1
|
Ko B, Jang Y, Kwak SH, You H, Kim JH, Lee JE, Park HD, Kim SK, Goddard WA, Han JH, Kim YC. Discovery of 3-Phenyl Indazole-Based Novel Chemokine-like Receptor 1 Antagonists for the Treatment of Psoriasis. J Med Chem 2023; 66:14564-14582. [PMID: 37883692 DOI: 10.1021/acs.jmedchem.3c01011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2023]
Abstract
Chemokine-like receptor 1 (CMKLR1)─a G protein-coupled receptor─has functional roles in the immune system and related diseases, including psoriasis and metabolic diseases. Psoriasis is a chronic inflammatory disease characterized by skin redness, scaliness, and itching. In this study, we sought to develop novel CMKLR1 antagonists by screening our in-house GPCR-targeting compound library. Moreover, we optimized a phenylindazole-based hit compound with antagonistic activities and evaluated its oral pharmacokinetic properties in a murine model. A structure-based design on the human CMKLR1 homology model identified S-26d as an optimized compound that serves as a potent and orally available antagonist with a pIC50 value of 7.44 in hCMKLR1-transfected CHO cells. Furthermore, in the imiquimod-induced psoriasis-like mouse model, oral administration of S-26d for 1 week significantly alleviated modified psoriasis area and severity index scores (severity of erythema, scaliness, skin thickness) compared with the control group.
Collapse
Affiliation(s)
- Bongki Ko
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea
| | - Yongsoo Jang
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea
| | - Seung-Hwa Kwak
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea
| | - Hyun You
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea
| | - Jeong-Hyun Kim
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea
| | - Jung-Eun Lee
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea
| | - Hee Dong Park
- Innovo Therapeutics Inc., Daeduck Biz Center C-313, 17 Techno 4-ro, Yuseong-gu, Daejeon 34013, Republic of Korea
| | - Soo-Kyung Kim
- Materials and Process Simulation Center, California Institute of Technology, Pasadena, California 91125, United States
| | - William A Goddard
- Materials and Process Simulation Center, California Institute of Technology, Pasadena, California 91125, United States
| | - Jung Hyun Han
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea
- Department of Dermatology, Saint John of God Hospital, Gwangju 61245, Republic of Korea
| | - Yong-Chul Kim
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea
- Center for AI-Applied High Efficiency Drug Discovery (AHEDD), Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea
| |
Collapse
|
2
|
Thirumalai D, Hyeon C, Zhuravlev PI, Lorimer GH. Symmetry, Rigidity, and Allosteric Signaling: From Monomeric Proteins to Molecular Machines. Chem Rev 2019; 119:6788-6821. [DOI: 10.1021/acs.chemrev.8b00760] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- D. Thirumalai
- Department of Chemistry, The University of Texas, Austin, Texas 78712, United States
| | - Changbong Hyeon
- Korea Institute for Advanced Study, Seoul 02455, Republic of Korea
| | - Pavel I. Zhuravlev
- Biophysics Program, Institute for Physical Science and Technology and Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States
| | - George H. Lorimer
- Biophysics Program, Institute for Physical Science and Technology and Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States
| |
Collapse
|
3
|
Ikeda M, Sugihara M, Suwa M. SEVENS: a database for comprehensive GPCR genes obtained from genomes: -Update to 68 eukaryotes. Biophys Physicobiol 2018; 15:104-110. [PMID: 29892516 PMCID: PMC5992857 DOI: 10.2142/biophysico.15.0_104] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 03/25/2018] [Indexed: 12/01/2022] Open
Abstract
We report the development of the SEVENS database, which contains information on G-protein coupled receptor (GPCR) genes that are identified with high confidence levels (A, B, C, and D) from various eukaryotic genomes, by using a pipeline comprising bioinformatics softwares, including a gene finder, a sequence alignment tool, a motif and domain assignment tool, and a transmembrane helix predictor. SEVENS compiles detailed information on GPCR genes, such as chromosomal mapping position, phylogenetic tree, sequence similarity to known genes, and protein function described by motif/domain and transmembrane helices. They are presented in a user-friendly interface. Because of the comprehensive gene findings from genomes, SEVENS contains a larger data set than that of previous databases and enables the performance of a genome-scale overview of all the GPCR genes. We surveyed the complete genomes of 68 eukaryotes, and found that there were between 6 and 3,470 GPCR genes for each genome (Level A data). Within these genes, the number of receptors for various molecules, including biological amines, peptides, and lipids, were conserved in mammals, birds, and fishes, whereas the numbers of odorant receptors and pheromone receptors were highly diverse in mammals. SEVENS is freely available at http://sevens.cbrc.jp or http://sevens.chem.aoyama.ac.jp.
Collapse
Affiliation(s)
- Masami Ikeda
- Aoyama Gakuin University, College of Science and Engineering, Sagamihara, Kanagawa 252-5258, Japan
| | - Minoru Sugihara
- Meiji Pharmaceutical University, Pharmaceutical Education and Research Center, Kiyose, Tokyo 204-8588, Japan
| | - Makiko Suwa
- Aoyama Gakuin University, College of Science and Engineering, Sagamihara, Kanagawa 252-5258, Japan
| |
Collapse
|
4
|
Structural heterogeneity of the μ-opioid receptor's conformational ensemble in the apo state. Sci Rep 2017; 8:45761. [PMID: 28368046 PMCID: PMC5377942 DOI: 10.1038/srep45761] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 03/03/2017] [Indexed: 01/17/2023] Open
Abstract
G-protein coupled receptors (GPCRs) are the largest and most pharmaceutically relevant family of membrane proteins. Here, fully unbiased, enhanced sampling simulations of a constitutively active mutant (CAM) of a class A GPCR, the μ-opioid receptor (μOR), demonstrates repeated transitions between the inactive (IS) and active-like (AS-L) states. The interconversion features typical activation/inactivation patterns involving established conformational rearrangements of conserved residues. By contrast, wild-type μOR remains in IS during the same course of simulation, consistent with the low basal activity of the protein. The simulations point to an important role of residue W2936.48 at the "toggle switch" in the mutation-induced constitutive activation. Such role has been already observed for other CAMs of class A GPCRs. We also find a significantly populated intermediate state, rather similar to IS. Based on the remarkable accord between simulations and experiments, we suggest here that this state, which has escaped so far experimental characterization, might constitute an early step in the activation process of the apo μOR CAM.
Collapse
|
5
|
Chen H, Zhu H, Liu P, Li L. A study on the conformational space of the all-trans retinal deprotonated Schiff base. COMPUT THEOR CHEM 2016. [DOI: 10.1016/j.comptc.2016.08.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
6
|
Kim JH, Kim SK, Lee JH, Kim YJ, Goddard WA, Kim YC. Homology modeling and molecular docking studies of Drosophila and Aedes sex peptide receptors. J Mol Graph Model 2016; 66:115-22. [DOI: 10.1016/j.jmgm.2016.03.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Revised: 03/07/2016] [Accepted: 03/24/2016] [Indexed: 11/29/2022]
|
7
|
Computational based functional analysis of Bacillus phytases. Comput Biol Chem 2016; 60:53-8. [DOI: 10.1016/j.compbiolchem.2015.11.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 09/25/2015] [Accepted: 11/06/2015] [Indexed: 11/19/2022]
|
8
|
Cong X, Campomanes P, Kless A, Schapitz I, Wagener M, Koch T, Carloni P. Structural Determinants for the Binding of Morphinan Agonists to the μ-Opioid Receptor. PLoS One 2015; 10:e0135998. [PMID: 26280453 PMCID: PMC4539194 DOI: 10.1371/journal.pone.0135998] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Accepted: 07/28/2015] [Indexed: 01/05/2023] Open
Abstract
Atomistic descriptions of the μ-opioid receptor (μOR) noncovalently binding with two of its prototypical morphinan agonists, morphine (MOP) and hydromorphone (HMP), are investigated using molecular dynamics (MD) simulations. Subtle differences between the binding modes and hydration properties of MOP and HMP emerge from the calculations. Alchemical free energy perturbation calculations show qualitative agreement with in vitro experiments performed in this work: indeed, the binding free energy difference between MOP and HMP computed by forward and backward alchemical transformation is 1.2±1.1 and 0.8±0.8 kcal/mol, respectively, to be compared with 0.4±0.3 kcal/mol from experiment. Comparison with an MD simulation of μOR covalently bound with the antagonist β-funaltrexamine hints to agonist-induced conformational changes associated with an early event of the receptor’s activation: a shift of the transmembrane helix 6 relative to the transmembrane helix 3 and a consequent loss of the key R165-T279 interhelical hydrogen bond. This finding is consistent with a previous proposal suggesting that the R165-T279 hydrogen bond between these two helices indicates an inactive receptor conformation.
Collapse
Affiliation(s)
- Xiaojing Cong
- Laboratory of Computational Biophysics, German Research School for Simulation Sciences GmbH, Joint venture of RWTH Aachen University and Forschungszentrum Jülich, 52425 Jülich, Germany
- Computational Biomedicine section (IAS-5), Institute of Advanced Simulation (IAS), Forschungszentrum Jülich, 52425 Jülich, Germany
- Computational Biomedicine section (INM-9), Institute of Neuroscience and Medicine (INM), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Pablo Campomanes
- Laboratory of Computational Biophysics, German Research School for Simulation Sciences GmbH, Joint venture of RWTH Aachen University and Forschungszentrum Jülich, 52425 Jülich, Germany
- Computational Biomedicine section (IAS-5), Institute of Advanced Simulation (IAS), Forschungszentrum Jülich, 52425 Jülich, Germany
- Computational Biomedicine section (INM-9), Institute of Neuroscience and Medicine (INM), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Achim Kless
- Grünenthal Innovation, Grünenthal GmbH, 52078 Aachen, Germany
| | - Inga Schapitz
- Grünenthal Innovation, Grünenthal GmbH, 52078 Aachen, Germany
| | - Markus Wagener
- Grünenthal Innovation, Grünenthal GmbH, 52078 Aachen, Germany
| | - Thomas Koch
- Grünenthal Innovation, Grünenthal GmbH, 52078 Aachen, Germany
| | - Paolo Carloni
- Laboratory of Computational Biophysics, German Research School for Simulation Sciences GmbH, Joint venture of RWTH Aachen University and Forschungszentrum Jülich, 52425 Jülich, Germany
- Computational Biomedicine section (IAS-5), Institute of Advanced Simulation (IAS), Forschungszentrum Jülich, 52425 Jülich, Germany
- Computational Biomedicine section (INM-9), Institute of Neuroscience and Medicine (INM), Forschungszentrum Jülich, 52425 Jülich, Germany
- * E-mail:
| |
Collapse
|
9
|
Bioinformatics tools for predicting GPCR gene functions. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 796:205-24. [PMID: 24158807 DOI: 10.1007/978-94-007-7423-0_10] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
The automatic classification of GPCRs by bioinformatics methodology can provide functional information for new GPCRs in the whole 'GPCR proteome' and this information is important for the development of novel drugs. Since GPCR proteome is classified hierarchically, general ways for GPCR function prediction are based on hierarchical classification. Various computational tools have been developed to predict GPCR functions; those tools use not simple sequence searches but more powerful methods, such as alignment-free methods, statistical model methods, and machine learning methods used in protein sequence analysis, based on learning datasets. The first stage of hierarchical function prediction involves the discrimination of GPCRs from non-GPCRs and the second stage involves the classification of the predicted GPCR candidates into family, subfamily, and sub-subfamily levels. Then, further classification is performed according to their protein-protein interaction type: binding G-protein type, oligomerized partner type, etc. Those methods have achieved predictive accuracies of around 90 %. Finally, I described the future subject of research of the bioinformatics technique about functional prediction of GPCR.
Collapse
|
10
|
Lee Y, Choi S, Hyeon C. Mapping the intramolecular signal transduction of G-protein coupled receptors. Proteins 2013; 82:727-43. [PMID: 24166702 DOI: 10.1002/prot.24451] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Revised: 09/13/2013] [Accepted: 10/10/2013] [Indexed: 11/07/2022]
Abstract
G-protein coupled receptors (GPCRs), a major gatekeeper of extracellular signals on plasma membrane, are unarguably one of the most important therapeutic targets. Given the recent discoveries of allosteric modulations, an allosteric wiring diagram of intramolecular signal transductions would be of great use to glean the mechanism of receptor regulation. Here, by evaluating betweenness centrality (CB ) of each residue, we calculate maps of information flow in GPCRs and identify key residues for signal transductions and their pathways. Compared with preexisting approaches, the allosteric hotspots that our CB -based analysis detects for A2 A adenosine receptor (A2 A AR) and bovine rhodopsin are better correlated with biochemical data. In particular, our analysis outperforms other methods in locating the rotameric microswitches, which are generally deemed critical for mediating orthosteric signaling in class A GPCRs. For A2 A AR, the inter-residue cross-correlation map, calculated using equilibrium structural ensemble from molecular dynamics simulations, reveals that strong signals of long-range transmembrane communications exist only in the agonist-bound state. A seemingly subtle variation in structure, found in different GPCR subtypes or imparted by agonist bindings or a point mutation at an allosteric site, can lead to a drastic difference in the map of signaling pathways and protein activity. The signaling map of GPCRs provides valuable insights into allosteric modulations as well as reliable identifications of orthosteric signaling pathways.
Collapse
Affiliation(s)
- Yoonji Lee
- National Leading Research Lab (NLRL) of Molecular Modeling and Drug Design College of Pharmacy Graduate School of Pharmaceutical Sciences and Global Top 5 Research Program, Ewha Womans University, Seoul, 120-750, Korea
| | | | | |
Collapse
|
11
|
Gao J, Huang Q, Wu D, Zhang Q, Zhang Y, Chen T, Liu Q, Zhu R, Cao Z, He Y. Study on human GPCR–inhibitor interactions by proteochemometric modeling. Gene 2013; 518:124-31. [DOI: 10.1016/j.gene.2012.11.061] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Accepted: 11/27/2012] [Indexed: 11/15/2022]
|
12
|
Rizvanovic A, Amundin M, Laska M. Olfactory discrimination ability of Asian elephants (Elephas maximus) for structurally related odorants. Chem Senses 2012; 38:107-18. [PMID: 23246848 DOI: 10.1093/chemse/bjs097] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Using a food-rewarded two-choice instrumental conditioning paradigm, we assessed the ability of Asian elephants, Elephas maximus, to discriminate between 2 sets of structurally related odorants. We found that the animals successfully discriminated between all 12 odor pairs involving members of homologous series of aliphatic 1-alcohols, n-aldehydes, 2-ketones, and n-carboxylic acids even when the stimuli differed from each other by only 1 carbon. With all 4 chemical classes, the elephants displayed a positive correlation between discrimination performance and structural similarity of odorants in terms of differences in carbon chain length. The animals also successfully discriminated between all 12 enantiomeric odor pairs tested. An analysis of odor structure-activity relationships suggests that a combination of molecular structural properties rather than a single molecular feature may be responsible for the discriminability of enantiomers. Compared with other species tested previously on the same sets of odor pairs (or on subsets thereof), the Asian elephants performed at least as well as mice and clearly better than human subjects, squirrel monkeys, pigtail macaques, South African fur seals, and honeybees. Further comparisons suggest that neither the relative nor the absolute size of the olfactory bulbs appear to be reliable predictors of between-species differences in olfactory discrimination capabilities. In contrast, we found a positive correlation between the number of functional olfactory receptor genes and the proportion of discriminable enantiomeric odor pairs. Taken together, the results of the present study support the notion that the sense of smell may play an important role in regulating the behavior of Asian elephants.
Collapse
|
13
|
Ueno Y, Kawasaki K, Saito O, Arai M, Suwa M. Folding elastic transmembrane helices to fit in a low-resolution image by electron microscopy. J Bioinform Comput Biol 2011; 9 Suppl 1:37-50. [PMID: 22144252 DOI: 10.1142/s0219720011005720] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Revised: 09/02/2011] [Accepted: 09/15/2011] [Indexed: 11/18/2022]
Abstract
Structure prediction of membrane proteins could be constrained and thereby improved by introducing data of the observed molecular shape. We studied a coarse-grained molecular model that relied on residue-based dummy atoms to fold the transmembrane helices of a protein in the observed molecular shape. Based on the inter-residue potential, the α-helices were folded to contact each other in a simulated annealing protocol to search optimized conformation. Fitting the model into a three-dimensional volume was tested for proteins with known structures and resulted in a fairly reasonable arrangement of helices. In addition, the constraint to the packing transmembrane helix with the two-dimensional region was tested and found to work as a very similar folding guide. The obtained models nicely represented α-helices with the desired slight bend. Our structure prediction method for membrane proteins well demonstrated reasonable folding results using a low-resolution structural constraint introduced from recent cell-surface imaging techniques.
Collapse
Affiliation(s)
- Yutaka Ueno
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST) Tsukuba, 1-1 Umezono Central-2, Tsukuba, Ibaraki, 305-8568, Japan.
| | | | | | | | | |
Collapse
|
14
|
Lampert TJ, Coleman KD, Hennessey TM. A knockout mutation of a constitutive GPCR in Tetrahymena decreases both G-protein activity and chemoattraction. PLoS One 2011; 6:e28022. [PMID: 22140501 PMCID: PMC3226668 DOI: 10.1371/journal.pone.0028022] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Accepted: 10/30/2011] [Indexed: 11/18/2022] Open
Abstract
Although G-protein coupled receptors (GPCRs) are a common element in many chemosensory transduction pathways in eukaryotic cells, no GPCR or regulated G-protein activity has yet been shown in any ciliate. To study the possible role for a GPCR in the chemoresponses of the ciliate Tetrahymena, we have generated a number of macronuclear gene knockouts of putative GPCRs found in the Tetrahymena Genome database. One of these knockout mutants, called G6, is a complete knockout of a gene that we call GPCR6 (TTHERM_00925490). Based on sequence comparisons, the Gpcr6p protein belongs to the Rhodopsin Family of GPCRs. Notably, Gpcr6p shares highest amino acid sequence homologies to GPCRs from Paramecium and several plants. One of the phenotypes of the G6 mutant is a decreased responsiveness to the depolarizing ions Ba2+ and K+, suggesting a decrease in basal excitability (decrease in Ca2+ channel activity). The other major phenotype of G6 is a loss of chemoattraction to lysophosphatidic acid (LPA) and proteose peptone (PP), two known chemoattractants in Tetrahymena. Using microsomal [35S]GTPγS binding assays, we found that wild-type (CU427) have a prominent basal G-protein activity. This activity is decreased to the same level by pertussis toxin (a G-protein inhibitor), addition of chemoattractants, or the G6 mutant. Since the basal G-protein activity is decreased by the GPCR6 knockout, it is likely that this gene codes for a constitutively active GPCR in Tetrahymena. We propose that chemoattractants like LPA and PP cause attraction in Tetrahymena by decreasing the basal G-protein stimulating activity of Gpcr6p. This leads to decreased excitability in wild-type and longer runs of smooth forward swimming (less interrupted by direction changes) towards the attractant. Therefore, these attractants may work as inverse agonists through the constitutively active Gpcr6p coupled to a pertussis-sensitive G-protein.
Collapse
Affiliation(s)
- Thomas J Lampert
- Department of Biological Sciences, University at Buffalo, Amherst, New York, United States of America
| | | | | |
Collapse
|
15
|
Arvidsson J, Amundin M, Laska M. Successful acquisition of an olfactory discrimination test by Asian elephants, Elephas maximus. Physiol Behav 2011; 105:809-14. [PMID: 21889524 DOI: 10.1016/j.physbeh.2011.08.021] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Revised: 08/17/2011] [Accepted: 08/18/2011] [Indexed: 11/17/2022]
Abstract
The present study demonstrates that Asian elephants, Elephas maximus, can successfully be trained to cooperate in an olfactory discrimination test based on a food-rewarded two-alternative instrumental conditioning procedure. The animals learned the basic principle of the test within only 60 trials and readily mastered intramodal stimulus transfer tasks. Further, they were capable of distinguishing between structurally related odor stimuli and remembered the reward value of previously learned odor stimuli after 2, 4, 8, and 16 weeks of recess without any signs of forgetting. The precision and consistency of the elephants' performance in tests of odor discrimination ability and long-term odor memory demonstrate the suitability of this method for assessing olfactory function in this proboscid species. An across-species comparison of several measures of olfactory learning capabilities such as speed of initial task acquisition and ability to master intramodal stimulus transfer tasks shows that Asian elephants are at least as good in their performance as mice, rats, and dogs, and clearly superior to nonhuman primates and fur seals. The results support the notion that Asian elephants may use olfactory cues for social communication and food selection and that the sense of smell may play an important role in the control of their behavior.
Collapse
|