Meanwhile,he found It is in both free and bound forms in the hypothalamus,limbic system and pituitary as well as various peripheral organs, tissues and body fluids. In the pituitary it co-localises with many peptide and non-peptide mediators such as corticotropin-like intermediate peptide (CLIP), adrenocorticotrophic hormone (ACTH), melanocyte-stimulating hormone (MSH), thyroid-stimulating hormone (TSH) and melanin concentrating hormone (MCH). It is abundant in the gut secretory cells and in the pancreas where it co-localises with glucagon.
In addition,In the brain its action may be mediated by NMDA receptors.
It is unknown where DSIP is synthesized.
In vitro it has been found to have a low molecular stability with a half life of only 15 minutes due to the action of a specific aminopeptidase-like enzyme. It has been suggested that in the body it complexes with carrier proteins to prevent degradation, or exists as a component of a large precursor molecule, but as yet no structure or gene has been found for this precursor.
However,evidence supports the current belief that it is regulated by glucocorticoids.
Gimble et al. suggest that DSIP interacts with components of the MAPK cascade and is homologous to glucocorticoid-induced leucine zipper (GILZ).GILZ can be induced by Dexamethasone.It prevents Raf-1 activation, which inhibits phosphorylation and activation of ERK. See  for image showing the pathway analysis of DSIP 
It initially regarded as a candidate sleep-promoting factor. However, the link between DSIP and sleep has never been further characterized, in part because of the lack of isolation of the DSIP gene, protein and possible related receptor. Thus the hypothesis regarding DSIP as a sleep factor is extremely poorly documented and still weak. Although DSIP itself presented a focus of study for a number of researchers, its natural occurrence and biological activity still remains obscure.After that, DSIP structure is different from any other known representative of the various peptide families. In this mini-review we hypothesize the existence of a DSIP-like peptide(s) that is responsible (at least partly) for DSIP-like immunoreactivity and DSIP biological activity.
Roles in endocrine regulation
1.Decreases basal corticotropin level and blocks its release.
2.Stimulates release of luteinizing hormone (LH).
3.Stimulates release of somatoliberin and somatotrophin secretion and inhibits somatostatin secretion.
Roles in physiological processes
1. act as a stress limiting factor.
2.May have a direct or indirect effect on body temperature and alleviating hypothermia.
3.Can normalize blood pressure and myocardial contraction..
4.It has been shown to enhance the efficiency of oxidative phosphorylation in rat mitochondria in vitro, suggesting it may have antioxidant effects.
5.There is also conflicting evidence as to its involvement in sleep patterns. Some studies suggest a link between DSIP and slow-wave sleep (SWS) promotion and suppression of paradoxical sleep, (PS) while some studies show no correlation. Stronger effects on sleep have been noted for the synthesized analogues of DSIP.
6.It may have an impact on human lens epithelial cell function via the MAPK pathway, which is involved in cell proliferation, differentiation, motility, survival, and apoptosis.
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