection removal. This technical innovation, as yet applied only to a limited number of cases, widens the indications of videothoracoscopic surgery and appears complication-free.