Serotonin (5-hydroxytryptamine; 5-HT) signaling through the 5-HT2C receptor (5-HT2CR) is essential in normal physiology, whereas aberrant 5-HT2CR function is thought to contribute to the pathogenesis of multiple neural disorders. The 5-HT2CR interacts with specific protein partners, but the impact of such interactions on 5-HT2CR function is poorly understood. Here, we report convergent cellular and behavioral data that the interaction between the 5-HT2CR and protein phosphatase and tensin homolog (PTEN) serves as a regulatory mechanism to control 5-HT2CR-mediated biology but not that of the closely homologous 5-HT2AR. A peptide derived from the third intracellular loop of the human 5-HT2CR [3L4F (third loop, fourth fragment)] disrupted the association, allosterically augmented 5-HT2CR-mediated signaling in live cells, and acted as a positive allosteric modulator in rats in vivo. We identified the critical residues within an 8 aa fragment of the 3L4F peptide that maintained efficacy (within the picomolar range) in live cells similar to that of the 3L4F peptide. Last, molecular modeling identified key structural features and potential interaction sites of the active 3L4F peptides against PTEN. These compelling data demonstrate the specificity and importance of this protein assembly in cellular events and behaviors mediated by 5-HT2CR signaling and provide a chemical guidepost to the future development of drug-like peptide or small-molecule inhibitors as neuroprobes to study 5-HT2CR allostery and therapeutics for 5-HT2CR-mediated disorders.

Nongenomic estrogenic mechanisms offer an opportunity to explain the conundrum of environmental estrogen and plant estrogen effects on cells and animals at very the low concentrations which are prevalent in our environments and diets. Heretofore the actions of these compounds have not been adequately accounted for by laboratory tests utilizing assays for actions only via the genomic pathway of steroid action and the nuclear forms of estrogen receptor α and β. Membrane versions of these receptors, and the newly described GPR30 (7TMER) receptor protein provide explanations for the more potent actions of xenoestrogens. The effects of estrogens on many tissues demand a comprehensive assessment of the receptors, receptor levels, and mechanisms that might be involved, to determine which of these estrogen mimetic compounds are harmful and which might even be used therapeutically, depending upon the life stage at which we are exposed to them.

The specific binding of transcription factors to DNA has been shown to be inhibited by chromatin structure and increased by cooperative interactions with other proteins. Consequently, in situ analysis using chromatin immunoprecipitation offers the most accurate view of transcriptional control. Transient transfection studies and in vitro analyses of IL-1-induced cox-2 transcription in a number of cell types have indicated regulation by either nuclear factor kappa B (NF-kappa B) or CCAAT/enhancer binding protein (C/EBP beta), or both acting cooperatively. To determine the mechanisms of COX-2 (cyclooxygenase or prostaglandin endoperoxide synthase) induction in cultured human myometrial cells in situ, we examined the cross-linking of the RelA subunit of NF-kappa B and C/EBP beta to the cox-2 promoter and flanking sequences. As a control, we inspected the interaction of these transcription factors with the IL-8 gene, which has been shown in other cell types to be activated by the cooperative interaction of NF-kappa B and C/EBP beta. Indeed, both transcription factors were cross-linked to the il-8 promoter after IL-1 treatment, but only RelA was cross-linked to cox-2 DNA. The il-8 promoter was also found to physically interact with proteins cross-linked to sites further upstream. IL-1 treatment also increased polymerase II cross-linking to both promoters and increased histone H4 acetylation at specific sites. These results indicate that modification of chromatin structure is part of the response to IL-1 stimulation. Chromatin immunoprecipitation thus provides critical insight into the mechanisms of COX-2 and IL-8 expression in human myometrial cells.

Peptide-YY (PYY) is a novel enteric peptide that is structurally related to pancreatic polypeptide and neuropeptide-Y. The objectives of the present experiments were to characterize the following aspects of PYY metabolism: the distribution of PYY in the canine gastrointestinal tract, the release of PYY in response to oral ingestion of a mixed meal or intraduodenal (ID) administration of oleic acid, the effect of ileocolectomy on the release of PYY in response to ID administration of oleic acid when transit of chyme to the distal ileum and colon is prevented, the effect of interruption of intramural neural pathways of the small bowel on the release of PYY, and the effect of iv cholecystokinin on the release of PYY. The results of these experiments demonstrate that PYY immunoreactivity is distributed primarily in the terminal ileum, colon, and rectum. Circulating levels of PYY increase significantly (P less than 0.05) within 10-30 min after ingestion of a meal or to ID administration of a fatty acid. Complete interruption of the flow of chyme to the site of PYY-containing cells (i.e. ileum-colon) did not block the release of PYY; however, ileocolectomy abolished the release of PYY in response to ID administration of oleic acid. Severance of intramural neural pathways along the small bowel did not alter the release of PYY in response to an oral meal. Intravenous administration of graded doses of cholecystokinin stimulated the release of PYY in a dose-related manner. The results of these experiments indicate that the release of PYY from the distal ileum and colon is controlled, at least in part, by an extramural neural, endocrine, or a combination of both types of mechanisms which originate in the foregut.

Gender and sex hormones can influence a variety of mental health states, including mood, cognitive development and function, and vulnerability to neurodegenerative diseases and brain damage. Functions of neuronal cells may be altered by estrogens depending upon the availability of different physiological estrogenic ligands; these ligands and their effects vary with life stages, the genetic or postgenetic regulation of receptor levels in specific tissues, or the intercession of competing nonphysiological ligands (either intentional or unintentional, beneficial to health or not). Here we review evidence for how different estrogens (physiological and environmental/dietary), acting via different estrogen receptor subtypes residing in alternative subcellular locations, influence brain functions and behavior. We also discuss the families of receptors and transporters for monoamine neurotransmitters and how they may interact with the estrogenic signaling pathways.