Photoperiod and Temperature Affect Reproductive and Nonreproductive Functions in Male Prairie Voles (Microtus Ochrogaster)11

Abstract

Adult male prairie voles (Microtus ochrogaster) were housed for 10 wk and exposed to long (16L:8D) or short (8L:16D) photoperiods at 21 degrees or 5 degrees C. Maintenance in short day lengths reduced testicular, epididymal, and seminal vesicle mass and also significantly depressed spermatogenic activity. Cold ambient temperature further suppressed gonadal size in voles exposed to short days. Several pelage characteristics were affected by photoperiod, but not by temperature. Increased fur density, fur depth, and length of guard hair and underhair were observed in voles exposed to short days. Intrascapular brown fat and gonadal fat pad mass as well as body mass were significantly less in voles housed in cold temperatures than in voles exposed to warm ambient temperatures; photoperiod did not affect these parameters. Approximately 30% of the male voles exposed to short days maintained their reproductive systems, yet they clearly processed photoperiodic information; all short-day males, regardless of reproductive condition, had comparable winter pelage development. Our results suggest that in prairie voles, photoperiod may be a predictive cue for reproductive function in nature; however, it appears that pelage development is a more obligatory response to photoperiod than is reproduction.

Phodopus campbelli detect reduced photoperiod during development but, unlike Phodopus sungorus, retain functional reproductive physiology

“…Thus, reproductive development in spite of detection of reduced photoperiod, might reflect an interaction between stimulatory and inhibitory environmental cues that have greater salience for P. campbelli than for P. sungorus (e.g. Duncan et al 1985, Masuda & Oishi 1988, Nelson et al 1989.…”

Photoperiod Affects the Gonadotropin- Releasing Hormone Neuronal System of Male Prairie Voles <bolditalic>(Microtus ochrogaster)</bolditalic>

“…Paired testes weights were used to separate short-day animals into responders (R) and nonresponders (NR). Animals with testes weights >500 mg were considered nonresponders (n = 7), while voles with testes weights <300 mg were considered responders (n = 7) [19]. Animals with intermediate paired testes weights were not used in the study.…”

“…Prairie voles are seasonally-breeding arvicoline rodents inhabiting much of the midwestern United States. In common with other arvicoline species, during the short days of winter, or when maintained on artificial short day lengths in the laboratory, a majority of male prairie voles exhibit dramatic reductions in circulating gonadotropin and testosterone concentrations, leading to regression of the reproductive system [15, 16, 17, 18, 19, 20]. However, 20–40% of male voles do not undergo reproductive regression in response to short days in most populations [21].…”

Seasonal changes in reproductive development in male spiny mice (Acomys spinosissimus) from South Africa

“…This rainfall leads to an increase in primary productivity and consequently higher food quantity and quality compared to the dry season and this relationship of rainfall and increased primary productivity has been suggested to be the ultimate factor regulating reproduction in such regions (Delany, 1972;Neal, 1986;Perrin, 1986). In contrast, ambient temperature appears to be a more important factor at temperate latitudes (Bronson, 1985;Nelson et al, 1989). Many mammals use the seasonally changing day-night cycle as a proximate cue to herald reproductive activation, which is especially effective in highly predictable environments (Bradshaw and Holzapfel, 2007).…”