Characterization of soy-deprestatin, a novel orally active decapeptide that exerts antidepressant-like effects via gut-brain communication.

We found that the orally administered thermolysin digest of ß-conglycinin exhibits antidepressant-like effects in tail suspension and forced swim tests in mice. A comprehensive peptide analysis of the digest using liquid chromatography/mass spectrometry was performed, and LSSTQAQQSY emerged as a candidate antidepressant-like peptide. Orally administered synthetic LSSTQAQQSY exhibited antidepressant-like effects at a dose of 0.3 mg/kg; therefore, we named the decapeptide soy-deprestatin. In contrast, intraperitoneally administered soy-deprestatin was ineffective. We then hypothesized that it acted on the gut, and its signal was transferred to the brain. Indeed, orally administered soy-deprestatin exhibited antidepressant-like activity in sham-treated, but not vagotomized, mice. Oral administration of soy-deprestatin also increased the c-Fos expression in the nucleus of the solitary tract, which receives inputs from the vagus nerve. These results suggested that the antidepressant-like effects were mediated by the vagus nerve. Thermolysin digest- and soy-deprestatin-induced antidepressant-like effects were also blocked by antagonists of serotonin 5-HT1A, dopamine D1, or GABAA receptors. We also clarified the order of receptor activation as 5-HT1A, D1, and GABAA, using selective agonists and antagonists. Taken together, soy-deprestatin may exhibit antidepressant-like effects after oral administration via a novel pathway mediated by 5-HT1A, followed by D1 and GABAA systems. This is the first orally active peptide demonstrating antidepressant-like effects via gut-brain communication.-Mori, Y., Asakura, S., Yamamoto, A., Odagiri, S., Yamada, D., Sekiguchi, M., Wada, K., Sato, M., Kurabayashi, A., Suzuki, H., Kanamoto, R., Ohinata, K. Characterization of soy-deprestatin, a novel orally active decapeptide that exerts antidepressant-like effects via gut-brain communication.

Orally active anti-hypertensive peptides found based on enteroendocrine cell responses to a dipeptide library.

We previously reported that an orally administered dipeptide, Arg-Phe (RF), which causes enteroendocrine cell responses, lowered blood pressure in spontaneously hypertensive rats (SHRs). In this study, we found that Phe-Trp (FW), induced the most potent enteroendocrine cell responses out of total 338 dipeptides. An FW analogue, Phe-Trp-Gly-Lys (FWGK), which was effectively produced by tryptic digestion of bovine serum albumin, decreased blood pressure after oral administration. The minimum effective dose of FWGK (50 µg/kg) was 1/300 of that of RF (15 mg/kg). FWGK stimulated cholecystokinin (CCK) secretion in the enteroendocrine cells and exhibited vasorelaxing and antihypertensive effects via the CCK1 system.

Identification of Rubisco anxiolytic-like peptides (rALPs) by comprehensive analysis of spinach green leaf protein digest.

Rubisco, an enzyme for photosynthetic carbon dioxide fixation, is a major green leaf protein and known as the most abundant protein on the Earth. We found that Rubisco digested mimicking gastrointestinal enzymatic conditions exhibited anxiolytic-like effects after oral administration in mice. Based on a comprehensive peptide analysis of the digest using nanoLC-Orbitrap-MS and the structure-activity relationship of known anxiolytic-like peptides, we identified SYLPPLTT, SYLPPLT and YHIEPV [termed Rubisco anxiolytic-like peptide (rALP)-1, rALP-1(1-7) and rALP-2, respectively], which exhibited potent anxiolytic-like effects after oral administration. The anxiolytic-like effects of rALP-1/rALP-1(1-7) were blocked by a serotonin 5-HT1A receptor antagonist, whereas rALP-2-induced effects were inhibited by a δ-opioid receptor antagonist. In conclusion, novel Rubisco-derived anxiolytic-like peptides, rALP-1/rALP-1(1-7) and rALP-2, act via independent neural pathways.

δ-Opioid receptor activation stimulates normal diet intake but conversely suppresses high-fat diet intake in mice.

The central opioid system is involved in a broadly distributed neural network that regulates food intake. Here, we show that activation of central δ-opioid receptor not only stimulated normal diet intake but conversely suppressed high-fat diet intake as well. [D-Pen(2,5)]-enkephalin (DPDPE), an agonist selective for the δ-receptor, increased normal diet intake after central administration to nonfasted male mice. The orexigenic activity of DPDPE was inhibited by blockade of cyclooxygenase (COX)-2, lipocalin-type prostaglandin D synthase (L-PGDS), D-type prostanoid receptor 1 (DP(1)), and neuropeptide Y (NPY) receptor type 1 (Y1) for PGD(2) and NPY, respectively, suggesting that this was mediated by the PGD(2)-NPY system. In contrast, DPDPE decreased high-fat diet intake in mice fed a high-fat diet. DPDPE-induced suppression of high-fat diet intake was blocked by antagonists of melanocortin 4 (MC(4)) and corticotropin-releasing factor (CRF) receptors but not by knockout of the L-PGDS gene. These results suggest that central δ-opioid receptor activation suppresses high-fat diet intake via the MC-CRF system, independent of the orexigenic PGD(2) system. Furthermore, orally administered rubiscolin-6, an opioid peptide derived from spinach Rubisco, suppressed high-fat diet intake. This suppression was also blocked by centrally administered naltrindole, an antagonist for the δ-receptor, suggesting that rubiscolin-6 suppressed high-fat diet intake via activation of central δ-opioid receptor.

Characterization of Tyr-Leu-Gly, a novel anxiolytic-like peptide released from bovine αS-casein.

We found previously that dipeptide YL exhibits orally active anxiolytic activity comparable to diazepam. The YL sequence is often observed in the primary structure of natural food proteins. In the present study, we investigated whether YL and YL analogues are released from bovine αS-casein by gastrointestinal proteases. YLG, corresponding to αS1-casein (aa 91-93), was more effectively released from αS-casein than YL by pepsin-pancreatin digestion, mimicking gastrointestinal enzymatic conditions. Using the synthetic model peptide, we determined that trypsin cleaved the N terminus of YLG, and elastase and carboxypeptidase contributed to cleave the C-terminus. YLG exhibited orally active anxiolytic-like activity in the elevated plus maze and open-field tests in mice. The anxiolytic-like activity of YLG was inhibited by WAY100135, SCH23390 or bicuculline, antagonists of serotonin 5-HT1A, dopamine D1, and GABA(A) receptors, respectively; however, YLG had no affinity for these receptors. The pepsin-pancreatin digest of αS-Casein also exhibited anxiolytic-like activity. Meanwhile, anxiolytic-like activity of α-casozepine, an αS1-casein-derived decapeptide with YL sequence in the N terminus, was blocked by WAY100135, SCH23390, or bicuculline, equally to YLG and YL; however, it was not detected in the pepsin-pancreatic digest. Taken together, we found that YLG is released after pepsin-pancreatic digestion of αS-casein and exhibits potent anxiolytic-like activity via activation of serotonin, dopamine, and the GABA receptor system.

Importance of uncharged polar residues and proline in the proximal two-thirds (Pro107-Ser128) of the highly conserved region of mouse ileal Na+-dependent bile acid transporter, Slc10a2, in transport activity and cellular expression.

BACKGROUND: SLC10A2-mediated reabsorption of bile acids at the distal end of the ileum is the first step in enterohepatic circulation. Because bile acids act not only as detergents but also as signaling molecules in lipid metabolism and energy production, SLC10A2 is important as the key transporter for understanding the in vivo kinetics of bile acids. SLC10A family members and the homologous genes of various species share a highly conserved region corresponding to Gly104-Pro142 of SLC10A2. The functional importance of this region has not been fully elucidated. RESULTS: To elucidate the functional importance of this region, we previously performed mutational analysis of the uncharged polar residues and proline in the distal one-third (Thr130-Pro142) of the highly conserved region in mouse Slc10a2. In this study, proline and uncharged polar residues in the remaining two-thirds of this region in mouse Slc10a2 were subjected to mutational analysis, and taurocholic acid uptake and cell surface localization were examined. Cell surface localization of Slc10a2 is necessary for bile acid absorption. Mutants in which Asp or Leu were substituted for Pro107 (P107N or P107L) were abundantly expressed, but their cell surface localization was impaired. The S126A mutant was completely impaired in cellular expression. The T110A and S128A mutants exhibited remarkably enhanced membrane expression. The S112A mutant was properly expressed at the cell surface but transport activity was completely lost. Replacement of Tyr117 with various amino acids resulted in reduced transport activity. The degree of reduction roughly depended on the van der Waals volume of the side chains. CONCLUSIONS: The functional importance of proline and uncharged polar residues in the highly conserved region of mouse Slc10a2 was determined. This information will contribute to the design of bile acid-conjugated prodrugs for efficient drug delivery or SLC10A2 inhibitors for hypercholesterolemia treatment.

The vagotomy alleviates the anorectic effect of an excess amount of dietary leucine on rats fed a low-protein diet.

It is well known that large dose of leucine reduces the food intake and causes growth retardation in experimental animals when leucine is given with a low-protein diet. However, the mechanism for the anorectic effect of leucine has not yet been clarified. We demonstrate here that the anorectic effect of leucine was significantly reduced in a vagotomized rat.

Ursodeoxycholic acid protects colon cancer HCT116 cells from deoxycholic acid-induced apoptosis by inhibiting apoptosome formation.

We previously demonstrated that ursodeoxycholic acid (UDC) requires prolonged (≥5 h) preincubation to exhibit effective protection of colon cancer HCT116 cells from deoxycholic acid (DC)-induced apoptosis. Although UDC diminished DC-mediated caspase-9 activation, cytochrome c release from the mitochondria was not inhibited, indicating that UDC acts on the steps of caspase-9 activation. In the present study, therefore, we investigated the effects of UDC on the factors involved in caspase-9 activation. We found that UDC had no significant effect on the expression of antiapoptotic XIAP. Furthermore, UDC did not affect the expression or release of proapoptotic Smac/DIABLO, or the association of XIAP and Smac/DIABLO. In contrast, association of Apaf-1 and caspase-9 stimulated by 500 µM DC was inhibited by UDC pretreatment. Although UDC caused remarkable activation of Akt/PKB, phosphatidylinositol-3-kinase (PI3K) inhibitor did not significantly reduce UDC-mediated cytoprotection. Furthermore, phosphorylation of threonine residues on caspase-9 after UDC pretreatment could not be detected. UDC-mediated cytoprotection was independent of the MAPK pathway, and cyclic AMP (cAMP) analogue did not inhibit DC-induced apoptosis. Our results indicate that UDC protects colon cancer cells from apoptosis induced by hydrophobic bile acids, by inhibiting apoptosome formation independently of the survival signals mediated by the PI3K, MAPK, or cAMP pathways.

Biphasic regulation of cell death and survival by hydrophobic bile acids in HCT116 cells.

A secondary bile acid, namely, deoxycholic acid (DCA), has been known to promote colon tumors; on the other hand, it also induces apoptosis in several human colon cancer cell lines. A hydrophobic primary bile acid, namely, chenodeoxycholic acid (CDCA), exhibits a similar property of apoptosis induction; DCA and CDCA also trigger some specific intracellular signal pathways in the human colon cancer cell line HCT116. In this article, we report that hydrophobic bile acids induce different cellular responses depending on their concentration, that is, a sublethal concentration of hydrophobic bile acids can suppress the apoptosis induced by a higher concentration of DCA. Pretreatment with DCA or CDCA at a concentration of < or = 200 microM for 8 h suppressed the apoptosis induced by 500 microM DCA in HCT116 cells. Under this condition, the association of caspase-9 and Apaf-1 and subsequent activation of caspase-9 were inhibited, but the release of cytochrome c from the mitochondria was not. At 200 microM, DCA and CDCA induced the phosphorylation of Akt and ERK1/2, although these phosphorylations do not appear to be indispensable for the cytoprotection. It is interpreted that prolonged exposure to sublethal concentrations of hydrophobic bile acids induces resistance to apoptosis, leading to promotion of colorectal tumorigenesis.

Soybean resistant protein elevates fecal excretion of cholesterol and bile acids and decreases hepatic cholesterol content in comparison with soybean protein isolate.

The effect of soybean resistant protein (RP) on serum and hepatic cholesterol levels and fecal excretion of steroids was examined. RP decreased cholesterol in the liver, probably due to the stimulated excretion of cholesterol and its metabolites, bile acids. The serum cholesterol level was not different as between RP and other soy-derived proteins.

Mutational analysis of uncharged polar residues and proline in the distal one-third (Thr130-Pro142) of the highly conserved region of mouse Slc10a2.

Solute carrier family member 2 (SLC10A2) reabsorbs bile acids at the distal terminus of the ileum in an Na(+)-dependent manner. Alignment of deduced amino acid sequences of SLC10 family members and homologous genes in various species revealed a highly conserved region that corresponds to Gly(104)-Pro(142) of SLC10A2. To elucidate the functional importance of this region, uncharged polar residues and Pro in the distal one-third of this region in mouse Slc10a2 (mSlc10a2) were submitted to mutational analysis, and taurocholic acid uptake and cell surface localization were evaluated. In addition to mutations that abolished almost all of the transport activity with and without cellular localization failure (P142V and T130A respectively), a mutation that perhaps affected affinity for taurocholic acid was identified (T134A). These results suggest that the highly conserved region contains residues involved in the substrate interaction, function, and cellular localization of mSlc10a2.

Enzymatic digest of whey protein and wheylin-1, a dipeptide released in the digest, increase insulin sensitivity in an Akt phosphorylation-dependent manner.

We investigated the effects of the enzymatic digest of ß-lactoglobulin, a major bovine milk whey protein, on glucose metabolism in KK-Ay mice, an animal model of type II diabetes. In the glucose tolerance test and insulin tolerance test (ITT), the thermolysin digest of ß-lactoglobulin decreased blood glucose levels, suggesting that it increases insulin sensitivity in diabetic KK-Ay mice. The digest also increased phosphorylation of Akt, an intracellular factor activated in response to the insulin receptor activation, in the liver and skeletal muscle. Next, we searched for a bioactive peptide present in the digest that increased the insulin sensitivity. Wheylin-1 is an anxiolytic-like dipeptide (Met-His) isolated from the thermolysin digest of ß-lactoglobulin. Wheylin-1 decreased blood glucose levels in the ITT test and increased hepatic Akt phosphorylation. Wheylin-1 also increased insulin-induced Akt phosphorylation in hepatic HepG2 cells and muscular C2C12 myotube cells. These results suggest that wheylin-1 increases insulin sensitivity in an Akt-dependent manner in vivo and in vitro. Taken together, we found that the thermolysin digest of bovine milk whey ß-lactoglobulin and wheylin-1 increase insulin sensitivity in an Akt system-dependent manner. Wheylin-1 is the first factor found that increases insulin sensitivity in association with Akt-phosphorylation.

A Novel Antihypertensive Peptide Identified in Thermolysin-Digested Rice Bran.

SCOPE: Hypertension is a risk factor for arteriosclerosis. In this study, we investigate the antihypertensive effect of protease-digested rice bran in a spontaneously hypertension rat (SHR) model. We also purify a novel antihypertensive peptide from the digest. METHODS AND RESULTS: Thermolysin-digested rice bran (TRB) is administered to SHRs for 4 weeks, and systolic blood pressure (SBP) was measured weekly using the tail-cuff method. TRB shows an antihypertensive effect in a dose-dependent manner. TRB also reduces angiotensin I-converting enzyme (ACE) activity in lung tissue and serum troponin I levels. TRB is fractionated by HPLC and ACE-inhibitory activity in the HPLC fractions is measured. Peptides LRA and YY are identified from the two fractions with the strongest ACE-inhibitory activity. Amino acid sequence of these peptides are found in a vicilin-like seed storage protein, and identified in rice bran protein using the peptide mass fingerprint method. We confirm that LRA and YY are cleaved by thermolysin digestion of a model synthetic peptide. Orally administered LRA (0.25 mg kg-1 ) or YY (0.5 mg kg-1 ) lowers the SBP of SHRs at 4 h after administration. CONCLUSION: We identify a novel, orally active antihypertensive peptide, LRA from the digest of rice bran protein.

l-Ornithine stimulates growth hormone release in a manner dependent on the ghrelin system.

We found that intraduodenal administration of l-ornithine (l-Orn) stimulates growth hormone (GH) secretion in Wistar rats, and then investigated its mechanism. GH-releasing activity after intraduodenal administration of l-Orn was blocked by [d-Lys3]-GHRP-6, an antagonist of the ghrelin receptor; however, l-Orn (100 µM) has no affinity for the ghrelin receptor, suggesting that the GH-releasing activity of l-Orn is mediated via ghrelin release and activation of the ghrelin receptor. Intraduodenally administered l-Orn increased ghrelin mRNA expression in the duodenum but not in the stomach or hypothalamus. In addition, l-Orn-induced GH-releasing activity was inhibited by propranolol, an antagonist of ß-adrenergic receptor, which is known to be coupled to ghrelin release. In conclusion, intraduodenally administered l-Orn stimulates GH secretion through the sympathetic nervous and ghrelin systems.

Lacto-ghrestatin, a novel bovine milk-derived peptide, suppresses ghrelin secretion.

Ghrelin, an endogenous peptide isolated from the stomach, is known to stimulate food intake after peripheral administration. We found that the enzymatic digest of ß-lactoglobulin decreases ghrelin secretion from the ghrelin-producing cell line MGN3-1. The peptides present in the digest were comprehensively analyzed using the nanoLC-OrbitrapMS. Among them, we identified that the nonapeptide LIVTQTMKG, corresponding to ß-lactoglobulin(1-9), suppresses ghrelin secretion from MGN3-1 cells. We named LIVTQTMKG 'lacto-ghrestatin'. We found that lacto-ghrestatin decreases intracellular cAMP levels and mRNA expression levels of ghrelin production-related genes in MGN3-1 cells. Orally administered lacto-ghrestatin decreases plasma ghrelin levels and food intake in fasted mice. Lacto-ghrestatin is the first food-derived peptide to suppress ghrelin secretion in vitro and in vivo.

l-Ornithine and l-lysine stimulate gastrointestinal motility via transient receptor potential vanilloid 1.

SCOPE: The gastrointestinal (GI) tract senses and responds to intraluminal nutrients and these interactions often affect GI functions. We found that, among basic amino acids, l-ornithine (Orn) and l-lysine (Lys) stimulated but l-arginine (Arg) suppressed GI motility after oral administration (24 mmol/kg) in mice (Orn and Lys, 14.3 and 26.4% promotion; Arg, 7.7% suppression). We investigated the mechanism of the action of Orn and Lys on GI motility. METHODS AND RESULTS: Orn-induced promotion of small intestinal transit was significantly inhibited (p<0.05) by oral administration of capsazepine, a transient receptor potential vanilloid 1 (TRPV1) antagonist. Moreover, the stimulatory effect of Orn and Lys was abolished in TRPV1-knockout mice. In TRPV1-transfected HEK293 cells, Orn and Lys (10 mM) evoked Ca2+ influx, which was blocked by ruthenium red, a TRP channel antagonist. These results suggest that Orn and Lys promote GI motility via activation of TRPV1. The GI motility stimulation by Orn and Lys was also blocked by atropine, a muscarinic acetylcholine receptor (mAChR) antagonist, or NG -nitro-l-arginine methyl ester, a nitric oxide (NO) synthase inhibitor. CONCLUSION: Orally administered Orn and Lys stimulate GI motility via TRPV1, mAChR and NO synthase in mice.

Rational identification of a novel soy-derived anxiolytic-like undecapeptide acting via gut-brain axis after oral administration.

Here we found that the chymotryptic digest of soy ß-conglycinin, a major storage protein, exhibited anxiolytic-like effects in mice. We then searched for anxiolytic-like peptides in the digest. Based on a comprehensive peptide analysis of the chymotryptic digest by high performance liquid chromatograph connected to an LTQ Orbitrap mass spectrometer and the structure-activity relationship of known peptides, we explored anxiolytic-like peptides present in the digest. FLSSTEAQQSY, which corresponds to 323-333 of the ß-conglycinin α subunit [ßCGα(323-333)] emerged as a candidate. Oral administration of synthetic ßCGα(323-333) exhibited anxiolytic-like effects in the elevated plus-maze and open-field test in male mice. Orally administered ßCGα(323-333) exhibited anxiolytic-like effects in sham-operated control mice but not in vagotomized mice. In addition, oral administration of ßCGα(323-333) increased the expression of c-Fos, a marker of neuronal activity, in the nucleus of the solitary tract, which receives inputs from the vagus nerve. These results suggest that the anxiolytic-like effects were mediated by the vagus nerve. The anxiolytic-like effects of ßCGα(323-333) were also blocked by antagonists of the serotonin 5-HT1A, dopamine D1 and GABAA receptors. However ßCGα(323-333) had no affinity for these receptors, suggesting it stimulates the release of endogenous neurotransmitters to activate the receptors. Taken together, a soy-derived undecapeptide, ßCGα(323-333), may exhibit anxiolytic-like effects after oral administration via the vagus nerve and 5-HT1A, D1 and GABAA systems.

Soy-ghretropin, a novel ghrelin-releasing peptide derived from soy protein.

We investigated exogenous secretagogues of ghrelin, which is an orexigenic hormone isolated from the stomach. We found that the tryptic digest of soy ß-conglycinin stimulated ghrelin secretion by the ghrelin-producing cell line, MGN3-1. We then identified a 22-amino acid peptide corresponding to the ß-conglycinin α-subunit(192-213) [ßCGα(192-213)] from an active fraction separated by HPLC. The N-terminal undecapeptide of ßCGα(192-213), NKNPFLFGSNR, exhibited ghrelin-releasing activity at a lower dose than that of ßCGα(192-213). We named NKNPFLFGSNR 'soy-ghretropin', which corresponds to ßCGα(192-202). Neither [des-N(1) K(2) ]-soy-ghretropin nor [des-R(11) ]-soy-ghretropin stimulated ghrelin secretion; hence, both the N- and C-terminal structures of soy-ghretropin were indispensable. Orally administered soy-ghretropin increased plasma ghrelin levels and food intake in vivo. Soy-ghretropin is the first exogenous ghrelin-releasing peptide derived from food protein.

Characteristics of apoptosis in HCT116 colon cancer cells induced by deoxycholic acid.

Hydrophobic bile acids induce apoptosis in both colon cancer cells and hepatocytes. The mechanism by which colon cancer cells respond to bile acids is thought to be different from that of hepatocytes. Therefore, we investigated the characteristics of apoptosis in colon cancer cell line HCT116. Hydrophobic bile acids, i.e., deoxycholic acid (DCA), and chenodeoxycholic acid, induced apoptosis in HCT116 cells. Apoptotic indications were detectable at as early as 30 min and the extent increased in time- and concentration-dependent manners. SDS and a hydrophilic bile acid, cholic acid, did not induce apoptosis even at cytotoxic concentrations. Pretreatment with cycloheximide failed to inhibit apoptosis, suggesting that protein synthesis is not involved in the apoptotic response. Release of cytochrome c from mitochondria and activation of caspase-9 were detectable after 5 and 10 min, respectively, whereas remarkable activation of Bid was not detected. Ursodeoxycholic acid (UDCA) protected HCT116 cells from DCA-induced apoptosis but a preincubation period of > or =5 h was required. Nevertheless, UDCA did not inhibit cytochrome c release from mitochondria. Our results indicate that hydrophobic bile acids induce apoptosis in HCT116 cells by releasing cytochrome c from mitochondria via an undefined but specific mechanism, and that UDCA protects HCT116 cells by acting downstream of cytochrome c release.

Antidepressant-like effect of food-derived pyroglutamyl peptides in mice.

The N-terminal glutamine residue, exposed by enzymatic cleavage of precursor proteins, is known to be modified to a pyroglutamyl residue with a cyclic structure in not only endogenous but also food-derived peptides. We investigated the effects of wheat-derived pyroglutamyl peptides on emotional behaviors. Pyroglutamyl leucine (pyroGlu-Leu, pEL) and pyroglutamyl glutaminyl leucine (pyroGlu-Gln-Leu, pEQL) exhibited antidepressant-like activity in the tail suspension and forced swim tests in mice. pEQL exhibited more potent antidepressant-like activity than pEL after i.p. and i.c.v. administration. pEQL exhibited antidepressant-like activity at a lower dose than Gln-Gln-Leu, suggesting that pyroglutamyl peptide had more potent activity. To examine whether pyroglutamyl peptides increased hippocampus neurogenesis, associated with the effects of antidepressants, we measured 5-bromo-2'-deoxyuridine (BrdU) incorporation. pEL and pEQL increased BrdU-positive cells in the dentate gyrus of the hippocampus. Intriguingly, pEL did not increase hippocampal mRNA and protein expression of brain-derived neurotrophic factor (BDNF), which is a factor associated with both neuropoietic and antidepressive effects. Thus, pyroglutamyl peptides may enhance hippocampal neurogenesis via a pathway independent of BDNF. We also confirmed that pEL and pEQL were produced in the subtilisin digest of major wheat proteins, glutenin and gliadin, after heat treatment. pEL and pEQL are the first peptides derived from wheat proteins to be shown to exhibit an antidepressant-like activity.