Oxytocin in the medial preoptic area facilitates male sexual behavior in the rat

Oxytocin (OT) is a versatile neuropeptide that is involved in a variety of mammalian behaviors, and its role in reproductive function and behavior has been well established. The majority of pharmacological studies of the effects of OT on male sexual behavior have focused on the paraventricular nucleus (PVN), ventral tegmental area (VTA), hippocampus, and amygdala. Less attention has been given to the medial preoptic area (MPOA), a major integrative site for male sexual behavior. The present study investigated the effects of intra-MPOA administration of OT and (d(CH2)51, Tyr(Me)2, Thr4, Orn8, Tyr-NH29)-vasotocin, an OT antagonist (OTA), on copulation in the male rat. The relationship between OT receptor (OTR) binding levels in the MPOA and sexual efficiency was also explored. Microinjection of OT into the MPOA facilitated copulation in sexually experienced male rats, whereas similar injections of an OTA inhibited certain aspects of copulation but had no significant effect on locomotor activity in an open field. Contrary to expectation, sexually efficient males had lower levels of OTR binding in the rostral MPOA compared to inefficient animals. The present data suggest that OT activity in the MPOA is not necessary for the expression of male sexual behavior but is sufficient to facilitate copulatory behaviors and improve sexual efficiency in sexually experienced male rats. These data also suggest that OTR activity in the MPOA stimulates anogenital investigation, facilitates the initiation of copulation, and plays a role in the sensitization effect of the first ejaculation on subsequent ejaculations.     

Enhancing effects of 24-epibrassinolide and Putrescine on the antioxidant capacity and free radical scavenging activity of <Emphasis Type="Italic">Raphanus sativus</Emphasis> seedlings under Cu ion stress

The present investigation recorded significant restoration of seedling growth (root length, shoot length and fresh weight) upon application of 24-epibrassinolide (EBL) and putrescine (Put) to 7-day-old seedlings of Raphanus sativus L. cv. Pusa chetki grown under copper (Cu) ion stress. EBL and Put with/or without Cu ion treated seedlings showed increased titers of ascorbic acid, total phenols and proline when compared with Cu-stressed seedlings. Differential responses in the activities of guaiacol peroxidase (GPOX) and catalase (CAT) were noted for EBL and Put alone or with/or without Cu ion treatment. Decreased activities of glutathione reductase (GR) and superoxide dismutase (SOD) noted for EBL and Put alone were observed to enhance significantly when applied in combination with Cu ion solution. A remarkable decrease in malondialdehyde contents was observed in seedlings treated with EBL and Put alone and with/or without Cu ion stress. Enhanced free radical scavenging activities were also recorded for seedlings given EBL and Put alone or in combination over Cu ion stressed seedlings. Maximum DPPH activity was observed in seedlings treated with Put and EBL 10⁻⁹ M + Put. Significant enhancements in deoxyribose and reducing power activities were too recorded for Put, EBL and Put + 10⁻⁹ M EBL treatments. Improved seedling growth, antioxidant levels (ascorbic acid, total phenols and proline) and enzymic (GPOX, CAT, SOD and GR) activities and free radical scavenging capacities along with reduced membrane damage in seedlings given EBL and Put with/or without Cu stress suggests significant and positive interactions of EBL and Put in alleviating the Cu ion induced oxidative damage in radish seedlings.     

On the expansion of ribosomal proteins and RNAs in eukaryotes

While the ribosome constitution is similar in all biota, there is a considerable increase in size of both ribosomal proteins (RPs) and RNAs in eukaryotes as compared to archaea and bacteria. This is pronounced in the large (60S) ribosomal subunit (LSU). In addition to enlargement (apparently maximized already in lower eukarya), the RP changes include increases in fraction, segregation and clustering of basic residues, and decrease in hydrophobicity. The acidic fraction is lower in eukaryote as compared to prokaryote RPs. In all eukaryote groups tested, the LSU RPs have significantly higher content of basic residues and homobasic segments than the SSU RPs. The vertebrate LSU RPs have much higher sequestration of basic residues than those of bacteria, archaea and even of the lower eukarya. The basic clusters are highly aligned in the vertebrate, but less in the lower eukarya, and only within families in archaea and bacteria. Increase in the basicity of RPs, besides helping transport to the nucleus, should promote stability of the assembled ribosome as well as the association with translocons and other intracellular matrix proteins. The size and GC nucleotide bias of the expansion segments of large LSU rRNAs also culminate in the vertebrate, and should support ribosome association with the endoplasmic reticulum and other intracellular networks. However, the expansion and nucleotide bias of eukaryote LSU rRNAs do not clearly correlate with changes in ionic parameters of LSU ribosomal proteins.     

Characterizing the normal proteome of human ciliary body

Background

The ciliary body is the circumferential muscular tissue located just behind the iris in the anterior chamber of the eye. It plays a pivotal role in the production of aqueous humor, maintenance of the lens zonules and accommodation by changing the shape of the crystalline lens. The ciliary body is the major target of drugs against glaucoma as its inhibition leads to a drop in intraocular pressure. A molecular study of the ciliary body could provide a better understanding about the pathophysiological processes that occur in glaucoma. Thus far, no large-scale proteomic investigation has been reported for the human ciliary body.

Results

In this study, we have carried out an in-depth LC-MS/MS-based proteomic analysis of normal human ciliary body and have identified 2,815 proteins. We identified a number of proteins that were previously not described in the ciliary body including importin 5 (IPO5), atlastin-2 (ATL2), B-cell receptor associated protein 29 (BCAP29), basigin (BSG), calpain-1 (CAPN1), copine 6 (CPNE6), fibulin 1 (FBLN1) and galectin 1 (LGALS1). We compared the plasma proteome with the ciliary body proteome and found that the large majority of proteins in the ciliary body were also detectable in the plasma while 896 proteins were unique to the ciliary body. We also classified proteins using pathway enrichment analysis and found most of proteins associated with ubiquitin pathway, EIF2 signaling, glycolysis and gluconeogenesis.

Conclusions

More than 95% of the identified proteins have not been previously described in the ciliary body proteome. This is the largest catalogue of proteins reported thus far in the ciliary body that should provide new insights into our understanding of the factors involved in maintaining the secretion of aqueous humor. The identification of these proteins will aid in understanding various eye diseases of the anterior segment such as glaucoma and presbyopia.     

Targeted deletion of AIF decreases mitochondrial oxidative phosphorylation and protects from obesity and diabetes

Type-2 diabetes results from the development of insulin resistance and a concomitant impairment of insulin secretion. Recent studies place altered mitochondrial oxidative phosphorylation (OxPhos) as an underlying genetic element of insulin resistance. However, the causative or compensatory nature of these OxPhos changes has yet to be proven. Here, we show that muscle- and liver-specific AIF ablation in mice initiates a pattern of OxPhos deficiency closely mimicking that of human insulin resistance, and contrary to current expectations, results in increased glucose tolerance, reduced fat mass, and increased insulin sensitivity. These results are maintained upon high-fat feeding and in both genetic mosaic and ubiquitous OxPhos-deficient mutants. Importantly, the effects of AIF on glucose metabolism are acutely inducible and reversible. These findings establish that tissue-specific as well as global OxPhos defects in mice can counteract the development of insulin resistance, diabetes, and obesity.     

Thermodynamic analysis of acetylation-dependent Pb1 bromodomain-histone H3 interactions

An acetyl-histone peptide library was used to determine the thermodynamic parameters that define acetylation-dependent bromodomain-histone interactions. Bromodomains interact with histones by binding acetylated lysines. The bromodomain used in this study, BrD3, is derived from the polybromo-1 protein, which is a subunit of the PBAF chromatin remodeling complex. Steady-state fluorescence anisotropy was used to examine the variations in specificity and affinity that drive molecular recognition. Temperature and salt concentration dependence studies demonstrate that the hydrophobic effect is the primary driving force, consistent with lysine acetylation being required for binding. An electrostatic effect was observed in only two complexes where the acetyl-lysine was adjacent to an arginine. The large change in heat capacity determined for the specific complex suggests that the dehydrated BrD3-histone interface forms a tightly bound, high-affinity complex with the target site. These explorations into the thermodynamic driving forces that confer acetylation site-dependent BrD3-histone interactions improve our understanding of how individual bromodomains work in isolation. Furthermore, this work will permit the development of hypotheses regarding how the native Pb1, and the broader class of bromodomain proteins, directs multisubunit chromatin remodeling complexes to specific acetyl-nucleosome sites in vivo.     

Solvated Crystalline Forms of Nevirapine: Thermoanalytical and Spectroscopic Studies

The study is aimed at exploring the utility of thermoanalytical methods in the solid-state characterization of various crystalline forms of nevirapine. The different forms obtained by recrystallization of nevirapine from various solvents were identified using differential scanning calorimetry and thermogravimetric analysis (TGA). The appearance of desolvation peak accompanied by weight loss in TGA indicated the formation of solvates: hemi-ethanolate (Form I), hemi-acetonitrilate (Form II), hemi-chloroformate (Form III), hemi-THF solvate (Form IV), mixed hemi-ethanolate hemi-hydrate (Form V), and hemi-toluenate (Form VI). The higher desolvation temperatures of all the solvates except toluenate than their respective boiling point indicate tighter binding of solvent. Emphasis has been laid on the determination of heat capacity and heat of solution utilizing microreaction calorimeter to further distinguish the various forms. The enthalpy of solution (ΔH _sol), an indirect measure of the lattice energy of a solid, was well correlated with the crystallinity of all the solid forms obtained. The magnitude of ΔH _sol was found to be −14.14 kJ/mol for Form I and −2.83 kJ/mol for Form V in phosphate buffer of pH 2, exhibiting maximum ease of molecular release from the lattice in Form I. The heat capacity for solvation (ΔC _p) was found to be positive, providing information about the state of solvent molecules in the host lattice. The solubility and dissolution rate of the forms were also found to be in agreement with their enthalpy of solution. Form (I), being the most exothermic, was found to be the most soluble of all the forms.     

Inhibition of lindane-induced toxicity using alpha-lipoic acid and vitamin E in the brain of Mus musculus

In the present investigation, we have used adenosine triphosphatase (ATPase) activity as biochemical test of toxic action of lindane that was explained by lipid peroxidation model. Study was also undertaken to ascertain the potential protective role of alpha-lipoic acid (ALA) and vitamin E on the same parameters. Highly acute dose of lindane, i.e., 40 mg/kg bw for 18 h exposure, was used for creating lesions in brain. Lipid peroxidation was measured in terms of glutathione peroxidase and thio barbituric acid-reacting substances (TBARS). Various brain regions under investigation were cerebellum and pons-medulla oblongata. Healthy, male, Swiss mice (7–8 weeks old) were allocated into four groups. First group was control, second group was treated with lindane, third group was treated purely with antioxidants, and fourth group received both antioxidants and lindane treatment. Results revealed the significant difference (at 1% and 5% in all groups) in all studied parameters from control. Increased TBARS level in second group suggests that lindane enhances the production of free radicals in studied brain regions. Antioxidants under test are efficient remedy for neurotoxicity caused by lindane. We conclude that lindane manifests toxic effects on brain ATPase and enhances lipid peroxidation. ALA and vitamin E in combination may provide protection against lindane-induced acute toxicity.     

Crystal structure of p44, a constitutively active splice variant of visual arrestin

Visual arrestin specifically binds to photoactivated and phosphorylated rhodopsin and inactivates phototransduction. In contrast, the p44 splice variant can terminate phototransduction by binding to nonphosphorylated light-activated rhodopsin. Here we report the crystal structure of bovine p44 at a resolution of 1.85 Å. Compared to native arrestin, the p44 structure reveals significant differences in regions crucial for receptor binding, namely flexible loop V–VI and polar core regions. Additionally, electrostatic potential is remarkably positive on the N-domain and the C-domain. The p44 structure represents an active conformation that serves as a model to explain the ‘constitutive activity’ found in arrestin variants.