{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,3]],"date-time":"2026-05-03T06:42:02Z","timestamp":1777790522118,"version":"3.51.4"},"reference-count":19,"publisher":"SAGE Publications","issue":"2","license":[{"start":{"date-parts":[[1990,6,1]],"date-time":"1990-06-01T00:00:00Z","timestamp":644198400000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.sagepub.com\/page\/policies\/text-and-data-mining-license"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["J Biol Rhythms"],"published-print":{"date-parts":[[1990,6]]},"abstract":"<jats:p>\n                    The illuminance threshold for maintenance of testicular function was found to be considerably higher in Syrian hamsters kept in continuous light (LL) than in hamsters on long-day (14-hr) photoperiods (LD 14:10), or in a similar-length skeleton photoperiod (LDSK); the threshold lay between 3 and 30 lux in LL and at approximately 0.3 lux in LD 14:10 or LDSK. The threshold for testicular maintenance in LL was related to the capacity of LL to suppress nocturnal melatonin secretion: 400 lux totally suppressed, 30 or 3 lux partially suppressed, and 0.3 lux failed to suppress melatonin secretion. Hamsters in the LD and LDSK groups, whose locomotion was entrained into a pattern characteristic of long-day exposure, maintained full testicular function; those whose locomotion free-ran or assumed a pattern of entrainment characteristic of short-day exposure underwent testicular regression. These results suggest that light signals entrain the circadian rhythms of locomotion and melatonin secretion in a similar manner, and that LL is less effective than LD or LDSK in shortening the duration of melatonin secretion. For hamsters in LL, a direct relationship was seen between the free-running period (\u03c4) of locomotion and log\n                    <jats:sub>10<\/jats:sub>\n                    illuminance at 0.3, 3.0, and 30 lux, but \u03c4 at 400 lux was no longer than \u03c4 at 30 lux. Splitting of locomotion did not occur at 0.3 or 3.0 lux, and occurred in 43% and 62% of hamsters in 30 and 400 lux, respectively.\n                  <\/jats:p>","DOI":"10.1177\/074873049000500203","type":"journal-article","created":{"date-parts":[[2007,3,11]],"date-time":"2007-03-11T03:24:21Z","timestamp":1173583461000},"page":"107-118","source":"Crossref","is-referenced-by-count":2,"title":["Illuminance Threshold for Maintenance of Testes in Syrian Hamsters (Mesocricetus auratus) Is Higher in Continuous Light than in Long Photoperiods"],"prefix":"10.1177","volume":"5","author":[{"given":"Charles E.","family":"McCormack","sequence":"first","affiliation":[{"name":"Department of Physiology and Biophysics, University of Health Sciences\/ The Chicago Medical School, North Chicago, Illinois 60064"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"179","published-online":{"date-parts":[[1990,6,1]]},"reference":[{"key":"atypb1","doi-asserted-by":"publisher","DOI":"10.1111\/j.1600-079X.1984.tb00202.x"},{"key":"atypb2","doi-asserted-by":"publisher","DOI":"10.1016\/0006-8993(82)90931-3"},{"key":"atypb3","first-page":"2339","volume":"35","author":"Elliott, J.A.","year":"1976","journal-title":"Fed. Proc."},{"key":"atypb4","unstructured":"Elliott, J.A. (1981) Circadian rhythms, entrainment and photoperiodism in the Syrian hamster. In Biological Clocks in Seasonal Reproductive Cycles, B. K. Follett and D. E. Follett, eds., pp. 203-217, Wright, Bristol, England."},{"key":"atypb5","first-page":"R296","volume":"247","author":"Ferraro, J.S.","year":"1984","journal-title":"Am. J. Physiol."},{"key":"atypb6","doi-asserted-by":"publisher","DOI":"10.1095\/biolreprod33.1.93"},{"key":"atypb7","unstructured":"Goldman, B.D. (1983) The physiology of melatonin in mammals. In Pineal Research Reviews, Vol. 1, R. J. Reiter, ed., pp. 145-182, Alan R. Liss , New York."},{"key":"atypb8","doi-asserted-by":"publisher","DOI":"10.1095\/biolreprod13.5.576"},{"key":"atypb9","doi-asserted-by":"publisher","DOI":"10.1159\/000123226"},{"issue":"1","key":"atypb10","first-page":"148","volume":"36","author":"McCormack, C.E.","year":"1987","journal-title":"Biol. Reprod."},{"key":"atypb11","first-page":"865","volume":"13","author":"McCormack, C.E.","year":"1987","journal-title":"Soc. Neurosci. Abstr."},{"key":"atypb12","doi-asserted-by":"publisher","DOI":"10.1007\/978-1-4757-0815-8_14"},{"key":"atypb13","doi-asserted-by":"publisher","DOI":"10.1016\/0031-9384(82)90236-0"},{"key":"atypb14","doi-asserted-by":"publisher","DOI":"10.1210\/endo-98-2-482"},{"key":"atypb15","unstructured":"Steel, F.G.D., and J.H. Torrie (1960) Analysis of variance I: The one-way classification . In Principles and Procedures of Statistics, pp. 99-131, McGraw-Hill , New York."},{"key":"atypb16","doi-asserted-by":"publisher","DOI":"10.1210\/endo-104-2-385"},{"key":"atypb17","doi-asserted-by":"publisher","DOI":"10.1210\/endo-107-5-1525"},{"key":"atypb18","doi-asserted-by":"publisher","DOI":"10.1126\/science.3881822"},{"key":"atypb19","doi-asserted-by":"publisher","DOI":"10.1177\/074873048700200404"}],"container-title":["Journal of Biological Rhythms"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/journals.sagepub.com\/doi\/pdf\/10.1177\/074873049000500203","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/journals.sagepub.com\/doi\/pdf\/10.1177\/074873049000500203","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,4,29]],"date-time":"2026-04-29T20:00:38Z","timestamp":1777492838000},"score":1,"resource":{"primary":{"URL":"https:\/\/journals.sagepub.com\/doi\/10.1177\/074873049000500203"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1990,6]]},"references-count":19,"journal-issue":{"issue":"2","published-print":{"date-parts":[[1990,6]]}},"alternative-id":["10.1177\/074873049000500203"],"URL":"https:\/\/doi.org\/10.1177\/074873049000500203","relation":{},"ISSN":["0748-7304","1552-4531"],"issn-type":[{"value":"0748-7304","type":"print"},{"value":"1552-4531","type":"electronic"}],"subject":[],"published":{"date-parts":[[1990,6]]}}}