The Journal of Neuroscience, September 1993, K?(9): 39263931
Evidence for in viva Interactions between Neuropeptide Y-related Peptides and CTReceptors in the Mouse Hippocampal Formation
Pascale Bouchard,1s2 Yvan Dumont,’ Alain Fournier,4 Serge St.-Pierre,4 and RQmi Quirioni,2,3 ‘Douglas Hospital Research Center, Verdun, Qukbec, Canada H4H lR3, 2Department of Neurology and Neurosurgery and 3Department of Psychiatry, McGill University, Montreal, Qukbec, Canada, and 41nstitut National de la Recherche Scientifique-Sante, Universitk du Qukbec, Pointe-Claire, Qukbec, Canada H9R lG6
Recently, it was proposed that neuropeptide Y (NPY) and Leonard, 1989; Snyder and Largent, 1989; Chavkin, 1990; Mu- peptide YY (PYY) could act as endogenous ligands for sacchio, 1990; Walker et al., 1990; Ferris et al., 199 1; Itzhak u binding sites, as both NPY and PYY competed with high and Stein, 199 la; Su, 199 1). This assumption is mostly based affinity (nanomolar) for 3H-( +)SKF 10,047 binding sites in rat on the fact that high densities of (r binding sites are found in brain membrane homogenates (Roman et al., 1989). How- various limbic structures, including the hippocampus (Gund- ever, various laboratories failed to replicate these in vitro lath et al., 1986; Contreras et al., 1987b; McLean and Weber, findings. In order to clarify this apparent discrepancy and 1988), and to the high affinity of some neuroleptics (e.g., halo- investigate further possible interactions between NPY and peridol and remoxipride, but not sulpiride) for g sites (Su, 1982, (I related sites, we evaluated the effects of NPY, PYY and 199 1; Tam and Cook, 1984; Taylor and Dekleva, 1987). This homologs, as well as nonrelated peptides, on in viva 3H- suggested the possible development of a new class of u-related (+)SKF 10,047 binding parameters in the mouse hippocam- antipsychotic drugs devoid of dopaminergic activity (Su, 1986; pal formation. As expected, haloperidol (2 mg/kg), a pro- Taylor and Dekleva, 1987; Snyder and Largent, 1989). Addi- totypical ~7 receptor ligand, competed for 90% of in viva tional support for this hypothesis came from observations sug- hippocampal labeling observed following a peripheral intra- gesting that certain g drugs such as N-allylnormetazocine (NANM venous injection of 3H-( +)SKF 10,047. Intracerebroventric- or SKF 10,047) induced hallucinations in man (Keats and Tel- ular injections of 300-3000 pmol of either NPY, PYY, NPY,,,, ford, 1964) and delirium in the chronic spinal dog (Martin et or the Y, agonist Leu3’,ProJ4-NPY inhibited significant pro- al., 1976; Vaupel, 1983) although the genuine u nature of these portions (17-35%) of haloperidol-sensitive in viva 3H-( +)SKF effects remains to be fully established (Quirion et al., 1987; 10,047 hippocampal labeling. However, a Y, receptor ago- Walker et al., 1990). nist, NPY,,,,, and nonrelated peptides such as neurotensin The abundance and discrete distribution of u sites in the and vasoactive intestinal polypeptide, as well as adrenalin, mammalian brain may also reveal the possible existence of failed to alter in vivo3H-( +)SKF 10,047 hippocampal binding. endogenous u-related ligands. Early on, few groups (Quirion et It thus appears that NPY, PYY, and a selective Y, agonist al., 1984; Su et al., 1986; Contreras et al., 1987a; Su and Vaupel, can interact in a concentration-dependant manner, with in 1988; Zhang et al., 1988; Connor and Chavkin, 1991, 1992) viva 3H-( +)SKF 10,047 labeling in the mouse hippocampal reported on the possible isolation of such molecules, although formation. This effect demonstrates selectivity as a Y, ag- their purification to homogeneity still remains to be accom- onist, unrelated peptides, and adrenalin failed to alter in viva plished. Thus, the report by Roman et al. (1989) suggesting that c labeling. This in viva interaction may be relevant to some peptides of the pancreatic polypeptide family, namely, neuro- of the respective biological actions of NPY and a-related peptide Y (NPY) and polypeptide YY (PYY), were able to molecules. compete with high affinities for in vitro 3H-(+)SKF 10,047/u [Key words: neuropeptide Y, peptide YY, sigma receptors, binding sites generated tremendous interests. However, it has N -allylnormetazocine (NANM or SKF 10,047), hippocampus, been difficult to replicate these findings using well-established in vivo binding] in vitro membrane binding assays (Quirion et al., 199 1; Tam and Mitchell, 199 1). The existence of sigma (0) receptor binding sites in the brain On the other hand, evidence has recently accumulated sup- has generated much interest over the past few years likely be- porting the existence of interactions between NPY and u-related cause of their possible involvement in psychosis-related behav- systems, in vivo. For example, Monnet et al. (1990a,b, 1992a- iors (for recent reviews, see Deutsch et al., 1988; Junien and c) have shown that both NPY and u agonists, in a haloperidol- sensitive manner, are able to potentiate N-methyl-D-aspartate (NMDA)-induced firing in the pyramidal CA3 subfield of the Received Nov. 2, 1992; revised Feb. 1, 1993; accepted Mar. 23, 1993. hippocampal formation (but see McQuiston and Colmers, 199 I ; This research project is supported by Program Grant 38 from the Medical Connick et al., 1992). Additionally, NPY and a selective u li- Research Council ofcanada, and a studentship award from Jouveinal Laboratories (Fresnes, France) to P.B. R.Q. is a Chercheur-Boursier “mCrite exceptionnel” and gand, JO 1784, can decrease intestinal transport apparently via A.F. is a Chercheur Boursier from the “Fonds de la Recherche en Santi du haloperidol-sensitive c receptors (Riviere et al., 1990). More- QuCbec.” Correspondence should be addressed to Dr. Rkmi Quirion, Douglas Hospital over, it appears that NPY and homologs, as well as various u Research Center, 6875 Boulevard LaSalle, Verdun, Qu&ec, Canada H4H lR3. ligands, are able to potentiate NMDA-induced 3H-noradrena- Copyright 0 I993 Society for Neuroscience 0270-6474/93/133926-06$05.00/O line release in rat hippocampal slices (Monnet et al., 199 1; Ro- The Journal of Neuroscience, September 1993, 13(9) 3927 man et al., 199 1). Accordingly, we decided to investigate further possible interactions between NPY-related peptides and g re- ceptor sites in the mouse hippocampus using an in vivo binding approach; the hippocampal formation was chosen as this region is most enriched with both g- (Gundlach et al., 1986; Contreras et al., 1987b; McLean and Weber, 1988; Weissman et al., 1988, 1990) and NPY (Martel et al., 1986, 1990a; Lynch et al., 1989; Dumont et al., 1990, 1992,1993) receptors. Our results suggest that NPY, PYY, and a selective agonist of the Y, receptor sub- type can interact with a certain proportion of in vivo 3H-( +)SKF 10,047 labeling in the mouse hippocampus. ” TOT HAL NPY (2mglkg) (1500 pmol) Materials and Methods Materials. ‘H-(+)SKF 10,047 (53 Ci/mmol; Comission Energie Ato- Figure 1. 3H-(+)SKF 10,047-related radioactive material present in mique, Saclay, France) was provided by the Institut de Recherches the mouse hippocampal formation following a peripheral intravenous Jouveinal, Fresnes, France. All NPY-related peptides as well as neu- injection (5 &i per 200 ~1,tail vein; total n = 5 1). 3H-(+)SKF 10,047 rotensin and vasoactive intestinal polypeptide (VIP) were synthesized binding is most likely related to (r sites as haloperidol (2 mg/kg, i.p.; in our laboratories as described earlier (St.-Pierre et al., 1981; Martel n = 1 1) almost completely inhibited (90%) labeling in the mouse hip- et al., 1990b). Adrenalin, haloperidol, trizma base (Tris), NaCl, and pocampus.Similarly, although to a lesserextent, intracerebroventricular polyethyleneimine (PEI) were purchased from Sigma Chemicals (St. injections of NPY (1500 pmol; n = 23) significantly inhibited hippo- Louis, MI). MK-801 was from Research Biochemicals Inc. (Natick, campal ‘H-(+)SKF 10,047 labeling. *, p < 0.005; **, p < 0.001. MA), ether and GF/B Whatman filters were obtained from Fisher (Mon- treal, Canada),and Ecolite TM + was purchasedfrom ICN Biochemicals (Montreal, Canada). presence of haloperidol(2 mg/kg, i.p.) residual 3H-( +)SKF 10,047 Animals. Male CD- 1 mice (20-24 gm) were purchased from Charles River (St.-Constant, Quebec, Canada). Animals were housed in a tem- hippocampal binding accounted for only 1.48 fmol/mg of pro- perature- and humidity-controlled room on a 12 hr: 12 hr light/dark tein, revealing that approximately 90% (13.52 fmol/mg protein) cycle, and were fed ad libitum with standardlaboratory chow and tap of total labeling was sensitive to the prototypical g ligand (Fig. water. They were kept under these conditions for at least 24 hr prior to 1). The NMDA/phencyclidine (PCP) receptor ligand MK-801 the experiment. Animal care was according to protocols and guidelines approved by McGill University and the Canadian Council for Animal did not inhibit the specific )H-(+)SKF 10,047 labeling in the Care. mouse hippocampal formation at intraperitoneal doses of 0.05, Binding experiments. For in vivo binding experiments, mice were 0.1, 0.2, and 0.5 mg/kg (n = 26; data not shown). injected at time (t) = 0 with 2 mg/kg haloperidol (100 ~1, i.p.), MK- 801 (0.05,0.1, 0.2, or 0.5 mg/kg 100 ~1. i.p.), or saline (0.9% NaCl, 100 Competition by NPY-related peptides ~1, i.p.) in order to determine the proportion of in vivo 3H-(+)SKF 10,047 labeling that can be related to r sites. At t = 15 mitt, under light ether As shown in Figure 3, NPY, NPY,_,,, Leu31,Pro34-NPY (a pur- anesthesia, animals received either a peptide injection (3 ~1, i.c.v.) or ported Y, agonist; Fuhlendorff et al., 1990), and PYY were able saline (3 ~1, i.c.v.). Fifteen minutes later (t = 30 min),.animals were to displace approximately one-third of specific in vivo )H-( +)SKF injected in the tail vein with 5 FCi of ‘H-(+)SKF 10,047 (200 ~1, i.v.). 10,047 labeling in the mouse hippocampus. The fragment NPY ,% Animals were killed by dislocation at t = 60 min. Brains were then rapidly removed and hippocampi were dissected on ice and immediately 36(a Y, agonist; Wahlestedt et al., 1986) and the analog desam- homogenized in 1 ml of ice-cold buffer (Tris-HC15 mtq pH 7.4 at 4°C) ido-NPY (NPY-OH) were inactive. As shown in Figure 2, var- using a Teflon/glass Potter-Elvehjem probes (12 strokes). Immediately ious doses ofNPY (300,600, 1000, 1500, and 3000 pmol, i.c.v.) thereafter, 1 ml of ice-cold Tris-HCl buffer was added to this homog- demonstrated that this peptide inhibited the in vivo hippocam- enate before filtration of 1.5 ml of this preparation through three GF/ pal labeling of 3H-(+)SKF 10,047 in a dose-related manner. B glass filters (pretreated for at least 24 hr in buffer containing 0.05% PEI) under vacuum using a 12-hole Millipore CAT apparatus. Filters The minimal effective dose appears to be in the range of 600 were then washedtwice with 5 ml of ice-cold incubation buffer and then pmol while a maximal effect was observed at 1500 pmol, a placed in vials containing 5 ml of Ecolite TM+ scintillation cocktail. higher dose of NPY (3000 pmol) failing to produce a greater Radioactivity was determined using a Beckman LS1800 counter with effect (Fig. 2). 40% efficiency. The remaining 0.5 ml of the homogenatewas kept for protein determination (Lowry et al., 1951). Statistical analyses were The respective potency of various NPY-related peptides to performed using the Student’s t test, p < 0.05 being considered statis- inhibit in vivo 3H-(+)SKF 10,047 labeling in the mouse hip- tically significant. pocampus is shown in Figure 3. At doses of 1500 and 3000 pmol, the homolog PYY most potently inhibited specific 3H- Results (+)SKF 10,047 labeling, its effects being apparently even greater In preliminary experiments we failed to obtain evidence for in than that of NPY. In contrast, NPY-OH failed to inhibit 3H- vitro interactions between NPY, PYY, and 3H-(+)SKF 10,047/ (+)SKF 10,047 labeling (Fig. 3A), as expected for this biolog- a sites as the two peptides, in concentrations ranging from lO-1’ ically inactive analog (Wahlestedt et al., 1986). to 1O-6 M, did not compete for in vitro 3H-( +)SKF 10,047 bind- The fragment NPY,_,, was able to mimic the effect of the full ing in mouse brain membrane preparations. These findings con- NPY molecule on ‘H-(+)SKF 10,047 labeling (Fig. 3B). How- firmed data obtained earlier in the rat brain (Quirion et al., ever, a shorter C-terminal fragment, NPY,,_,,, a purported Y, 199 1; Tam and Mitchell, 1991). agonist (Wahlestedt et al., 1986), failed to alter )H-( +)SKF 10,047 labeling at 1500 pmol (Fig. 3B). On the other hand, the Y, In vivo jH-(+)SKF 10,047 binding in the mouse hippocampus agonist L~u~‘,P~~~~-NPY, was the most potent competitor of in An equivalent of approximately 15 fmol/mg of protein was vivo 3H-(+)SKF 10,047 labeling tested in this study, with a detected in the mouse hippocampus following an injection in profile similar to that of NPY, namely, a dose of 1500 pmol the tail vein of 5 PCi of the u ligand 3H-(+)SKF 10,047. In the inducing a greater effect than that of 3000 pmol (Figs. 2, 3B). 3928 Bouchard et al. * In viva NPYio Interactions
NPY (X 100 pmol) -.. Figure 2. Dose dependency demonstration of the effect of NPY on in l-W NPY PYY PYY -OH -OH vivo ‘H-( +)SKF 10,047 labeling of the mouse hippocampal formation. 15 15 30 15 30 Intracerebroventricular injections of increasing doses of NPY signifi- cantly inhibited in vivo ‘H-(+)SKF 10,047 labeling (total n = 5 1) with (X 100 pmol) a minimally effective dose in the range of 600 pmol (n = 23); a lower dose (300 pmol; n = 25) inhibited binding to a nonsignificant extent; B 1000 omol (n = 23) uroduced a areater inhibition than that of 600 umol. while-maximal effectiveness was observed at 1500 pmol (n = 23); with 3000 pmol (n = 11) being somewhat less effective. *, p < 0.05; **, p < 0.005.
Specificity of NPY for in vivo hippocampal jH-(+)SKF 10,047 labeling As a means to assess the specificity of the effect of NPY and related analogs for in vivo 3H-(+)SKF 10,047 labeling, we in- vestigated next the effects of two other classes ofpeptides, name- ly, neurotensin (1500 pmol) and VIP (1500 pmol), and of the well-known vasoconstrictor/neurotransmitter adrenalin (1500 and 3000 pmol). These three molecules failed to alter in vivo TtJl- 1-36 2-36 2-3613-36 LP LP JH-( +)SKF 10,047 labeling in the mouse hippocampus at doses 15 15 30 15 15 30 tested here (Fig. 4). (X 100 pmol) Discussion The present study demonstrates that (1) NPY and its homolog Figure 3. A, Comparative potencies of NPY, PYY, and NPY-OH to inhibit in vivo ‘H-(+)SKF 10,047 labeling (total n = 51) in the mouse PYY dose-dependently inhibited the in vivo binding of the pro- hippocampal formation. PW at 1500 pmol (n = 13) and 3000 pmol totypical (r ligand ‘H-( +)SKF 10,047 in the mouse hippocampal (n = 8) was slightly more potent than NPY at 1500 pmol (n = 23) to formation; (2) a similar effect is also seen with a Y, (Leu3L,Pro34- inhibit labeling, while NPY-OH at 1500 pmol (n = 7) and 3000 pmol NPY) but not a Y, (NPY ,*-)J receptor agonist, suggesting receptor (n = 13) failed to produce any significant effect. *, p < 0.005. B, Com- parative potencies of NPY ,-)6, C-terminal fragments (NPY,,, and NPY ,3. subtype specificity; (3) a biologically inactive NPY analog, NPY- J, and the analog f,et~~‘,Pro~~-NPY (ZJ) to inhibit in vivo 3H-(+)SKF OH, failed to alter in vivo 3H-(+)SKF 10,047 labeling; and (4) 10,047 labeling (total n = 51) in the mouse hippocampal formation. other biologically active polypeptides such as neurotensin and NPY,-3, at 1500 pmol (n = 20) and 3000 pmol (n = 10) significantly VIP, which are known to induce various cerebrovascular and inhibited )H-(+)SKF 10,047 binding albeit to a lower extent than the full peptide, at 1500 pmol (n = 23). A prototypical Y, fragment, NPY,, neuronal effects (Rioux et al., 198 1; Wilson et al., 1981) and 1A(1500 omol. n = 14). failed to exert anv effect on )H-(+)SKF 10.047 adrenalin failed to modulate in vivo 3H-( +)SKF 10,047 labeling, labeling,-while the Y I’agonist Leu )I Pro);-NPY potent& dompeted for demonstrating the specificity of the interactions between certain labeling at 1500 pmol (n = 14) and ;OOO pmol (n = 7). *, p < 0.05; **, NPY-related peptides and in vivo 3H-(+)SKF 10,047 binding p < 0.005. in the mouse hippocampus. The hippocampal labeling observed following an intravenous of in vivo hippocampal 3H-(+)SKF 10,047 labeling to haloper- injection of 3H-( +)SKF 10,047 is very likely representing bind- idol, together with the ineffectiveness of MK-80 1 to inhibit the ing to G sites that are most abundant in this region (Largent et specific 3H-(+)SKF 10,047 labeling in the mouse hippocampus al., 1986; Contreras et al., 1987b; Weissman et al., 1990). While in vivo, confirms the c nature of the related sites. Our results (+)SKF 10,047 can bind with relatively high affinities to both also extend previously reported in vivo 3H-(+)SKF 10,047/u- PCP and u sites (Su, 1982; Largent et al., 1986; Quirion et al., related binding data (Ferris et al., 1988; Tam et al., 1988; Weiss- 1987; McCann et al., 1989) only the d component is sensitive man et al., 1990). However, it is unclear if, under the present to haloperidol (Su, 1982; Tam and Cook, 1984). Moreover, four assay conditions, in vivo 3H-( +)SKF 10,047 labeling represents different doses (0.05, 0.1, 0.2, and 0.5 mg/kg, i.p.; n = 26) of binding to more than one subtype of (T site. Recently, evidence the high-affinity NMDA/PCP receptor ligand MK-80 1 (Loo et has been obtained to support the existence of at least two classes al., 1987) did not reduce the specific in vivo 3H-( +)SKF 10,047 (al and ~2) of u sites (Hellewell and Bowen, 1990; Itzhak and labeling in the mouse hippocampus. Thus, the high sensitivity Stein, 1991a,b; Itzhak et al., 1991; Su et al., 1991; Quirion et The Journal of Neuroscience, September 1993, 13(9) 3929 al., 1992; Vilner and Bowen, 1992). These two putative subtypes 18 - demonstrate similar affinity for haloperidol, while (+)SKF 10,047 apparently preferentially labels the ~rl sites (Hellewell and Bowen., 1990; Itzhak and Stein, 1991 b; Itzhak et al., 1991; Su et al., 16 - 199 1; Quirion et al., 1992; Vilner and Bowen, 1992) although it can also possibly bind to the a2 site at concentrations com- parable to that used in the present study (5 WCi, i.v.). Additional experiments using other a-related radioligands such as 3H- (+)pentazocine (al) and )H-DTG (in presence of a saturating concentration of dextrallorphan) for u2 sites (DiPaolo et al., 199 1; Bowen et al., 1992) will be required to clarify this issue. Already, in a series of preliminary experiments, we attempted to investigate the in vivo labeling of the mouse hippocampus following intravenous injections of either )H-DTG or )H- TOT NPY NT VIP Ad Ad 15 15 15 15 30 (+)pentazocine. However, in contrast to 3H-( +)SKP 10,047, the amounts of radioactivity recovered in the hippocampal for- (X 100 pmol) mation using either probe were too low to permit adequate F&we 4. Comparative effectsof NPY (n = 23), neurotensin(NT; 1500 pharmacological characterization (1 SO-500 dpm per 5 FCi). pmol, n = 9), VIP (1500 pmol, n = 17),and the catecholamineadrenalin (AAd:1500 nmol. n = 7: 3000 nmol. n = 11)on in viva ,H-(+)SKF 10.047 Moreover, in vivo 3H-DTG labeling was apparently mostly re- labeling (total n = 51) in the m&se hinpocampal formation. At’this stricted to ventricular epithelia as revealed by in vivo autora- concentration, it is evident that only NPY significantly interacted with diography (P. Bouchard, Y. Dumont, A. Foumier, S. St.-Pierre, in vivo 3H-(+)SKF 10,047 labeling. *, p < 0.005. and R. Quirion, unpublished observations). Thus, it appears that other radioligands will have to be developed in order to investigate adequately the in vivo binding profiles of ul and u2 Leu31,Pro34-NPY (Fuhlendorf et al., 1990) behaved as potent sites in the mouse brain. competitors. Taken together, these data may suggest that if a The extent of the competition seen between ‘H-( +)SKF 10,047 metabolite(s) of NPY is responsible for the inhibition of 3H- and NPY-related peptides following their respective in vivo in- (+)SKF 10,047/u labeling, it could be an N-terminal fragment jections also supports the possible labeling by the radioligand likely containing amino acid residue located between positions of two classes of u site. While haloperidol competed for up to 2 and 13. Alternatively, it could be that NPY and some of its 90% of 3H-( +)SKF 10,047 labeling in the mouse hippocampus, related peptides can induce the release of a yet to be character- intracerebroventricular injections of NPY and its homologs in- ized endogenous u ligand that could then inhibit the in vivo hibited approximately one-third of the labeling, suggesting that binding of 3H-(+)SKF 10,047. Recent data by Connor and 3H-( +)SKF 10,047 could interact with subtypes of u-sites, only Chavkin (1991, 1992) are especially interesting in that regard one being accessible to NPY and related peptides. as they provide evidence for the existence of endogenous u li- The precise nature of in vivo interactions between ‘H-( +)SKF gands in the hippocampus. It is also possible that NPY-related 10,047 labeling and NPY remains speculative. It clearly displays peptides, by modulating signal transduction activity, could alter specificity as two other families of well-known peptides, neu- in vivo 3H-(+)SKF 10,047/u labeling. These various possibilities rotensin and VIP, failed to alter in vivo ‘H-( +)SKF 10,047 bind- are currently under investigation. ing under our assay conditions. Similarly, the effects of NPY- The ligand selectivity profile observed here for NPY and its related peptides are unlikely to be related only to changes in homologs is most reminiscent of a Y,-like profile (Wahlestedt cerebral blood flow as adrenalin, a potent constrictor of the et al., 1986, 1990; Fuhlendorff et al., 1990; Quirion et al., 1990; cerebral vasculature, as well as neurotensin and VIP, two pep- Dumont et al., 1992) on the basis of the potent activity of the tides with potent cerebrovascular activities (Rioux et al., 198 1; Y, analog Leu31,Pro34-NPY and the ineffectiveness of NPY,,_,,, Wilson et al., 198 l), failed to modify in vivo )H-(+)SKF 10,047 a Y, agonist (Wahlestedt et al., 1986) to modulate hippocampal labeling of the mouse hippocampus. in vivo ‘H-(+)SKF 10,047 labeling. The high potency of PYY We (Quirion et al., 199 1) and others (Tam and Mitchell, 199 1) in this assay would also exclude an interaction with the newly were unable to obtain clear evidence for the existence of in vitro characterized Y, receptor subtype as PYY was reported to be receptor binding interactions between a variety of U- and NPY- inactive on this receptor class (Balasubramaniam et al., 1990; related molecules. Interestingly, various peptidase inhibitors are Grundemar et al., 1991; Wahlestedt et al., 1992). While it is generally used in in vitro binding assays to insure the integrity certainly too early to claim the existence of possible structural of NPY peptides used either as radioligands and/or competitors homologies between NPY and u receptor classes, the pattern of (Lynch et al., 1989; Mattel et al., 1990a,b; Quirion et al., 1991). in vivo interactions observed in the present study and those of Could it be that an endogenously generated NPY metabolite is others (Monnet et al., 1990a,b) raises interesting possibilities as able to act as a u ligand in vivo? While clear evidence is currently the various NPY receptor subtypes (Rimland et al., 199 1; Her- lacking to support this hypothesis, Contreras et al. (1987a) pro- zog et al., 1992; Larhammar et al., 1992) and likely the al site posed the existence of endogenous u ligands of peptidergic na- (Itzhak and Stein, 199 1b; Itzak et al., 199 1; Bowen at al., 1992; ture. It is thus of interest that only certain NPY-related peptides Quirion et al., 1992) could all belong to the G-protein
Monnet FP, Debonnel G, de Montigny C (1992~) In vivo electro- Su TP, Vaupel DB (1988) Further characterization of an endogenous physiological evidence for a selective modulation of N-methyl-o-as- ligand (“sigmaphin”) for sigma receptors in the brain. Sot Neurosci partate-induced activation in rat CA, dorsal hippocampus by sigma Abstr 14:545. ligands. J Pharmacol Exp Ther 179:44 l-445. Su TP, Weissman AD, Yeh S-Y (1986) Endogenous ligands for sigma Musacchio JM (1990) The psychotomimetic effects of opiates and the opioid receptors in the brain (“sigmaphin”): evidence from binding sigma receptor. Neuropsychopharmacology 3: 19 l-200. assays. Life Sci 38:2199-2210. Q&ion R, DiMaggio DA-French ED, Con&eras PC, Shiloach J, Pert Su TP, Wu XZ, Spivak CE, London ED, Bell JA (1991) Sigma, and CB, Everist H, Pert A, O’Donohue TL (1984) Evidence for an en- sigma, receptors in NCB-20 cells: evidence from electrophysiological dogenous peptide ligand for the phencyclidine receptor. Peptides 5:967- and binding studies. In: NMDA receptor related agents: biochemistry, 973. pharmacology and behavior (Kamenyama T, Nabeshima T, Domino Quirion R, Chicheportiche R, Contreras PC, Johnson KM, Lodge D, EF, eds), pp 2 1 l-2 18. Ann Arbor, MI: NPP. Tam SW, Woods JH, Zukin SR (1987) Classification and nomen- Tam SW, Cook L (1984) u-opiates and certain antipsychotic drugs clature of phencyclidine and sigma receptor sites. Trends Neurosci mutually inhibit (+)-[3H]haloperidol binding in guinea pig brain 10:4441146. membranes. Proc Nat1 Acad Sci USA 8 1:56 18-562 1. Quirion R, Mattel J-C, Dumont Y, Cadieux A, Jolicoeur F, St.-Pierre Tam SW, Mitchell KN (1991) Neuropeptide Y and peptide YY do S, Foumier A (1990) Neuropeptide Y receptors: autoradiographic not bind to brain B and phencyclidine binding sites. Eur J Pharmacol distribution in the brain and structure-activity relationships. Ann NY 193:121-122. Acad Sci 611:58-72. Tam SW, Steinfels GF, Cook L (1988) Biochemical and behavioral Quirion R, Mount H, Chaudieu I, Dumont Y, Boksa P (1991) Neu- aspects of sigma and phencyclidine receptors: similarities and differ- ropeptide Y, polypeptide YY, phencyclidine and sigma related agents: ences. In: Sigma and phencyclidine-like compounds as molecular any relationships? In: NMDA receptor related agents: biochemistry, probes in biology (Domino EF, Kamenka JM, eds), pp 383-396. Ann pharmacology and behavior (Kameyama T, Nabeshima T, Domino Arbor, MI: NPP. EF, eds), pp 203-210. Ann Arbor, MI: NPP. Taylor DP, Dekleva J (1987) Potential antipsychotic BMY 14802 Quirion R, Bowen W, Itzhak Y, Junien JL, Musacchio JM, Rothman selectively binds to sigma sites. Drug Dev Res 11:65-70. RB. Su TP. Tam SW. Tavlor DP (1992) A urouosal for the classi- Vaupel DB (1983) Naltrexone fails to antagonize the effects of PCP fication of sigma binding sites. Trends Pharmacol Sci 13:85-86. and SKF 10,047 in the dog. Eur J Pharmacol92:269-274. Rimland J, Sin W, Sweetnan P, Saijoh K, Nestler EJ, Duman DS (199 1) Vilner BJ, Bowen WD (1992) Characterization of sigma-like binding Sequence and expression of a neuropeptide Y receptor cDNA. Mol sites of NB4 lA3. S-20Y. and N 1 E- 115 neuroblastomas. C6 elioma. Pharmacol 40:869-875. and NG 108- 15 neuroblastoma-glioma hybrid cells: further e;idence Rioux F, Quirion R, St.-Pierre S, Regoli D, Jolicoeur FB, Belanger F, for sigma-2 receptors. In: Multiple sigma and PCP receptor ligands: Barbeau A (198 1) The hypotensive effect of centrally administered mechanisms for neuromodulation and neuroprotection? (Kamenka neurotensin in rats. Eur J Pharmacol 69:241-247. JM. Domino EF. eds). vv 341-353. Ann Arbor. MI: NPP. Riviere PJM, Pascaud X, Junien JL, Porreca F (1990) Neuropeptide Wahlestedt C, Yanaihara N, Hakanson R (1986) Evidence for different Y and JO 1784, a selective (r ligand, alter intestinal ion transport pre-and post-junctional receptors for neuropeptide Y and related pep- through a common, haloperidol-sensitive site. Eur J Pharmacol 187: tides. Regul Peptides 13:307-3 18. 557-559. Wahlestedt C, Grundemar L, Hakanson R, Heilig M, Shen GH, Zu- Roman FJ, Pascaud XP, Dul@ 0, Vauche D, Martin B, Junien JL kowska-Grojec Z, Reis DJ (1990) Neuropeptide Y receptor sub- (1989) Neuropeptide Y and peptide YY interact with rat brain sigma types, Y, and Y,. Ann NY Acad Sci 611~7-26. and PCP binding sites. Eur J Pharmacol 174:301-302. Wahlestedt C, Regunathan S, Reis DJ (1992) Identification of cultured Roman FJ, Pascaud X, Dully 0, Vauche D, Junien JL (199 1) Mod- cells selectively expressing Y, -, Y,-, or Y,-type receptors for neuro- ulation by neuropeptide Y and peptide YY of NMDA effects in rat peptide Y/peptide YY. Life Sci 5O:PL7-PL12. hippocampal slices. Role of sigma receptors. In: NMDA receptor Walker JM, Bowen WD, Walker FO, Matsumoto RR, De Costa B, Rice related agents: biochemistry, pharmacology and behavior (Kameny- KC (1990) Sigma receptors: biology and function. Pharmacol Rev ama T, Nabeshima T, Domino EF, eds), pp 21 l-218. Ann Arbor, 42:355-402. MI: NPP. Weissman AD, Su TP, Hedreen JC, London ED (1988) Sigma recep- Snvder SH, Lament BL (1989) Receptor mechanisms in antipsychotic tors in post-mortem human brains. J Pharmacol Exp Ther 247:29- drug action: focus on sigma receptors. J Neuropsychiatry l-7-15. 33. St.-Pierre S. Lalonde JM. Gendreau M. Ouirion R. Reeoli D. Rioux F Weissman AD, Broussolle EP, London ED (1990) In vivo binding of (1981) Synthesis of pkptides by the’ solid-phase method 6. Neuro- 3H-D-N-allylnormetazocine and ]3H]haloperidol to sigma receptors tensin, fragments and analogues. J Med Chem 24:370-376. in the mouse brain. J Chem Neuroanat 3;347-354. - - Su TP (1982) Evidence for s opioid receptor binding of SH-SKF 10,047 Wilson DA. O’Neill JT. Said SI. Travstman RJ (198 1) Vasoactive to etorphine-inaccessible sites in guinea pig brain. J Pharmacol Exp intestinal’polypeptide and the cerebral circulation. Circ Res 48: 138- Ther 223:284-290. 148. Su TP (1986) HR375: a potential antipsychotic drug that interacts Zhang AZ, Mitchell KN, Cook L, Tam SW (1988) Human endogenous with dopamine D2 receptor and g receptor in the brain. Neurosci Lett brain ligands for sigma and phencyclidine receptors. In: Sigma and 7 11224-228. phencyclidine-like compounds as molecular probes in biology (Dom- Su TP (199 1) c receptors: putative links between nervous, endocrine ino EF, Kamenka JM, eds), pp 335-343. Ann Arbor, MI: NPP. and immune systems. Eur J Biochem 200:633-642.