CADMIUM AND ZINC BIOAVAILABILITY TO SELENASTRUM CAPRICORNUTUM (CHLOROPHYCEAE): ACCIDENTAL METAL UPTAKE AND TOXICITY IN THE PRESENCE OF CITRATE

Toxicities of cadmium (Cd) and zinc (Zn) to the green alga Selenastrum capricornutum Printz were determined over 72 h in defined synthetic media buffered by citrate (FRAQ_CIT ; [citrate] = 100 μM or 5 μM) or nitrilotriacetate (FRAQ_NTA ; [NTA] = 5 μM). Algal sensitivity to free Cd²+ or free Zn²+ in FRAQ_CIT was much higher than in FRAQ_NTA. In parallel experiments, short-term intracellular uptake of radiolabeled ¹⁰⁹Cd was measured as a function of time (0–30 min) in FRAQ_CIT and FRAQ_NTA; for a given free Cd²+ concentration (8, 250, or 610 nM), intracellular accumulation of Cd was consistently higher in FRAQ_CIT than in FRAQ_NTA. Under the same conditions, the alga accumulated ¹⁴C-labeled citrate almost linearly over a 2-h period. Loss of ¹⁰⁹Cd from algal cells that had been prelabeled with the radionuclide occurred slowly, and the loss rate was insensitive to the presence or absence of citrate, indicating that the overall permeability of the algal membrane to Cd was unaffected by citrate. The enhanced bioavailability of Cd in the presence of citrate could be explained by membrane transport of a charged Cd–citrate complex, presumably by accidental transport.     

Transport interactions between cadmium and zinc in roots of bread and durum wheat seedlings

Field studies have shown that the addition of Zn to Cd-containing soils can help reduce accumulation of Cd in crop plants. To understand the mechanisms involved, this study used ¹⁰⁹Cd and ⁶⁵Zn to examine the transport interactions of Zn and Cd at the root cell plasma membrane of bread wheat ( Triticum aestivum L.) and durum wheat ( Triticum turgidum L. var. durum ). Results showed that Cd²⁺ uptake was inhibited by Zn²⁺ and Zn²⁺ uptake was inhibited by Cd²⁺. Concentration-dependent uptake of both Cd²⁺ and Zn²⁺ consisted of a combination of linear binding by cell walls and saturable, Michaelis-Menten influx across the plasma membrane. Saturable influx data from experiments with and without 10 µm concentrations of the corresponding inhibiting ion were converted to double reciprocal plots. The results revealed a competitive interaction between Cd²⁺ and Zn²⁺, confirming that Cd²⁺ and Zn²⁺ share a common transport system at the root cell plasma membrane in both bread and durum wheat. The study suggests that breeding or agronomic strategies that aim to decrease Cd uptake or increase Zn uptake must take into account the potential accompanying change in transport of the competing ion.     

Fine mapping of the FecL locus influencing prolificacy in Lacaune sheep

In the Lacaune sheep population, two major loci influencing ovulation rate are segregating: FecX and FecL . The FecX ^L mutation is a non-conservative substitution (p.Cys53Tyr) in BMP15 that prevents the processing of the protein. Using a statistical approach, FecL has been shown to be an autosomal major gene. A full genome scan localized the FecL locus on sheep chromosome 11. Fine mapping reduced the interval containing FecL to markers BM17132 and FAM117A , corresponding to a synteny block of 1.1 megabases on human chromosome 17, which encompasses 20 genes. The expression of 16 genes from this interval was observed in tissues of the reproductive axis, but expression was not affected in homozygous FecL ^L females. In this interval, a unique haplotype was associated with the FecL ^L mutation. This particular haplotype could be predicted by the DLX3 :c.*803A>G SNP in the 3' UTR sequence of the DLX3 gene. This SNP provided accurate classification of animals (99.5%) as carriers or non-carriers of the mutation and therefore maybe useful in marker assisted selection. A synergistic action of FecL ^L and FecX ^L mutations on both ovulation rate and litter size was demonstrated. Until now, all the Fec genes identified in sheep belong to the bone morphogenetic protein (BMP) system. Based on the human orthologous region, none of the 20 genes in the FecL region corresponds to known molecules in the BMP system. The identification of the FecL ^L mutation could lead to the discovery of a new pathway involved in the regulation of ovulation rate.     

Ca-Cd interaction in the prymnesiophyte Cricosphaera elongata

Abstract. ⁴⁵Ca and ¹⁰⁹Cd uptake were followed in Criscosphaera elongata Prymnesiophyceae. In both cases, after a rapid increase for the first 5 min, the incorporation rate slowed during the hour of observation. Verapamil, a blocker of voltage-dependent slow calcium channels, inhibited ⁴⁵Ca uptake except during the first rapid phase when adsorption should predominate. Cadmium also decreased ⁴⁵Ca labelling, suggesting that the two metals are antagonistic. However, verapamil was shown to augment ¹⁰⁹Cd incorporation, contrary to what occurs in animals cells; this effect is detectable in continuous labelling as well as in pulse experiments. The data support the presence of calcium channels in the alga and suggest several processes in Cd accumulation: adsorption on peripheral envelopes and diffusion of uncharged Cd.     

Characterization of the Functional Activity of Dopamine Ligands at Human Recombinant Dopamine D4 Receptors

Abstract: The human D₄ dopamine receptor has been expressed in Sf9 insect cells where it appears to couple to endogenous G proteins. Increased guanine nucleotide exchange to G proteins is a reflection of receptor activation and can be followed using a [³⁵S]GTPγS binding assay. By measuring D₄ receptor stimulation of [³⁵S]-GTPγS binding we have been able to characterize several dopaminergic compounds for their functional activity at this receptor. In Sf9 cells expressing the D₄ receptor, dopamine, quinpirole, and dp -2-aminodihydroxy-1,2,3,4-tetrahydronaphthalene were all full agonists, whereas (−)-apomorphine appeared to be a partial agonist. No increase in [³⁵S]GTPγS binding was observed for noninfected cells or cells infected with an unrelated sequence. The quinpirole-stimulated [³⁵S]GTPγS binding could be inhibited by the antagonists clozapine, eticlopride, and haloperidol, and a Schild analysis of these data showed that all three compounds were acting as competitive antagonists of D₄ receptors. The rank order of affinities derived from the Schild analysis correlated with that obtained from [³H]spiperone competition binding assays. In conclusion, we have shown that, using this assay system, it is possible to investigate functionally the pharmacology of a recombinant G protein-coupled receptor in the absence of any information regarding the eventual second messenger pathways involved.     

Effect of Lactobacillus gasseri BNR17 on blood glucose levels and body weight in a mouse model of type 2 diabetes

Aims:  To investigate the effect of Lactobacillus gasseri BNR17 isolated from human breast milk on blood glucose and body weight in type 2 diabetic animals.
Methods and results:  db/db mice were divided into one control group and five sample groups; the sample groups received BNR17 (10⁷, 10⁸, 10⁹ and 10¹⁰ CFU) or rosiglitazone (8 mg kg⁻¹) orally twice a day for 12 weeks. BNR17 groups had a dose-dependent reduction in food, water intake and amount of excrement. Body weight loss was not seen in the BNR17 groups. Fasting and postprandial 2 h blood glucose levels were significantly lower in the BNR17 (10¹⁰ CFU) group compared with the control group. HbA1c decreased in the BNR17 group, although it was not statistically significant. During the oral glucose tolerance test, the BNR17 groups exhibited dose-dependent improvement in glucose sensitivity.
Conclusions:  Lactobacillus gasseri BNR17 has a suppressing effect on blood glucose levels and improved diabetic symptoms in db/db mice.
Significance and Impact of the Study:  Blood glucose-lowering lactic acid bacteria are expected to be useful as a therapeutic for treating type 2 diabetes in humans.     

In vitro analysis of intestinal absorption of cadmium and calcium in rainbow trout fed with calcium- and cadmium-supplemented diets

The protective effects of dietary Ca²⁺ supplementation against Cd accumulation in rainbow trout Oncorhynchus mykiss fed with Cd-contaminated food were evaluated in relation to chronic changes in intestinal absorption rates. The changes were measured ' in vitro '. The control diet contained c. 20 mg Ca²⁺ g⁻¹ food and 0·25 μg Cd g⁻¹ food; the experimental diets were supplemented with CaCO₃ and Cd(NO₃)₂·4H₂O to levels of 50 mg Ca²⁺ g⁻¹ food and 300 μg Cd g⁻¹ food, alone and in combination. The Ca²⁺ and Cd absorption rates were measured using radiotracers (⁴⁵Ca, ¹⁰⁹Cd) at total Ca²⁺ and Cd concentrations of 3·0 and 0·12 mmol l⁻¹, respectively in the intestinal saline. Chronically elevated dietary Cd caused a significant increase in Cd absorption rate by up to 10-fold at 30 days in the mid-intestine. The high Ca²⁺ diet prevented this up-regulation of Cd transport rate. Conversely, intestinal Ca²⁺ absorption was significantly increased by two- to five-fold by the Ca²⁺-supplemented diet at 30 days in both the mid- and posterior intestine, and this effect was eliminated when Cd was simultaneously elevated in the diet. Ca²⁺ and Cd probably interact at common pathways and transport mechanisms in the intestine, though independent pathways may also exist.     

Overexpression of δ-Opioid Receptors in Recombinant Baculovirus-Infected Trichoplusia ni"High 5" Insect Cells

Abstract: "High 5" cells derived from Trichoplusia ni ovaries were infected with baculovirus bearing the cDNA of the mouse δ-opioid receptor. The maximal binding capacity for the narcotic antagonist [³H]naltrindole was 1.4 pmol/mg of membrane protein, and that for the agonist [³H][ d -penicillamine², d -penicillamine⁵]enkephalin (DPDPE) was 0.3 pmol/mg. DPDPE proved highly potent in competing with its tritiated analogue at δ-receptors of NG108-15 hybrid cells and of High 5 and Sf9 insect cells. However, in insect cells the opioid was more than 100-fold less effective in competing with [³H]naltrindole as compared with the mammalian cells. This decline in potency was counteracted in a dose-dependent manner by exposure of High 5 membranes to the exogenous G protein G_o, which increased the binding capacity for DPDPE. Functional studies revealed a dose-dependent inhibition (up to 30%) by opioids on forskolin-stimulated cyclic AMP synthesis, and this effect was potentiated by G_o. Quantification of Gα_o and Gα_i disclosed striking differences between Sf9 and High 5 insect cells, both of which overexpressed the cloned δ-opioid receptor. Although no inhibitory G proteins were detected in membranes of Sf9 cells, High 5 cells contained 0.5 pmol of Gα_o/mg of membrane protein, and a 20-fold higher concentration for Gα_i. The distinct G-protein expression in insect cells may be considered an advantage for studying functions of G protein-coupled receptors.     

Binding of [3H]Nitrendipine to Proteins in the Plasma Membrane of Sea Urchin Sperm

The plasma membrane fractions of the sperm of four species of sea urchin, obtained by the method by Podell et al. (24), gave similar electrophoretic profiles of proteins. Several proteins in the membrane fraction from Hemicentrotus pulcherrimus bound [³H]nitrendipine, a specific antagonist of voltage-dependent Ca²⁺channels, added at concentration of about 10⁴times those reported to be effective in muscle and nerve cells. Nifedipine, a close analogue of nitrendipine, decreased the bindings of [³H]nitrendipine to 210, 140, 130 and 110 kDa and increased its bindings to several other proteins. Diltiazem, another type of Ca²⁺channel blocker, enhanced the bindings of [³H]nitrendipine to proteins of 210, 140, 130 and 110 kDa, and decreased its bindings to the other proteins. This effect of diltiazem on the binding of [³H]nitrendipine to proteins in the membrane fraction was similar to its effect on the mammalian excitable membrane fraction. The proteins whose binding to [³H]nitrendipine was blocked by nifedipine and enhanced by diltiazem are Ca²⁺channels.     

[3H]Imipramine Binding of Protein Nature in Human Platelets: Inhibition by 5-Hydroxytryptamine and 5-Hydroxytryptamine Uptake Inhibitors

Abstract: The nature of [³H]imipramine binding to human platelets was investigated. Desipramine and 5-hydroxytryptamine (5-HT) displaced the same amount of binding and the binding was sensitive to protease treatment. The nature of pharmacological inhibition of [³H]imipramine binding was investigated in saturation experiments. Increases in K d without changes in B _max were noted with the addition of 5-HT, desipramine, norzimeldine, or 5-methoxytryptoline. Reductions in B _max without alterations in K _D were obtained when citalopram or clomipramine was added. It is concluded that the [³H]imipramine binding site in human platelets is of protein nature and that this binding site contains the substrate recognition site for 5-HT uptake. In addition, [³H]imipramine and other 5-HT uptake inhibitors have bonds to other parts of the 5-HT uptake carrier or to the surrounding lipid membrane. This additional binding outside the substrate recognition site is not one single site but most likely represents sites that are specific for the chemical structure of each uptake inhibitor, respectively.     

Human Y-79 Retinoblastoma Cells Exhibit Specific Corticotropin-Releasing Hormone Binding Sites

Abstract: In this study we have identified specific binding sites for corticotropin-releasing hormone (CRH) in human Y-79 retinoblastoma cell membranes by using ¹²⁵I-Tyrovine CRH (¹²⁵I-oCRH) as radioligand. Binding at 19°C was rapid with steady state being reached within 20 min, reversible and linear with membrane protein concentration. The ¹²⁵I-oCRH binding was enhanced by Mg²⁺ and inhibited by the GTP analogue guanosine 5'- O -(3'-thiotriphosphate). Y-79 cell membranes exhibited two populations of binding sites, a high-affinity site with an apparent dissociation constant ( K _D) of 1 n M and a low-affinity site with an apparent K _D of 500 n M . ¹²⁵I-oCRH binding was completely antagonized by human/rat CRH, [Met(O)²¹]oCRH, α-helical CRH_9–41, urotensin I, and sauvagine with a rank order of potency similar to that displayed by CRH receptors of other tissues. These data describe for the first time the presence of specific CRH-binding sites in retinal cells. The Y-79 cell line may therefore constitute a valuable model in which to study CRH action on retinal cells.     

Uptake and loss of dissolved zinc by the stickleback Gasterosteus aculeatus L.

Uptake and loss by sticklebacks of both stable zinc and ⁶⁵Zn in hard and soft water have been studied for periods of upto400 h. In calcium-free water, the ⁶⁵Zn uptake curve is approximately asymptotic over a period of 24 h, while in hard water internal ⁶⁵Zn levels are dropping at 24 h. Over 5 h, however, fish in hard tapwater absorb about 3.5 times more ⁶⁵Zn than those in calcium-free water. There is a positive linear relationship between log ⁶⁵Zn uptake and log wet weight of fish. Whole-body concentration factors (c.f.) at 16 h reach a maximum of 12.2 (mean=2.9), highest concentrations of ⁶⁵Zn being found in the gills (mean c.f.=5.l) and lowest concentrations in the gonads (mean c.f.=0.8). Over longer periods (400 h), internal stable zinc levels offish exposed to 1 and 4 p.p.m. Zn²⁺ remain little higher (max 28 %) than controls. ⁶⁵Zn efflux into zinc-free water falls to zero after 5 h, more zinc (78 %) being lost after uptake in tapwater than in calcium-free water (56 %).     

Measurement of the Membrane Potential of Isolated Nerve Terminals by the Lipophilic Cation [3H]Triphenylmethylphosphonium Bromide

Abstract: The lipophilic cation [³H]triphenylrnethylphosphonium bromide ([³H]TPMP⁺) was investigated as a measure of the membrane potential of synaptosomes. Conditions under which [³H]TPMP⁺ achieved an equilibrium distribution were tested. The toxicity of TPMP has been studied relative to its inhibitory effects on [³H]y-aminobutyric acid ([³H]GABA) transport. In some experiments the distribution of ⁸⁶RbZ⁺ and [³H]TPMP⁺ was changed upon incubation in the presence of elevated levels of K⁺, ouabain, or KCN, or at 0°C in a way that would be expected from the membrane potential. In normal incubation conditions a membrane potential of ∼−60 mv was calculated.     

Microbial Spoilage of Fresh Refrigerated Beef Liver

The types and numbers of micro-organisms involved in the spoilage of refrigerated beef liver were studied together with pH, hydration and organoleptic changes of the material. Fresh liver harboured a mixed population ( c . 1 × 10⁵ organisms/g) of Gram positive cocci, chromogens and non-chromogens, sporeformers, presumptive coliforms and Gram negative rods. When samples were rejected organoleptically, after 7–10 days at 5°, the contamination attained levels of c . 7–8 × 10⁷ organisms/g. Spoilage was due to souring; the pH fell from 6·3 (fresh liver) to c . 5·9. Lactic acid bacteria were predominant and Gram negative bacteria did not exceed 1·0 × 10⁶ organisms/g. This type of spoilage is explained by the carbohydrate content of c . 5% in liver. The value of pH appears to be a reliable indicator of liver freshness, with a pH of 6·1 indicating incipient spoilage.     

Rapid Communication: cis-Methyldioxolane Specifically Recognizes the m2 Muscarinic Receptor

Abstract: cis -Methyldioxolane (CD) is a muscarinic receptor agonist. [³H] CD has been used to label a subpopulation of muscarinic receptors described as exhibiting high agonist affinity. Pharmacological evidence suggests that the population of receptors labeled by [³H] CD consists of m2 and/or m4 subtypes; however, no studies have directly addressed the subtype selectivity of [³H] CD. The present study characterizes binding of this ligand to individual human receptor subtypes expressed in transfected Chinese hamster ovary cells. Results indicate that [³H] CD binds with high affinity only to Hm2 receptors but not to all Hm2 receptors. Twenty-eight percent of Hm2 receptors bound [³H] CD with a K _D of 3.5 ± 0.5 nM. Binding was eliminated in the presence of guanosine 5'- O -(3-thiotriphosphate), indicating that the Hm2 receptors labeled by [³H] CD are those that are associated with GDP-bound G protein. Binding of [³H] CD by only a subpopulation of Hm2 receptors is in agreement with data generated from studies of [³H] CD binding in mammalian brain. Because muscarinic receptors have been implicated to play a role in the pathogenesis of both Alzheimer's and Parkinson's disease, as well as the neurotoxicity of organophosphorus compounds, knowledge of the binding specificity of the muscarinic agonist [³H] CD should aid research in these areas.     

The Peripheral-Type Benzodiazepine Receptor Ligands [3H]Ro 5-4864 and [3H]PK 11195 Bind to the Retina of Rabbit, but Not of Turtle

Abstract: The binding of [³H]flunitrazepam, [³H]RO 5-4864, and [³H]PK 11195 to membrane preparations of the retina was studied in the turtle and rabbit. Only a single population of [³H]flunitrazepam binding sites was detected in the turtle, whereas two populations appeared to be present in the rabbit. No specific binding for [³H]RO 5-4864 and [³H]PK 11195 could be detected in the turtle. In rabbit, both ligands bound with high affinity, revealing a significant population of binding sites (K_D values of 24 ± 2.3 and 2.2 ± 0.8 nM, and B_max values of 440 ± 35 and 1,482 ± 110 fmol/mg of protein, respectively). The binding was temperature - and protein-dependent. Displacement studies showed a similar rank order of potency of various unlabeled ligands against both [³H]RO 5-4864 and [³H]PK 11195 (PK 11195 > Ro 5-4864 > flunitrazepam > flumazenil). These results suggest that peripheral-type benzodiazepine receptors are present in the retina of the rabbit, but not of the turtle.     

Dopamine Agonist-Mediated Inhibition of Acetylcholine Release in Rat Striatum Is Modified by Thyroid Hormone Status

Abstract: K⁺-evoked acetyl[³H]choline ([³H]ACh) release was inhibited in a concentration-dependent manner by apomorphine and the D₂ agonist quinpirole in striatal slices prepared from euthyroid and hypothyroid rats. However, there was a significant increase in the maximum inhibition observed with both agonists in the hypothyroid compared with the euthyroid group, which paralleled the increased D₂ agonist sensitivity reported for stereotyped behavior. The D₂ antagonist raclopride decreased, and the D, antagonist SCH 23390 increased, the inhibition of [³H]ACh release by apomorphine, confirming an inhibitory role for D₂ receptors and an opposing role for D₁ receptors. Because there is no difference in D₁ or D₂ receptor concentration between the euthyroid and hypothyroid groups, it is suggested that thyroid hormone modulation of D₂ receptor sensitivity affects a receptor-mediated event. Following intrastriatal injection of pertussis toxin (PTX), apomorphine no longer inhibited [³H]ACh release. In fact, increased [³H]- ACh release was observed, an effect reduced by SCH 23390, providing evidence that D₁ receptors enhance [³H]- ACh release, and confirming that a PTX-sensitive G protein mediates the D₂ response. As it has been reported that thyroid hormones modulate G protein expression, this mechanism may underlie their effect on dopamine agonist- mediated inhibition of ACh.     

OBSERVATIONS ON THE MICROFLORA OF MINCED CHICKEN MEAT IRRADIATED WITH 4 MeV CATHODE RAYS

SUMMARY: Experiments are described in which minced chicken meat, packed anaerobically, was irradiated at room temperature and in the frozen state with a wide range of doses of 4 MeV cathode rays. Sterility was achieved in 14 out of 15 samples which had received 2 × 10⁶ rads or more. Doses of 0·5 and 1·0 × 10⁶ rads allowed survival of a few bacteria/g, usually spore formers. Bacterial counts indicated an approximately logarithmic decrease in numbers at lower doses, while freezing reduced the bactericidal effect.
The storage life at 5° was prolonged only slightly by doses of 5 × 10⁴ and 10 × 10⁴ rads, and highly variable results were obtained with 17·5 × 10⁴ rads. A dose of 25 × 10⁴ rads, however, increased the storage life very considerably. The types of bacteria present initially, and after irradiation with low doses and storage at 5°, were studied. After storage for 12 days or more various types of nonsporing Gram-positive rods were predominant in almost all samples, both control and irradiated. Streptococci were also important where irradiation with 17·5 × 10⁴ and 25 × 10⁴ rads was followed by long storage.     

Altered CB1 receptor-signaling in prefrontal cortex from an animal model of depression is reversed by chronic fluoxetine

Bilateral olfactory bulbectomy in the rat (OBX) induces behavioral, neurochemical, and structural abnormalities similar to those observed in human depression that are normalized after chronic, but not acute, treatment with antidepressants. In our study, OBX animals exhibited significant increases in both CB₁ receptor density ([³H]CP55490 binding) and functionality (stimulation of [³⁵S]GTPγS binding by the cannabinoid (CB) agonist WIN 55212-2) at the prefrontal cortex (PFC). After chronic treatment with fluoxetine (10 mg/kg/day, 14 days, s.c.), OBX-induced hyperactivity in the open-field test was fully abolished. Interestingly, chronic fluoxetine fully reversed the enhanced CB₁-receptor signaling in PFC observed following OBX. The CB agonist Δ⁹-tetrahydrocannabinol (5 mg/kg, i.p., 1 day) did not produce any behavioral effect in sham-operated animals but returned locomotor activity to control values in OBX rats. As both acute administration of Δ⁹-tetrahydrocannabinol and chronic fluoxetine elicited a similar behavioral effect in the OBX rat, it is not unlikely that the regionally selective enhancement of CB₁ receptor-signaling in the PFC could be related with the altered OBX behavior. Our findings reinforce the utility of this animal model to further investigating the implication of the endocannabinoid system in the modulation of emotional processes and its potential role in the adaptive responses to chronic antidepressants.     

Identification of Endothelin Receptor Subtype (ETB) in Human Cerebral Cortex Using Subtype-Selective Ligands

Abstract: Specific endothelin (ET) binding sites were characterized in membranes prepared from human cerebral cortices using binding assay and cross-linking analysis. The presence of immunoreactive (IR) ET-1 was studied by radioimmunoassay. Saturation binding experiments revealed that the K _D and B _max for ¹²⁵I-ET-1 and ¹²⁵l-ET-3 to membranes from gray matter were 25 ± 6 pM and 115 ± 15 fmol/mg of protein and 24 ± 5 p M and 108 ± 13 fmol/mg of protein, respectively. Similar results were obtained for white matter. In the presence of 10 n M sarafotoxin-6c, which is selective for ET_B receptors, ¹²⁵I-ET-1 and ¹²⁵l-ET-3 binding was totally abolished. However, in the presence of 1 μ M BQ123, which is selective for ET_Areceptors, both bindings were not affected. These results suggest that the human cerebral cortex contains only ET_Breceptors. Cross-linking of ¹²⁵I-ET-1 and ¹²⁵l-ET-3 to membranes with disuccinimidyl suberate resulted in the labeling of two bands of 48 and 31 kDa. Concentrations of IR-ET-1 in the gray and white matter were 7.0 ± 3.2 and 2.5 ± 1.7 fmol/g wet weight, respectively. The demonstration of high-affinity ET_B receptors and the presence of IRET-1 suggest that the peptide may act as a neurotransmitter or neuromodulator in the human cerebral cortex.