The complex roles of neurosteroids in depression and anxiety disorders

The role of neurosteroids in neuropsychiatric disorders has been thoroughly investigated in many research studies that have stressed their significant pathophysiological function in neuropsychiatry. In this review, we will focus mainly on the steroids active on the GABA(A) receptors studied in anxiety and depression. The aim is to discuss the controversial results reported in research on anxiety and depressive disorders. We suggest the combined use of biological parameters linked to psychopathological dimensions to make more homogeneous diagnoses and to develop more precise therapies for the treatment of depression and anxiety disorders. We discuss the role of neurosteroids in the pathophysiology and therapy of anxiety and depression. Finally, we consider the possibility of using quantification of mRNA expression of steroidogenic enzymes from peripheral sources in neuropsychiatry.     

Gamete cryopreservation in the domestic cat

Cryopreservation of gametes is an important tool for the improvement of assisted reproductive technologies. In-depth studies of spermatozoon and oocyte characteristics are required in order to define efficient protocols for the maintenance of viability, including fertilizing and developmental ability, of gametes after thawing. In the domestic cat, semen cryopreservation techniques still produce variable results, the cryopreservation of oocytes is at an experimental level and there have been only a few attempts at cryopreserving gonadal tissue. However, each procedure has generated promising results and has important implications, both for improving reproductive performance of valuable breeds of domestic cats and for conservation of biodiversity in endangered felids by reclamation of valuable male and female germplasm.     

Culture strategies for maturation of carnivore oocytes

In vitro maturation (IVM) of carnivore oocytes is still under investigation. It is well known that oocytes must accomplish nuclear and cytoplasmic maturation to acquire developmental competence. However, little is known about mechanisms regulating these events in carnivore oocytes. Consequently, IVM rates are still lower than those obtained in other species. To improve results in carnivores, two strategies have to be investigated: one finalized towards preserving in vitro functional integrity and potentiality to accomplish complete maturation of cumulus-oocyte complexes (COCs), the other finalized towards providing culture conditions adequate for sustaining complete maturation of these oocytes. Thus, modifications of the culture environment during IVM, by addition of substances that stimulate endogenous systems of cell defence and modulate the intracellular levels of regulatory molecules, or by use of sequentially different culture systems, are interesting strategies for enhancing viability and competence in terms of complete maturation of carnivore oocytes. This review is focused on recent advances in the study of these aspects developed in feline and/or canine oocytes.     

The RhoA-associated protein Citron-N controls dendritic spine maintenance by interacting with spine-associated Golgi compartments

Dendritic spines are highly dynamic protuberances that are thought to be crucial for learning and memory. Although it is well known that actin filaments and membrane dynamics regulate spine plasticity, how these two events are linked locally is less clear. Here, we provide evidence that Citron-N (CIT-N), a binding partner of the small GTPase RhoA, is associated with the actin filaments and Golgi compartments of dendritic spines. We also show that CIT-N is required for recruiting F-actin and Golgi membranes at spines of in vitro-grown neurons. Studies in knockout mice show that this protein is essential for the maturation of dendritic spines. We suggest that CIT-N might function as a scaffold protein in spine organization through its ability to bind to Golgi membranes and by affecting actin remodelling.     

Mitochondrial permeability transition involves dissociation of F1FO ATP synthase dimers and C‐ring conformation

The impact of the mitochondrial permeability transition (MPT) on cellular physiology is well characterized. In contrast, the composition and mode of action of the permeability transition pore complex (PTPC), the supramolecular entity that initiates MPT, remain to be elucidated. Specifically, the precise contribution of the mitochondrial F₁F_O ATP synthase (or subunits thereof) to MPT is a matter of debate. We demonstrate that F₁F_O ATP synthase dimers dissociate as the PTPC opens upon MPT induction. Stabilizing F₁F_O ATP synthase dimers by genetic approaches inhibits PTPC opening and MPT. Specific mutations in the F₁F_O ATP synthase c subunit that alter C‐ring conformation sensitize cells to MPT induction, which can be reverted by stabilizing F₁F_O ATP synthase dimers. Destabilizing F₁F_O ATP synthase dimers fails to trigger PTPC opening in the presence of mutants of the c subunit that inhibit MPT. The current study does not provide direct evidence that the C‐ring is the long‐sought pore‐forming subunit of the PTPC, but reveals that PTPC opening requires the dissociation of F₁F_O ATP synthase dimers and involves the C‐ring.     

Effect of lacidipine on ischaemic and reperfused isolated rabbit hearts

Lacidipine is a new developed dihydropyridine calcium-antagonist, showing a slow onset and long lasting-selective activity.To assess whether the administration of lacidipine protects the myocardium in a dose-dependent manner against ischaemia and reperfusion, isolated rabbit heart were infused with three different concentrations of lacidipine: 10^–10; 10^–9; 10^–8 M. Diastolic and developed pressures were monitored; coronary effluent was collected and assayed for CPK activity and for noradrenaline concentration; mitochondria were harvested and assayed for respiratory activity, ATP production and calcium content and tissue concentration of ATP, creatine phosphate (CP) and calcium were determined. Occurrence of oxidative stress during ischaemia and reperfusion was also monitored in terms of tissue content and release of reduced (GSH) and oxidized (GSSG) glutatione. Treatment with lacidipine at 10^–10 and 10^–9 M had no effects on the hearts when perfused under aerobic condition, whilst the higher dose reduced developed pressure of 36%. The ischaemic-induced deterioration of mitochondrial function was attenuated. On reperfusion treated hearts recovered better than the untreated hearts with respect to left ventricular performance, replenishment of ATP and CP stores and mitochondrial function. The reperfusion-induced tissue and mitochondrial calcium overload, release of CPK and of noradrenaline and oxidative stress were also significantly reduced. The effects of lacidipine were dose-dependent. The lower concentration (10^–10 M) failed to modify ischaemic and reperfusion damage. The dose of 10^–9 M was cardioprotective, but the best effect was found at 10^–8 M.It is concluded that lacidipine infusion provides a dose dependent protection of the heart against ischaemia and reperfusion. Because this protection occurred also at 10^–9 M, in the absence of negative inotropic effect during normoxia and of a coronary dilatory effect during ischaemia, it cannot be attributed to an energy sparing effect or to improvement of oxygen delivery. From our data we can envisage two other major mechanism:-1) membrane protection-2) reduction of oxygen toxicity. The ATP sparing effect occurring at 10^–8 M is likely to be responsable for the further protection.     

Are RB proteins a potential substrate of Pin1 in the regulation of the cell cycle?

RB family members are post-transductionally regulated proteins and phosphorylation at Ser/Thr residues leads to their gradual inactivation. Cyclin/cdk complexes are mainly responsible for the regulation of these pocket proteins, which is crucial for release of E2F factor. Despite the fact that E2F release is a phosphorylation-dependent process, it is still not evident how phosphorylation physically determines the shift from the active to the inactive feature of RB molecules. We would like to put forward the hypothesis that Pin1 is involved in RB proteins phosphorylation and E2F release, suggesting an additional post-translational level of control on this family of molecules.