Photoperiodicity and circannual levels of LH, FSH, and testosterone in normal and castrated male, white-tailed deer

Abstract

To establish the relation between photoperiodicity and the levels of LH, FSH, and testosterone (T) in plasma, three intact and three castrated adult male white-tailed deer were sampled once a month for 2-3 years. The rang of average LH levels in controls varied between 0.8 and 2.0 ng/mL; the levels in castrates were considerably higher, 3.4 to 8.9 ng/mL. Average levels of FSH varied in controls between 25 and 112 ng/mL and in castrates between 141 and 240 ng/mL. A significant correlation between the seasonal time course of LH and FSH was found in castrated, but not in intact bucks. In castrates both gonadotropins exhibit two major elevations coinciding with spring and fall equinoxes in March and September. The seasonal time course of FSH in castrates correlates highly with seasonal levels of FSH in controls. However, the time course of the LH curve in controls is substantially different from the curve in castrates, presumably owing to feedback mechanisms. A possible role of testicular estradiol in this feedback is discussed. In controls, peak T levels are reached in December, i.e., 3 months after maximum levels of FSH and 5 months after peak levels of LH were detected. It appears that male deer undergo two periods of reproductive stimulation (one in the spring, the other in the fall). However, the organism responds with the full range of gonadal and behavioral mechanisms leading to the initiation of the rut only during the fall.

Circannual inter-relationships among reproductive hormones, gross morphometry, behaviour, ejaculate characteristics and testicular histology in Eld's deer stags (Cervus eldi thamin)

“…4b) (Lincoln and Kay, 1979 (Sanford et al, 1984) and impala (Brown et al, 1991b). Overall, our data were similar to observations of white-tailed deer (Bubenik et al, 1982), roe deer (Sempéré and Lacroix, 1982) and red deer (Suttie et al, 1984), supporting the concept that LH is critical for initiating testicular steroidogenic activity, whereas FSH and testosterone are important for supporting spermatogenesis later, during the peak of the circannual testicular cycle.…”

“…Eld's deer were also similar to white-tailed deer (Mirarchi et al, 1978;Bubenik et al, 1982) Prolactin secretory patterns in Eld's deer were directly related to daylength and maximum concentrations were observed during long days and minimal concentrations during short days. Red deer (Kelly et al, 1982), white-tailed deer (Mirarchi et al, 1978;Shulte et al, 1981;, reindeer (Ryg and Jacobson, 1982), roe deer (Schams and Barth, 1982) and rusa deer (van Mourik and Stelmasiak, 1985) exhibit similar temporal patterns with maximum prolactin secretion occurring about the time of the summer solstice, regardless of latitude (Fig.…”

“…Knowledge about seasonal reproduction in male ungulates has been largely derived from studies of domestic rams and temper¬ ate deer species. There are 40 cervine species in the family Cervidae, but endocrine control of the annual testicular cycle has been studied only in white-tailed deer (Odocoileus virginianus, McMillin et al, 1974;Mirarchi et al, 1978;Bubenik et al, 1982), black-tailed deer (Odocoileus hemionus columbianus, West and exposed to wide seasonal oscillations in photoperiod in their native habitat, they are subjected to an extended rainy season (mid-May to mid-October) (Wemmer and Grodinsky, 1988 Grodinsky, 1988) and India (25°N latitude, Desai and Malhotra, 1970 (Lincoln, 1985;Loudon and Brinklow, 1992 (Brown et al, 1991a (Brown et al, 1987). Serial (Brown and Chakraborty, 1991 (Brown et al, 1992 (Chenoweth and Ball, 1980 (Howard et al, 1986 (Howard et al, 1986 Behavioural aggression scores were lowest throughout the summer (July-September), but increased steadily thereafter until all males displayed peak and sustained aggressive behaviour in spring (March-May) (Fig.…”

Morfometria corpórea, características do sêmen, proteínas seminais e testosterona em cervos Cervus unicolor, em cativeiro

“…Uma elevação sazonal da concentração de testosterona foi observada na primavera em cervos Columbian black-tailed, Red deer e Follon deer (West e Nordan, 1976;Rolf e Fischer, 1990). Em cervos White-tailed deer, a máxima concentração de testosterona não foi necessária para o processo da espermatogênese, mas foi essencial para a manifestação do comportamento reprodutivo (Bubenik et al, 1982).…”

Seasonal changes in plasma concentrations of gonadotropins and in the responsiveness of the pituitary and testis to GnRH in a desert rodent, the sand rat (Psammomys obesus)

“…Because of the very low plasma values at 0 min, the purification on celite column was omitted (Khammar and Brudieux, 1987 Schanbacher and Lunstra, 1976;Ortavant and Loir, 1980) and in wild animals (vole: Charlton et al, 1983;mongoose: Soares and Hoffmann, 1981;squirrel: Barnes, 1986; fox and badger: Maurel, 1981;Audy et al, 1985;deer: Lincoln and Kay, 1979;Bubenik et al, 1982). In most cases, seasonal changes in plasma LH levels parallelled those of plasma testosterone concentrations.…”