Photoperiodic regulation of testis function in rats: mediation by a circadian mechanism

Journal Article · Sat May 01 04:00:00 EDT 1982 · Biol. Reprod.; (United States)

DOI:https://doi.org/10.1095/biolreprod26.2.329· OSTI ID:7090430

Nelson, R J; Bamat, M K; Zucker, I

Laboratory rats traditionally are classified as nonphotoperiodic because variations in daylength have little or no effect on their gonadal function. After olfactory bulbectomy, however, rats show clear evidence of photoperiodic regulation of the gonads. The present study demonstrates, by means of resonance experiments, that the testicular response to daylength in rats is mediated by a circadian photoperiodic time measurement system similar to that of photoperiodic rodents. Olfactory-bulbectomized rats were maintained in fixed photoperiods in which a 6 h light period was coupled with dark periods of 18, 30, 42, or 54 h; a fifth group was maintained in a 45L:10D photoperiod. Rats from the 6L:30D, 6L:54D and 14L:10D photoperiods had testes and seminal vesicle weights, plasma testosterone titers and spermatogenesis indices indicative of functional reproductive status. Rats exposed to the 6L:18D and 6L:42D photoperiods had reduced testicular and seminal vesicle weights, lower testosterone levels and reduced spermatogenesis. Researchers hypothesize that photo- and nonphotoperiodic rodent species use similar mechanisms for distinguishing long from short photoperiods, but differ in the extent to which discrimination of short daylengths is transduced into altered gonadal activity.

• Research Organization: Department of Psychology, University of California, Berkeley
• OSTI ID: 7090430
• Journal Information: Biol. Reprod.; (United States), Journal Name: Biol. Reprod.; (United States) Vol. 26:2; ISSN BIREB
• Country of Publication: United States
• Language: English

Related Subjects

550100* -- Behavioral Biology
551000 -- Physiological Systems
59 BASIC BIOLOGICAL SCIENCES
ANIMALS
BEHAVIOR
BIOLOGICAL EFFECTS
BODY
COMPARATIVE EVALUATIONS
DAILY VARIATIONS
ELECTROMAGNETIC RADIATION
GONADS
MALE GENITALS
MAMMALS
ORGANS
PHOTOPERIOD
PHYSIOLOGY
RADIATIONS
RATS
REPRODUCTION
RODENTS
TESTES
TIME DEPENDENCE
VARIATIONS
VERTEBRATES
VISIBLE RADIATION