Register      Login
Reproduction, Fertility and Development Reproduction, Fertility and Development Society
Vertebrate reproductive science and technology
RESEARCH ARTICLE

Identification and immunolocalisation of melatonin MT1 and MT2 receptors in Rasa Aragonesa ram spermatozoa

Adriana Casao A C , Margarita Gallego B , José Alfonso Abecia A , Fernando Forcada A , Rosaura Pérez-Pé A , Teresa Muiño-Blanco A and José Álvaro Cebrián-Pérez A
+ Author Affiliations
- Author Affiliations

A Grupo Biología y Fisiología de la Reproducción, Instituto de Investigación de Ciencias Ambientales de Aragón (IUCA), Facultad de Veterinaria, Universidad de Zaragoza, C/Miguel Servet 177, 500013, Zaragoza, Spain.

B Departamento de Patología Animal, Facultad de Veterinaria, Universidad de Zaragoza, C/Miguel Servet 177, 500013, Zaragoza, Spain.

C Corresponding author. Email: adriana@unizar.es

Reproduction, Fertility and Development 24(7) 953-961 https://doi.org/10.1071/RD11242
Submitted: 21 September 2011  Accepted: 26 January 2012   Published: 20 March 2012

Abstract

The reproductive seasonality of sheep suggests that melatonin receptors may be present in ram spermatozoa. The present study confirms the presence of melatonin MT1 and MT2 receptors. The MT1 receptor was detected using immunocytochemistry, with four sperm subpopulations identified based on the following labelling patterns: (1) one small subpopulation with labelling over the entire head and tail; (2) one of two main subpopulations that exhibited reactivity at the equatorial, post-acrosomal, neck and tail regions; (3) another main subpopulation with equatorial and tail labelling only; and (4) a subpopulation in which staining was detected only in the tail. Immunocytochemistry revealed the presence of the melatonin MT2 receptor, with intense staining on the acrosome, post-acrosomal region and neck and tail regions of all cells, but not in the equatorial region. Western blot identification of ram protein extracts revealed a 39-kDa band compatible with both MT1 and MT2 receptors, a 75-kDa band compatible with MT1/MT2 heterodimerisation, a 32-kDa band compatible with MT1 receptor activation and a double band of 45–55 kDa that is compatible with MT2 receptor homodimerisation or heterodimerisation with other G-proteins. In conclusion, we provide evidence of the presence of MT1 and MT2 receptors in ram spermatozoa, although the biochemical pathway triggered by these receptors and their function in terms of fertility remains to be elucidated.

Additional keywords: immunocytochemistry, immunofluorescence, western blot.


References

Almog, T., Lazar, S., Reiss, N., Etkovitz, N., Milch, E., Rahamim, N., Dobkin-Bekman, M., Rotem, R., Kalina, M., Ramon, J., Raziel, A., Brietbart, H., Seger, R., and Naor, Z. (2008). Identification of extracellular signal-regulated kinase 1/2 and p38 MAPK as regulators of human sperm motility and acrosome reaction and as predictors of poor spermatozoan quality. J. Biol. Chem. 283, 14 479–14 489.
Identification of extracellular signal-regulated kinase 1/2 and p38 MAPK as regulators of human sperm motility and acrosome reaction and as predictors of poor spermatozoan quality.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1cXlvFyjsL4%3D&md5=6471ca661684ac28b94a8bded13bdfafCAS |

Ayoub, M. A., Levoye, A., Delagrange, P., and Jockers, R. (2004). Preferential formation of MT1/MT2 melatonin receptor heterodimers with distinct ligand interaction properties compared with MT2 homodimers. Mol. Pharmacol. 66, 312–321.
Preferential formation of MT1/MT2 melatonin receptor heterodimers with distinct ligand interaction properties compared with MT2 homodimers.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2cXmtVyksr8%3D&md5=44d609b51d2ab065178b16268ba6a1e7CAS | 15266022PubMed |

Balao da Silva, C. M., Macías-García, B., Miró-Morán, A., González-Fernández, L., Morillo-Rodriguez, A., Ortega-Ferrusola, C., Gallardo-Bolaños, J. M., Stilwell, G., Tapia, J. A., and Peña, F. J. (2011). Melatonin reduces lipid peroxidation and apoptotic-like changes in stallion spermatozoa. J. Pineal Res. 51, 172–179.
Melatonin reduces lipid peroxidation and apoptotic-like changes in stallion spermatozoa.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3MXhtVOlurvL&md5=27c437c7d944b373135297f16ad41091CAS |

Breitbart, H., Lax, J., Rotem, R., and Naor, Z. (1992). Role of protein-kinase-C in the acrosome reaction of mammalian spermatozoa. Biochem. J. 281, 473–476.
| 1:CAS:528:DyaK38XjvVOiug%3D%3D&md5=78df8f95e9676706a5f8d95d6f45df4aCAS | 1736894PubMed |

Casao, A., Cebrian, I., Asumpcao, M., Perez-Pe, R., Abecia, J., Forcada, F., Cebrian-Perez, J., and Muino-Blanco, T. (2010a). Seasonal variations of melatonin in ram seminal plasma are correlated to those of testosterone and antioxidant enzymes. Reprod. Biol. Endocrinol. 8, .
Seasonal variations of melatonin in ram seminal plasma are correlated to those of testosterone and antioxidant enzymes.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3cXotV2jsr8%3D&md5=8c0b2b9c65f37fbb985d3be330bb4979CAS | 20540737PubMed |

Casao, A., Mendoza, N., Pérez-Pé, R., Grasa, A., Abecia, J. A., Forcada, F., Cebrián-Pérez, J. A., and Muino-Blanco, T. (2010b). Melatonin prevents capacitation and apoptotic-like changes of ram spermatozoa and increases fertility rate. J. Pineal Res. 48, 39–46.
Melatonin prevents capacitation and apoptotic-like changes of ram spermatozoa and increases fertility rate.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1MXhs1WhtLzL&md5=075d8adf73ff8d6badf01ec463fa4cc7CAS | 19919602PubMed |

Casao, A., Vega, S., Palacín, I., Pérez-Pe, R., Laviña, A., Quintín, F. J., Sevilla, E., Abecia, J. A., Cebrián-Pérez, J. A., Forcada, F., and Muiño-Blanco, T. (2010c). Effects of melatonin implants during non-breeding season on sperm motility and reproductive parameters in Rasa Aragonesa rams. Reprod. Domest. Anim. 45, 425–432.
Effects of melatonin implants during non-breeding season on sperm motility and reproductive parameters in Rasa Aragonesa rams.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3cXnvFGrtLc%3D&md5=6631e5ab48ec4b7a5def231187470881CAS | 18954380PubMed |

Chan, A. S. L., Lai, F. P. L., Lo, R. K. H., Voyno-Yasenetskaya, T. A., Stanbridge, E. J., and Wong, Y. H. (2002). Melatonin MT1 and MT2 receptors stimulate c-Jun N-terminal kinase via pertussis toxin-sensitive and -insensitive G proteins. Cell Signal. 14, 249–257.
Melatonin MT1 and MT2 receptors stimulate c-Jun N-terminal kinase via pertussis toxin-sensitive and -insensitive G proteins.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD38Xms1GqsQ%3D%3D&md5=02fcd498ecc9ce72509d98552b3cecc5CAS |

Chemineau, P., Malpaux, B., Delgadillo, J. A., Guerin, Y., Ravault, J. P., Thimonier, J., and Pelletier, J. (1992). Control of sheep and goat reproduction: use of light and melatonin. Anim. Reprod. Sci. 30, 157–184.
Control of sheep and goat reproduction: use of light and melatonin.Crossref | GoogleScholarGoogle Scholar |

Cogé, F., Guenin, S. P., Fery, I., Migaud, M., Devavry, S., Slugocki, C., Legros, C., Ouvry, C., Cohen, W., Renault, N., Nosjean, O., Malpaux, B., Delagrange, P., and Boutin, J. A. (2009). The end of a myth: cloning and characterization of the ovine melatonin MT2 receptor. Br. J. Pharmacol. 158, 1248–1262.
The end of a myth: cloning and characterization of the ovine melatonin MT2 receptor.Crossref | GoogleScholarGoogle Scholar | 19814723PubMed |

Colás, C., Grasa, P., Casao, A., Gallego, M., Abecia, J. A., Forcada, F., Cebrián-Pérez, J. A., and Muiño-Blanco, T. (2009). Changes in calmodulin immunocytochemical localization associated with capacitation and acrosomal exocytosis of ram spermatozoa. Theriogenology 71, 789–800.
Changes in calmodulin immunocytochemical localization associated with capacitation and acrosomal exocytosis of ram spermatozoa.Crossref | GoogleScholarGoogle Scholar | 19081128PubMed |

Coyan, K., Kaya, A., Karaca, F., Ataman, M. B., and Yildiz, C. (1998). The effect of melatonin on sperm quality and testicular size of normospermic and pathospermic rams in the anoestrous season. Wien Tierarztl. Monatsschr. 85, 383–388.
| 1:CAS:528:DyaK1cXnsVaqs7o%3D&md5=ce4505a4af786c5c57ee32ee85d2056aCAS |

de Lamirande, E., and O’Flaherty, C. (2008). Sperm activation: role of reactive oxygen species and kinases. Biochim. Biosphys. Acta 1784, 106–115.
Sperm activation: role of reactive oxygen species and kinases.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1cXptlersQ%3D%3D&md5=13c2ba20642f0a2c29072048a8de5605CAS |

Dubocovich, M. L., and Markowska, M. (2005). Functional MT1 and MT2 melatonin receptors in mammals. Endocrine 27, 101–110.
Functional MT1 and MT2 melatonin receptors in mammals.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2MXhtFansLjE&md5=a3bc7fd213e31806d425c214ee5a4539CAS | 16217123PubMed |

Dubocovich, M. L., Rivera-Bermudez, M. A., Gerdin, M. J., and Masana, M. I. (2003). Molecular pharmacology, regulation and function of mammalian melatonin receptors. Front. Biosci. 8, d1093–d1108.
Molecular pharmacology, regulation and function of mammalian melatonin receptors.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD3sXjvVajsLo%3D&md5=dd2511ca857dcd118a6720b445cb6d79CAS | 12957828PubMed |

Dubocovich, M., Delagrange, P., and Olcese, J. (2009). ‘Melatonin Receptors.’ Available at: http://www.iuphar-db.org/DATABASE/FamilyMenuForward?familyId=39 [Verified 31 November 2011].

European Community Commission (1986). Scientific procedure and breeding of animals for use in scientific procedures establishments. In ‘Directive 86/609/EEC.’ (Ed. European Community Commission.) pp. 1–28. (European Community Commission: Brussel.)

Espino, J., Ortiz, Á., Bejarano, I., Lozano, G. M., Monllor, F., García, J. F., Rodríguez, A. B., and Pariente, J. A. (2011). Melatonin protects human spermatozoa from apoptosis via melatonin receptor- and extracellular signal-regulated kinase-mediated pathways. Fertil. Steril. 95, 2290–2296.
Melatonin protects human spermatozoa from apoptosis via melatonin receptor- and extracellular signal-regulated kinase-mediated pathways.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3MXmsFWns7g%3D&md5=332999530e629a8bca3953169e39fcf1CAS | 21497337PubMed |

Frungieri, M. B., Mayerhofer, A., Zitta, K., Pignataro, O. P., Calandra, R. S., and Gonzalez-Calvar, S. I. (2005). Direct effect of melatonin on Syrian hamster testes: melatonin subtype 1a receptors, inhibition of androgen production, and interaction with the local corticotropin-releasing hormone system. Endocrinology 146, 1541–1552.
Direct effect of melatonin on Syrian hamster testes: melatonin subtype 1a receptors, inhibition of androgen production, and interaction with the local corticotropin-releasing hormone system.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2MXitlehur8%3D&md5=c292a869ef3a6c0eda11abc610564d63CAS | 15550508PubMed |

Fujinoki, M. (2008). Melatonin-enhanced hyperactivation of hamster sperm. Reproduction 136, 533–541.
Melatonin-enhanced hyperactivation of hamster sperm.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1cXhsVCjtrnK&md5=18f86fe3f691c410d13206891140998fCAS | 18715981PubMed |

García-López, N., Ollero, M., Muiño-Blanco, T., and Cebrián-Pérez, J. A. (1996). A dextran swim-up procedure for separation of highly motile and viable ram spermatozoa from seminal plasma. Theriogenology 46, 141–151.
A dextran swim-up procedure for separation of highly motile and viable ram spermatozoa from seminal plasma.Crossref | GoogleScholarGoogle Scholar |

Gilman, A. G. (1995). G-Proteins and regulation of adenylyl-cyclase. Biosci. Rep. 15, 65–97.
G-Proteins and regulation of adenylyl-cyclase.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK2MXntFKhtLs%3D&md5=1ac1ffc8390c273cfd2629648ce6e75fCAS | 7579036PubMed |

Hunt, A. E., Al-Ghoul, W. M., Gillette, M. U., and Dubocovich, M. L. (2001). Activation of MT2 melatonin receptors in rat suprachiasmatic nucleus phase advances the circadian clock. Am. J. Physiol. Cell Physiol. 280, C110–C118.
| 1:CAS:528:DC%2BD3MXjtVWmur0%3D&md5=56a8e77398704c9d24d19087b1568aa8CAS | 11121382PubMed |

Ishii, H., Tanaka, N., Kobayashi, M., Kato, M., and Sakuma, Y. (2009). Gene structures, biochemical characterization and distribution of rat melatonin receptors. J. Physiol. Sci. 59, 37–47.
Gene structures, biochemical characterization and distribution of rat melatonin receptors.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1MXktVyksr8%3D&md5=693f5afe0e6935ae7bba1edc3f09d447CAS | 19340560PubMed |

Iwanaga, A., Wang, G., Gantulga, D., Sato, T., Baljinnyam, T., Shimizu, K., Takumi, K., Hayashi, M., Akashi, T., Fuse, H., Sugihara, K., Asano, M., and Yoshioka, K. (2008). Ablation of the scaffold protein JLP causes reduced fertility in male mice. Transgenic Res. 17, 1045–1058.
Ablation of the scaffold protein JLP causes reduced fertility in male mice.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1cXht1yrsr%2FK&md5=95e5e9ea11410c6b2ff6dd92146ba0a8CAS | 18574703PubMed |

Izzo, G., Francesco, A., Ferrara, D., Campitiello, M. R., Serino, I., Minucci, S., and d’Istria, M. (2010). Expression of melatonin (MT1, MT2) and melatonin-related receptors in the adult rat testes and during development. Zygote 18, 257–264.
Expression of melatonin (MT1, MT2) and melatonin-related receptors in the adult rat testes and during development.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3cXosFCktLk%3D&md5=978f5cbd420d26821d4ad2325c772e3eCAS | 20109269PubMed |

Jockers, R., Maurice, P., Boutin, J. A., and Delagrange, P. (2008). Melatonin receptors, heterodimerization, signal transduction and binding sites: what’s new? Br. J. Pharmacol. 154, 1182–1195.
Melatonin receptors, heterodimerization, signal transduction and binding sites: what’s new?Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1cXosVCjtLk%3D&md5=996ef7c885306e0d837100694c003c9dCAS | 18493248PubMed |

Kaya, A., Baspinar, N., Yildiz, C., Kurtoglu, F., Ataman, M. B., and Haliloglu, S. (2000). Influence of melatonin implantation on sperm quality, biochemical composition of the seminal plasma and plasma testosterone levels in rams. Rev. Med. Vet. 151, 1143–1146.
| 1:CAS:528:DC%2BD3MXhtlKmsLg%3D&md5=7e2ace6e5b652fde0b43c6c870f170a5CAS |

Kokolis, N., Theodosiadou, E., Tsantarliotou, M., Rekkas, C., Goulas, P., and Smokovitis, A. (2000). The effect of melatonin implants on blood testosterone and acrosin activity in spermatozoa of the ram. Andrologia 32, 107–114.
The effect of melatonin implants on blood testosterone and acrosin activity in spermatozoa of the ram.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD3cXisVClt7Y%3D&md5=4c82d1ae221cda521195f9ca89b58f8aCAS | 10755193PubMed |

Levoye, A., Dam, J., Ayoub, M. A., Guilllaume, J. L., Couturier, C., Delagrange, P., and Jockers, R. (2006). The orphan GPR50 receptor specifically inhibits MT1 melatonin receptor function through heterodimerization. EMBO J. 25, 3012–3023.
The orphan GPR50 receptor specifically inhibits MT1 melatonin receptor function through heterodimerization.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD28XmvFajtbw%3D&md5=c8308da98c50964164932f0865f29f99CAS | 16778767PubMed |

Lincoln, G. A. (1996). Melatonin regulation of gonadotropin and prolactin secretion in the ram: the dual site hypothesis. Acta Neurobiol. Exp. 56, 846..

Mandiki, S. N. M., Derycke, G., Bister, J. L., and Paquay, R. (1998). Influence of season and age on sexual maturation parameters of Texel, Suffolk and Ile-de-France rams: 1. Testicular size, semen quality and reproductive capacity. Small Rumin. Res. 28, 67–79.
Influence of season and age on sexual maturation parameters of Texel, Suffolk and Ile-de-France rams: 1. Testicular size, semen quality and reproductive capacity.Crossref | GoogleScholarGoogle Scholar |

Morgan, P. J., Lawson, W., Davidson, G., and Howell, H. E. (1989). Melatonin inhibits cyclic-AMP production in cultured ovine par tuberalis cells. J. Mol. Endocrinol. 3, R5–R8.
Melatonin inhibits cyclic-AMP production in cultured ovine par tuberalis cells.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaL1MXlvVyjsr4%3D&md5=8232fdda33990fc45b526a639c50ec8aCAS |

Morgan, P. J., Barrett, P., Howell, H. E., and Helliwell, R. (1994). Melatonin receptors: localization, molecular pharmacology and physiological significance. Neurochem. Int. 24, 101–146.
Melatonin receptors: localization, molecular pharmacology and physiological significance.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK2cXitlKhu7k%3D&md5=b8a1d7959b99b2dfdf538bf77ca39a0eCAS | 8161940PubMed |

Ollero, M., Muino-Blanco, T., Lopez-Perez, M. J., and Cebrian-Perez, J. A. (1996). Viability of ram spermatozoa in relation to the abstinence period and successive ejaculations. Int. J. Androl. 19, 287–292.
Viability of ram spermatozoa in relation to the abstinence period and successive ejaculations.Crossref | GoogleScholarGoogle Scholar | 1:STN:280:DyaK2s7jvVOltQ%3D%3D&md5=60f04c8265ccaa499d8498a379ed87a3CAS | 8985777PubMed |

Ortiz, A., Espino, J., Bejarano, I., Lozano, G. M., Monllor, F., García, J. F., Pariente, J. A., and Rodríguez, A. B. (2011). High endogenous melatonin concentrations enhance sperm quality and short-term in vitro exposure to melatonin improves aspects of sperm motility. J. Pineal Res. 50, 132–139.
| 1:CAS:528:DC%2BC3MXivF2ksrg%3D&md5=1bf38a1a566fcb609ff04908727d4e57CAS | 20964711PubMed |

Pin, J. P., Neubig, R., Bouvier, M., Devi, L., Filizola, M., Javitch, J. A., Lohse, M. J., Milligan, G., Palczewski, K., Parmentier, M., and Spedding, M. (2007). International Union of Basic and Clinical Pharmacology. LXVII. Recommendations for the recognition and nomenclature of G protein-coupled receptor heteromultimers. Pharmacol. Rev. 59, 5–13.
International Union of Basic and Clinical Pharmacology. LXVII. Recommendations for the recognition and nomenclature of G protein-coupled receptor heteromultimers.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2sXkt1WmtLY%3D&md5=27b188e367c613533bb0bbe564ebb63aCAS | 17329545PubMed |

Radogna, F., Paternoster, L., Albertini, M. C., Cerella, C., Accorsi, A., Bucchini, A., Spadoni, G., Diamantini, G., Tarzia, G., De Nicola, M., D’Alessio, M., and Ghibelli, L. (2007). Melatonin antagonizes apoptosis via receptor interaction in U937 monocytic cells. J. Pineal Res. 43, 154–162.
Melatonin antagonizes apoptosis via receptor interaction in U937 monocytic cells.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2sXovFant7Y%3D&md5=79ebdf723a02a496fe9662d920df5245CAS | 17645693PubMed |

Reppert, S. M., Weaver, D. R., and Ebisawa, T. (1994). Cloning and characterization of a mammalian melatonin receptor that mediates reproductive and circadian responses. Neuron 13, 1177–1185.
Cloning and characterization of a mammalian melatonin receptor that mediates reproductive and circadian responses.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK2MXitlylsLY%3D&md5=10f3487dd3a4f54e35b4c3b88236e206CAS | 7946354PubMed |

Rosa, H. J. D., and Bryant, M. J. (2003). Seasonality of reproduction in sheep. Small Rumin. Res. 48, 155–171.
Seasonality of reproduction in sheep.Crossref | GoogleScholarGoogle Scholar |

Solakidi, S., Psarra, A. M., Nikolaropoulos, S., and Sekeris, C. E. (2005). Estrogen receptors alpha and beta (ERalpha and ERbeta) and androgen receptor (AR) in human sperm: localization of ERbeta and AR in mitochondria of the midpiece. Hum. Reprod. 20, 3481–3487.
Estrogen receptors alpha and beta (ERalpha and ERbeta) and androgen receptor (AR) in human sperm: localization of ERbeta and AR in mitochondria of the midpiece.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2MXht1GltrvO&md5=f5e6fa48b18bd47ce257bb597f94548fCAS | 16123086PubMed |

van Vuuren, R. J., Pitout, M. J., van Aswegen, C. H., and Theron, J. J. (1992). Putative melatonin receptor in human spermatozoa. Clin. Biochem. 25, 125–127.
Putative melatonin receptor in human spermatozoa.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK38XlsVeqtLo%3D&md5=af4d7af5b9304b5d5c592f0d4ce58e01CAS | 1320469PubMed |

Webster, J. R., Suttie, J. M., Veenvliet, B. A., Manley, T. R., and Littlejohn, R. P. (1991). Effect of melatonin implants on secretion of luteinizing hormone in intact and castrated rams. J. Reprod. Fertil. 92, 21–31.
Effect of melatonin implants on secretion of luteinizing hormone in intact and castrated rams.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK3MXlsFWjtbw%3D&md5=22cd9fecad61a7237a26b7ba6bead60dCAS | 2056492PubMed |

Williams, L. M., Hannah, L. T., Hastings, M. H., and Maywood, E. S. (1995). Melatonin receptors in the rat brain and pituitary. J. Pineal Res. 19, 173–177.
Melatonin receptors in the rat brain and pituitary.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK28XltFahtg%3D%3D&md5=fe119e1d2f7403d6f735eb1fa53cd2e0CAS | 8789248PubMed |

Witt-Enderby, P. A., Masana, M. I., and Dubocovich, M. L. (1998). Physiological exposure to melatonin supersensitizes the cyclic adenosine 3′,5′-monophosphate-dependent signal transduction cascade in Chinese hamster ovary cells expressing the human mt1 melatonin receptor. Endocrinology 139, 3064–3071.
Physiological exposure to melatonin supersensitizes the cyclic adenosine 3′,5′-monophosphate-dependent signal transduction cascade in Chinese hamster ovary cells expressing the human mt1 melatonin receptor.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK1cXktV2ht7w%3D&md5=663d9176216863ba1da798d1c6b6f6baCAS | 9645677PubMed |

Witt-Enderby, P. A., MacKenzie, R. S., McKeon, R. M., Carroll, E. A., Bordt, S. L., and Melan, M. A. (2000). Melatonin induction of filamentous structures in non-neuronal cells that is dependent on expression of the human mt1 melatonin receptor. Cell Motil. Cytoskel. 46, 28–42.
Melatonin induction of filamentous structures in non-neuronal cells that is dependent on expression of the human mt1 melatonin receptor.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD3cXksFSgsb8%3D&md5=a9182b264923a370064e2669de07e24dCAS |

Witt-Enderby, P. A., Bennett, J., Jarzynka, M. J., Firestine, S., and Melan, M. A. (2003). Melatonin receptors and their regulation: biochemical and structural mechanisms. Life Sci. 72, 2183–2198.
Melatonin receptors and their regulation: biochemical and structural mechanisms.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD3sXhs1CltbY%3D&md5=4b878f64a4125e78ff52185253c51d0fCAS | 12628439PubMed |