* Correspondingauthor Tel.: +33(0)467593703;Fax: 67593795;E-mail:[email protected] Cedex 1, 3. CIRAD-EMVT,Campusinternational de Baillarguet,BP5035,34032Montpellier 2. INRAPRMD,CentredeTours,37380 Nouzilly,France 1. NRConCamel,PB07,Bikaner,334001 over 10kmtoCIRAD-EMVT,Montpellier,whereplasmawas 20th), whendaylightlasted16h.Thesamplesweretransported samples werecollectedinthemonthofMay1997(May19thand for 24h.Samplingatnightwasdoneunderredlight.Theblood h collected invacutainersfromtheexperimentalanimalsevery2 France (Latitude42ûN)wereusedfortheexperiment.Bloodwas farm,"LesMeharées",nearMontpellierintheSouth of Three adultfemaledromedarycamelsbelongingtoaprivate Experimental animals ■ plasma ofdromedarycamelsduringa24hcycle. experiment wasconductedtoestimatethemelatoninlevelsin pattern ofmelatoninincamel( is noinformationavailableintheliteratureaboutsecretory such ashorses(6).However,totheknowledgeofauthorsthere day breederssuchassheep(7)andgoats(2)long participates inthecontrolofreproductivecyclebothshort The melatonin,ahormonesecretedbythepinealgland, March inIsrael(10)andNovembertoAprilmostofArabia(1). extends fromNovembertoMarchinIndia(5),December day lengthstimulatesseasonalreproduction.Thebreedingseason The dromedarycamelsareseasonalbreeders(3,4).Decreasing ■ MATERIALS ANDMETHODS INTRODUCTION France. Dromedary -MelatoninReproduction Key words Camelus dromedarius ( farm animals,thereisanyctohemeralrhythmofmelatoninsecretionincamel she- locatedintheSouthofFrance.Itwasrevealedthat,likeother The melatonin,ahormonesecretedbythepinealgland,wasassayedinthree Summary ( of melatoninsecretionincamel The nyctohemeralrhythm S. Vyas Camelus dromedarius Camelus dromedarius ). Thepresent Retour aumenu 1

J.P. Ravault plasma. plasma wasgood.Thesensitivity of theassaywas5pgmelatonin/ml parallelism betweenastandard-curve andserialdilutionsof camel plasmatreatedwithcharcoal (datanotshown).The plasma. Thereisnodifferencewith astandardcurveobtainedwith Figure 1reportsastandard-curveobtainedwithdaytimecamel ■ the threecamelswereanalyzedinsameassay. were calculatedbylogitcurves(figure1).Allplasmasamplesfrom totally absentforothercompoundstested(9).Theconcentrations was <1%forN-acetylserotoninand6-hydroxy-melatonin curve.The cross-reactivityofthisantibodywithrelatedcompounds plasma totesttheparallelismbetweendilutionandstandard- plasma weretestedagainstastandardcurveindaytimecamel charcoal inordertoremovemelatonin.Serialdilutionsofnight obtained inthemiddleofafternoonoraplasmatreatedwith melatonin/ml) waspreparedusinglowmelatonincamelplasma and thepelletcountedona added for1h.Aftercentrifugation,thesupernatantwasdiscarded 18 hat4ûC,1mlofananti-rabbit melatonin intricinebuffer(15,000cp/min).Afteranincubationof antibody (finaldilution1/400,000)and300µlofiodinated (8). Briefly,to100µlofplasmawereaddedantimelatonin specific radioimmunoassaytechniquepreviouslydescribedinsheep The melatoninplasmaconcentrationwasmeasuredbyadaptinga Melatonin assay RESULTS ANDDISCUSSION ). melatonin wascarriedout. PRMD-INRA, centredeTours,Nouzilly,whereassayfor stored at-20ûC.Thesampleswerethentransportedindryiceto separated bycentrifugationat4ûC3000rpmfor30minand 2 B. Faye γ 3* -counter. Astandard-curve(5-500pg ) P. Chemineau γ -globulin (raisedinsheep)was 2

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■ RESSOURCES ANIMALES communication Revue Élev. Méd. vét. Pays trop., 1997, 50 (3) : 261-263

262 Revue Élev. Méd. vét. Pays trop., 1997, 50 (3) : 261-263 ■ RESSOURCES ANIMALES communication Melatonin secretionincamels letting themusehiscamels. The authorsaregratefultoMr. P. Bartenief,"LesMeharées",for S. Vyaswassponsoredbyagrant fromCIRAD-EMVT,France. Acknowledgements 3-4 to1.5-2years. enhance and/orextendcalvingintervalsindromedarycamelsfrom to periodic controlanditssimulationbymelatoninadministration seasons oftheyearandundercontrolledlighting,touse secretory patternandlevelsofmelatoninincamelsdifferent night asinsheep.Furtherexperimentsarerequiredtostudythe than insheep(8).Secretionofmelatoninoccursthroughoutthe melatonin, butitseemsthatmelatoninconcentrationsarelower pattern (8).Thereareindividualvariationsintheconcentration of secretion ofmelatoninbythepinealglandalsofollowsanyctohemeral The presentexperimentrevealedthat,likeinotherfarmanimals, pg/mlwithsunriseinallthreecamels. declined to5 pg/ml,respectively.Theplasmaconcentrationofmelatonin 50 (figure 2).Peaklevelsinthethreecamelswere50,233and increase inmelatoninconcentrationwasgradualcamel3 pg/mlincamel1)within15minofdarkness,whereasthe (46 reached apeak(233pg/mlincamel2)ornearlevels period ofdarkness.Theplasmaconcentrationintwocamels during theperiodoflight(photophase)andincreasedonlyin The melatoninlevelsinallthreecamelswereverylow(5pg/ml) tions ofplasmacamel( Figure 1 Logit B/B0 -2 -1 0 1 2 3 : standard-curveforplasmacamel( 1/8 ,21-165x R=0,996 Y =3,1271-1,6352x ■ Standard curveforplasmacamel ). 123 1/4 Log/dose 1/2 pure ❍ serial dilutions standard-curve 2 ) andserialdilu- Retour aumenu photo

Solid barsindicate periodsofdarkness. Figure 2 Mel. pg/ml Mel. pg/ml Mel. pg/ml 200 100 300 30 40 20 50 60 10 30 40 20 50 60 10 0 0 0 : nyctohemeralpatternsofmelatonin inplasmacamel. 20 20 022 20 22 22 0 0 0 2 24 2 4 4 Camel 3 Camel 2 Camel 1 68 68 68 Hours Hours Hours

012 10 012 10 012 10

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Sécrétion de mélatonine chez le dromadaire

REFERENCES 5. KHANNA N.D., TANDON S.N., RAI A.K., 1990. Breeding parameters of Indian camel. Indian J. Anim. Sci., 60: 1347-1354. 6. KILMER D.M., SHARP D.C., BERGLUND L.A., GRUBAUGH W., 1. ABDEL RAHIM S.E.A., EL-NAZIER A.E., 1990. Factors affecting camel MCDOWELL K.J., PEEK L.S., 1982. Melatonin rhythms in pony mares reproductive performances in the tropics. In: Proc. Unité de coordination and foals. J. Reprod. Fert. suppl., 32: 303-307. pour l’élevage camelin (Workshop: Is it possible to improve the reproductive performance of the camel?). Maisons-Alfort, France, 7. ORTAVANT R., BOCQUIER F., PELLETIER J., RAVAULT J.P., CIRAD-IEMVT, p. 131-146. THIMONIER J., VOLLANT-NAIL P., 1988. Seasonality of reproduction in sheep and its control by photoperiod. Aust. J. biol. Sci., 41: 69-85. 2. CHEMINEAU P., MALPAUX B., THIERY J.C., VIGIE C., MORELLO H., ZARAZAGA L., PELLETIER J. 1995. The control of seasonality: a 8. RAVAULT J.P., ARENDT J., TOBLER I., 1989. Entrainment of challenge to small ruminant breeding. In: Proc. XXX international melatonin rhythms in rams by symetrical light-dark cycles of different symposium of Societa italiana per il progresso della zootechnica, Milan, period length. Chronobiol. Int., 6: 329-339. , September 11-13, 1995, p. 225-250. 9. TILLET Y., RAVAULT J.P., SELVE C., EVIN G., CASTRO B., DUBOIS M.P., 3. CHEN B.X., YUEN Z.X., 1984. Reproductive pattern of the Bactrian 1986. Condition d’utilisation d’anticorps spécifiques pour la visualisation camel. In: Cockrill W.R. ed., The camelid: an all purpose animal, vol. 1. immunohistochimique de la sérotonine et de la mélatonine dans la Uppsala, , Scandinavian Institute of African Studies, p. 364-396. glande pineale du mouton. C.R. Acad. Ser. III Sci. Vie, 303 : 77-82. 4. JOSHI C.K., VYAS K.K., PAREEK P.K., 1978. Studies on oestrus cycle 10. YAGIL R., 1985. The desert camel. Comparative physiology. in Bikaneri she camel. Indian J. Anim. Sci., 48: 141-145. Comparative nutrition, vol. 5. Basel, , Karger. Reçu le 3.9.97, accepté le 4.12.97

Résumé Resumen

Vyas S., Ravault J.P., Faye B., Chemineau P. Rythme nycthé- Vyas S., Ravault J.P., Faye B., Chemineau P. Ritmo nictemeral méral de la sécrétion de mélatonine chez le dromadaire de la secreción de melatonina en el camello (Camelus drome- (Camelus dromedarius) darius)

La mélatonine, une hormone secrétée par la glande pinéale, a Se administró melatonina, hormona secretada por la glándula été dosée sur trois chamelles vivant dans le Sud de la France. pineal, a tres hembras camellos en el Sur de Francia. Al igual Comme pour les autres espèces domestiques, les résultats que para otras especies domésticas, los resultados demues- montrent qu’il existe un rythme nycthéméral de la sécrétion tran la existencia de un ritmo nictemeral de la secreción de de cette hormone chez le dromadaire (Camelus dromedarius). esta hormona en el dromedario (Camelus dromedarius).

Mots-clés : Dromadaire - Mélatonine - Reproduction - France. Palabras clave: Dromedario - Melatonina - Reproducción - Francia. Revue Élev. Méd. vét. Pays trop., 1997, 50 (3) : 261-263 263