Somatostatin (SST), a growth hormone inhibitory peptide, is expressed in endocrine and non-endocrine tissues, immune cells and the central nervous system (CNS). Post-release from secretory or immune ...cells, the first most appreciated role that SST exhibits is the antiproliferative effect in target tissue that served as a potential therapeutic intervention in various tumours of different origins. The SST-mediated in vivo and/or in vitro antiproliferative effect in the tumour is considered direct via activation of five different somatostatin receptor subtypes (SSTR1-5), which are well expressed in most tumours and often more than one receptor in a single cell. Second, the indirect effect is associated with the regulation of growth factors. SSTR subtypes are crucial in tumour diagnosis and prognosis. In this review, with the recent development of new SST analogues and receptor-specific agonists with emerging functional consequences of signaling pathways are promising therapeutic avenues in tumours of different origins that are discussed.
The biological effects of cannabinoids, the major constituents of the ancient medicinal plant
(marijuana) are mediated by two members of the G-protein coupled receptor family, cannabinoid receptors 1 ...(CB1R) and 2. The CB1R is the prominent subtype in the central nervous system (CNS) and has drawn great attention as a potential therapeutic avenue in several pathological conditions, including neuropsychological disorders and neurodegenerative diseases. Furthermore, cannabinoids also modulate signal transduction pathways and exert profound effects at peripheral sites. Although cannabinoids have therapeutic potential, their psychoactive effects have largely limited their use in clinical practice. In this review, we briefly summarized our knowledge of cannabinoids and the endocannabinoid system, focusing on the CB1R and the CNS, with emphasis on recent breakthroughs in the field. We aim to define several potential roles of cannabinoid receptors in the modulation of signaling pathways and in association with several pathophysiological conditions. We believe that the therapeutic significance of cannabinoids is masked by the adverse effects and here alternative strategies are discussed to take therapeutic advantage of cannabinoids.
Obesity is one of the major social and health problems globally and often associated with various other pathological conditions. In addition to unregulated eating behaviour, circulating ...peptide-mediated hormonal secretion and signaling pathways play a critical role in food intake induced obesity. Amongst the many peptides involved in the regulation of food-seeking behaviour, somatostatin (SST) is the one which plays a determinant role in the complex process of appetite. SST is involved in the regulation of release and secretion of other peptides, neuronal integrity, and hormonal regulation. Based on past and recent studies, SST might serve as a bridge between central and peripheral tissues with a significant impact on obesity-associated with food intake behaviour and energy expenditure. Here, we present a comprehensive review describing the role of SST in the modulation of multiple central and peripheral signaling molecules. In addition, we highlight recent progress and contribution of SST and its receptors in food-seeking behaviour, obesity (orexigenic), and satiety (anorexigenic) associated pathways and mechanism.
Sustainable composite materials based on biopolymers and natural fibers have attracted remarkable consideration globally due to their tremendous potential for a variety of applications. However, the ...poor compatibility among the natural fibers and biopolymers causes the reduced mechanical properties of the biocomposites, limiting their application spectrum and acting as one of the major barriers to commercialization. Therefore, surface modification of fibers using chemicals has been explored by several authors. However, most of the chemicals used are hazardous to the environment when used commercially. In the current investigation, sustainable chemicals (sodium bicarbonate and borax) were used to modify the surface of the pineapple leaf fibers (PALFs). Untreated and treated PALF/polylactic acid biocomposites were manufactured using the commercial-scale injection molding machine. The selected chemical treatment strategies were found to be efficient for improving the strength, crystallinity, and thermal properties of pineapple leaf fiber (PALF). An improved adhesion among the fibers and matrix, enhanced strength (tensile, flexural, and impact), and modulus (tensile and flexural) of the biocomposites were also recorded after the treatment. A robust structure-property linkage for PALF and their biocomposites has also been developed.
In the present study, the expression of somatostatin (SST) and somatostatin receptor subtypes (SSTR1–5) was determined in the hypothalamus of wild-type (
wt
) and apolipoprotein D knockout (ApoD
−/−
...) mice brain. SST-like immunoreactivity, while comparable in most regions of hypothalamus, diminished significantly in arcuate nucleus of ApoD
−/−
mice. SSTR1 strongly localized in all major hypothalamic nuclei as well as in the median eminence and ependyma of the third ventricle of
wt
mice brain. SSTR1-like immunoreactivity increases in hypothalamus except in paraventricular nucleus of ApoD
−/−
mice. SSTR2 was well expressed in most of the hypothalamic regions whereas it decreases significantly in ventromedial and arcuate nucleus of ApoD
−/−
mice. SSTR3 and SSTR4-like immunoreactivity increases in ApoD
−/−
mice in all major nuclei of hypothalamus, median eminence, and ependymal cells of third ventricle. SSTR5 is well expressed in ventromedial and arcuate nucleus whereas weakly expressed in paraventricular nucleus. In comparison to
wt
, ApoD
−/−
mice exhibit increased SSTR5-like immunoreactivity in paraventricular nuclei and decreased receptor expression in ventromedial hypothalamus and arcuate nucleus. In conclusion, the changes in hypothalamus of ApoD
−/−
mice may indicate potential role of ApoD in regulation of endocrine functions of somatostatin in a receptor-dependent manner.
Increased ecological awareness, as well as stringent laws and legislation by government agencies, have restricted the use of synthetic fibers as reinforcement. This cognizance shifted the interest of ...engineers and research fraternity toward the use of natural fibers as reinforcement in polymers to develop sustainable composites. The current experimental investigation deals with the extraction and characterization of 'munja' fibers, extracted from Saccharum munja grass. A novel method has been developed for extraction of fibers from the grass followed by extensive evaluation of its physical (structure, density, crystallinity), morphological (surface area, voids), chemical (surface chemistry, hydrophobicity), thermal (thermogravimetry, activation energy), and mechanical properties for its reinforcement potential in polymer matrix composites. Mechanical properties of extracted fibers have also been analyzed in terms of tensile strength and modulus using Weibull's statistical approach. All the aspects have been discussed thoroughly for their contribution in defining the global characteristics of biocomposites. The obtained results substantiate that munja fibers have an enormous potential to be used as a reinforcement in biocomposites, which can be commercially exploited for engineering applications.
Somatostatin (SST) is a growth hormone inhibitory peptide involved in regulation of several physiological responses of cells including neurotransmission, cell migration, maturation, and neurite ...formation. In the present study, we examined the role of SST in
all-trans
retinoic acid (RA)–induced progression of neurite outgrowth in SH-SY5Y cells. We also determined the morphological and developmental changes in prominent intracellular markers of neurite growth including microtubule-associated protein 2 (MAP2), neuron-specific III β-tubulin (TUJ1), and Tau. Here, we present evidence that SST is a molecular determinant in regulating the transition of SH-SY5Y cells from non-neuronal entity to neuronal phenotype in response to RA. The results from present study reveal that SST changes the distributional pattern of MAP2/Tau and TUJ1, and activates extracellular signal–regulated kinase (ERK1/2) signaling pathway through SST receptors (SSTRs). The expression of MAP2 and Tau remains elevated upon treatment with RA and SST alone or in combination. Importantly, we identified that the cells displaying strong co-expression of SST and TUJ1 are more likely to bear elongated neurite formation than cells devoid of such expression. These findings show that the site-specific expression of MAP2 and TUJ1 is an essential determinant of neurite outgrowth in SH-SY5Y cells in RA-mediated differentiation. Taken together, results presented here further substantiates the role of SST in the promotion of neurite formation and elongation in SH-SY5Y cells in combination with RA. Investigating how SST can improve neurite formation in neurodegenerative disease may help to develop new therapeutic approach in improving cognitive function and memory loss.
Purpose
Propylthiouracil (PTU)-induced hypothyroidism is a well-established model for assessing hormonal and morphological changes in thyroid as well as other central and peripheral tissues. ...Somatostatin (SST) is known to regulate hormonal secretion and synthesis in endocrine tissues; however, nothing is currently known about the distribution of SST and its receptor in hypothyroidism.
Method
In the present study, the comparative immunohistochemical distribution of SST and somatostatin receptors (SSTRs) were analyzed in PTU-induced hypothyroid rats. Rats were treated with PTU for 15 days followed by a co-administration of levothyroxine (LVT) for 15 days. After PTU and LVT treatments (day 30), rats were further administered LVT alone for 15 more days (day 45). The subcellular distribution of SST and SSTR subtypes was determined by peroxidase immunohistochemistry in the thyroid gland collected from control and treated rats.
Results
SST and SSTR subtypes were found to be moderately expressed in control thyroid tissues. SST and SSTR subtypes like immunoreactivity increased significantly in follicular and parafollicular epithelial cells in the thyroid of PTU-treated rats. The PTU-induced changes in the expression of SST and SSTR subtypes were suppressed by the administration of the LVT. In addition to thyroid tissues, SST and SSTRs expression was also changed in non-follicular tissues including blood vessels, smooth muscle cells, and connective tissue following treatments.
Conclusion
The present study revealed a distinct subcellular distribution of SST and SSTR subtypes in the thyroid and provides a new insight for the role of SST and SSTR subtypes in hypothyroidism in addition to its well-established role in negative regulation of hormonal secretion.
The current research endeavor, explores the thermal, mechanical, and degradation behavior of alkaline treated banana fibers reinforced polypropylene composites. Composites incorporating BF (20% w: w) ...treated with NaOH (5% w: v) aqueous solution were developed using extrusion-injection molding processes. After chemical treatment, the tensile, flexural and impact strength of the composite increases by 3.8%, 5.17%, and 11.50%, respectively. Scanning electron microscope (SEM) observations of tested specimens confirm the fiber pull out and fiber fracture as the main reasons for failure of developed composites under tensile and impact loading. The specimens were exposed to two different environments, water immersion and soil burial for 5 weeks for the degradation studies. The degradation behavior of composites was measured in terms of variation in weight and mechanical properties (tensile, flexural, and impact). The maximum degradation in mechanical properties was observed for the composites buried under soil. The composite lost 7.69%, 12.06%, and 3.27% of tensile, flexural, and impact strength, respectively.
Pain relief is the principal action of opioids. Somatostatin (SST), a growth hormone inhibitory peptide is also known to alleviate pain even in cases when opioids fail. Recent studies have shown that ...mice are prone to sustained pain and devoid of analgesic effect in the absence of somatostatin receptor 4 (SSTR4). In the present study, using brain slices, cultured neurons and HEK-293 cells, we showed that SSTR4 and δ-Opioid receptor (δOR) exist in a heteromeric complex and function in synergistic manner. SSTR4 and δOR co-expressed in cortical/striatal brain regions and spinal cord. Using cultured neuronal cells, we describe the heterogeneous complex formation of SSTR4 and δOR at neuronal cell body and processes. Cotransfected cells display inhibition of cAMP/PKA and co-activation of SSTR4 and δOR oppose receptor trafficking induced by individual receptor activation. Furthermore, downstream signaling pathways either associated with withdrawal or pain relief are modulated synergistically with a predominant role of SSTR4. Inhibition of cAMP/PKA and activation of ERK1/2 are the possible cellular adaptations to prevent withdrawal induced by chronic morphine use. Our results reveal direct intra-membrane interaction between SSTR4 and δOR and provide insights for the molecular mechanism for the anti-nociceptive property of SST in combination with opioids as a potential therapeutic approach to avoid undesirable withdrawal symptoms.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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