Seasonal variation in plasma testosterone, luteinizing hormone concentrations and LH-RH responsiveness in mature, male rusa deer (Cervus rusa timorensis)

The effect of ACTH on the GnRH-induced release of LH and testosterone in male white-tailed deer

“…Similar pattern was found in the Texas white-tailed deer yearlings where peak LH levels were detected in the summer and fall. Testosterone levels reflect obvious seasonal pattern, well established in boreal cervids [2,24,29]. However, unlike in more northern locations, in white-tailed yearlings of southern Texas rutting season appears to culminate in winter and not in the fall.…”

“…GnRH has been also used to study seasonal variation of pituitary and gonadal activity in male cervids. Several species of deer were investigated, such as white-tailed deer [3,8], red deer [17,26], rusa deer [29], and axis deer [9].…”

The effect of ACTH on the GnRH-induced release of LH and testosterone in male white-tailed deer

“…Similar pattern was found in the Texas white-tailed deer yearlings where peak LH levels were detected in the summer and fall. Testosterone levels reflect obvious seasonal pattern, well established in boreal cervids [2,24,29]. However, unlike in more northern locations, in white-tailed yearlings of southern Texas rutting season appears to culminate in winter and not in the fall.…”

“…GnRH has been also used to study seasonal variation of pituitary and gonadal activity in male cervids. Several species of deer were investigated, such as white-tailed deer [3,8], red deer [17,26], rusa deer [29], and axis deer [9].…”

The effect of latitude on the seasonal pattern of reproductive hormones in the male white-tailed deer

“…Another tropical deer, (Cervus rusa timorensis) investigated in southern Australia, exhibited a clear seasonality of reproduction (Van Mourik et al, 1986). However, since the parturition period of this cervid is confined to the late fall, it appears that this deer is similar to the axis deer of southern Texas in that climatic selection for the most optical forage conditions and not the photoperiodicity has been the determining factor of the reproducive synchronization (Branan and Marchington, 1987).…”

“…In contrast, the reproductive pattern of tropical cervids is basically aseasonal (Branan and Marchington, 1987;Blouch, 1987). As the circannual levels of reproductive hormones of tropical species have been investigated only in populations transplanted to temperate zones (Van Mourik et al 1986;Loudon and Curlewis, 1988), it is rather difficult to establish the true effect of latitude on the regulation of reproduction. In addition, comparing reproductive patterns of different cervid species may lead to wrong conclusions.…”

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)

“…Their annual variations in the B6ni-Abbbs area have been previously described (Khammar and Brudieux, 1984). The implication of photoperiod is most likely because of the onset of pituitary activity took place after the summer solstice and the photoperiodic regulation of neuroendocrine gonadal activity is well known (Turek and Campbell, 1979) (Lincoln, 1977), the deer (Lincoln and Kay, 1979;Plotka et al, 1984;Van Mourik et al, 1986) (Khammar and Brudieux, 1989). The present results on release of testosterone in response to GnRH strengthen the above conclusion.…”

The effect of ACTH on the GnRH-induced release of LH and testosterone in male white-tailed deer

“…Similar pattern was found in the Texas white-tailed deer yearlings where peak LH levels were detected in the summer and fall. Testosterone levels reflect obvious seasonal pattern, well established in boreal cervids [2,24,29]. However, unlike in more northern locations, in white-tailed yearlings of southern Texas rutting season appears to culminate in winter and not in the fall.…”

“…GnRH has been also used to study seasonal variation of pituitary and gonadal activity in male cervids. Several species of deer were investigated, such as white-tailed deer [3,8], red deer [17,26], rusa deer [29], and axis deer [9].…”

The effect of latitude on the seasonal pattern of reproductive hormones in the male white-tailed deer

“…Another tropical deer, (Cervus rusa timorensis) investigated in southern Australia, exhibited a clear seasonality of reproduction (Van Mourik et al, 1986). However, since the parturition period of this cervid is confined to the late fall, it appears that this deer is similar to the axis deer of southern Texas in that climatic selection for the most optical forage conditions and not the photoperiodicity has been the determining factor of the reproducive synchronization (Branan and Marchington, 1987).…”

“…In contrast, the reproductive pattern of tropical cervids is basically aseasonal (Branan and Marchington, 1987;Blouch, 1987). As the circannual levels of reproductive hormones of tropical species have been investigated only in populations transplanted to temperate zones (Van Mourik et al 1986;Loudon and Curlewis, 1988), it is rather difficult to establish the true effect of latitude on the regulation of reproduction. In addition, comparing reproductive patterns of different cervid species may lead to wrong conclusions.…”

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)

“…Their annual variations in the B6ni-Abbbs area have been previously described (Khammar and Brudieux, 1984). The implication of photoperiod is most likely because of the onset of pituitary activity took place after the summer solstice and the photoperiodic regulation of neuroendocrine gonadal activity is well known (Turek and Campbell, 1979) (Lincoln, 1977), the deer (Lincoln and Kay, 1979;Plotka et al, 1984;Van Mourik et al, 1986) (Khammar and Brudieux, 1989). The present results on release of testosterone in response to GnRH strengthen the above conclusion.…”

The effect of ACTH on the GnRH-induced release of LH and testosterone in male white-tailed deer

“…Similar pattern was found in the Texas white-tailed deer yearlings where peak LH levels were detected in the summer and fall. Testosterone levels reflect obvious seasonal pattern, well established in boreal cervids [2,24,29]. However, unlike in more northern locations, in white-tailed yearlings of southern Texas rutting season appears to culminate in winter and not in the fall.…”

“…GnRH has been also used to study seasonal variation of pituitary and gonadal activity in male cervids. Several species of deer were investigated, such as white-tailed deer [3,8], red deer [17,26], rusa deer [29], and axis deer [9].…”

The effect of latitude on the seasonal pattern of reproductive hormones in the male white-tailed deer

“…Another tropical deer, (Cervus rusa timorensis) investigated in southern Australia, exhibited a clear seasonality of reproduction (Van Mourik et al, 1986). However, since the parturition period of this cervid is confined to the late fall, it appears that this deer is similar to the axis deer of southern Texas in that climatic selection for the most optical forage conditions and not the photoperiodicity has been the determining factor of the reproducive synchronization (Branan and Marchington, 1987).…”

“…In contrast, the reproductive pattern of tropical cervids is basically aseasonal (Branan and Marchington, 1987;Blouch, 1987). As the circannual levels of reproductive hormones of tropical species have been investigated only in populations transplanted to temperate zones (Van Mourik et al 1986;Loudon and Curlewis, 1988), it is rather difficult to establish the true effect of latitude on the regulation of reproduction. In addition, comparing reproductive patterns of different cervid species may lead to wrong conclusions.…”

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)

“…Their annual variations in the B6ni-Abbbs area have been previously described (Khammar and Brudieux, 1984). The implication of photoperiod is most likely because of the onset of pituitary activity took place after the summer solstice and the photoperiodic regulation of neuroendocrine gonadal activity is well known (Turek and Campbell, 1979) (Lincoln, 1977), the deer (Lincoln and Kay, 1979;Plotka et al, 1984;Van Mourik et al, 1986) (Khammar and Brudieux, 1989). The present results on release of testosterone in response to GnRH strengthen the above conclusion.…”