Seasonal endocrine cycles in the European hedgehog, Erinaceus europaeus

Fowler, Paul A.

doi:10.1530/jrf.0.0840259

“…In non-experimental hedgehogs [Fowler, 1988b], plasma melatonin was elevated between November and February at photoperiods shorter than 10L:14D, which were suggested by Fowler [ 1988131 as important in regulating their endogenous cycles. The characteristic February/March peak in plasma testosterone concentrations occurs while melatonin levels are falling.…”

Section: Discussionmentioning

confidence: 93%

“…How the constant melatonin signal is read by melatoninimplanted hedgehogs is important, particularly in view of the seasonal changes in daytime plasma melatonin levels in this species [Fowler, 1988bI. The close correlation between plasma testosterone and rate of change of photoperiod in non-experimental hedgehogs [Fowler, 1988b], in all months except July, may be relevant to differences in sexual reactivation in males implanted in May or September compared to those implanted in August. Although hedgehogs transferred to short photoperiod at the end of summer do not show a change in the timing of sexual reactivation [Saboureau, 1981 1, the present study suggests that such a transfer during May or September would have an effect.…”

Section: Discussionmentioning

confidence: 99%

“…Blood was centrifuged and the plasma stored at -25°C in 1 ml aliquots within 1 h of collection. Plasma testosterone [Fowler and Racey, 19871 and melatonin [Fowler, 1988b] were assayed using previously described double-antibody radioimmunoassays. Plasma thyroxin was measured using a single-antibody radioimmunoassay [Fowler, 1988bl.…”

Section: Blood Sampling and Hormone Assaysmentioning

confidence: 99%

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Retracted: Effect of Melatonin Administration and Long Day‐Length on Endocrine Cycles in the Hedgehog Erinaceus europaeus

Fowler¹,

Racey²

1990

Journal of Pineal Research

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The effects of exogenous melatonin (subcutaneous implants containing 0.031 +/- 0.006 mg/gm body mass melatonin) or long photoperiod (18L:6D) on wild-caught adult male hedgehogs were studied. Hedgehogs were implanted with melatonin-filled or empty capsules in May, August, or September, or maintained under long photoperiod from August. Blood samples collected at monthly intervals were assayed for testosterone, melatonin, and thyroxin. Melatonin-filled capsules elevated plasma melatonin concentrations for 4-6 months. Although melatonin administration in May depressed plasma testosterone levels, testicular reactivation was advanced by 1 month the following year, and the characteristic prehibernal gain in body mass was abolished. Melatonin administration in August had no effect on plasma testosterone concentrations but reduced body mass fluctuations before and during hibernation. Hedgehogs receiving melatonin in September recovered early from hibernal body mass loss and showed a 2 month advance in testicular reactivation the following year. Maintaining hedgehogs at 18L:6D photoperiod, however, elevated plasma melatonin concentrations. Testicular reactivation the following spring was delayed by 1 month, ended 3 months early, and testosterone concentrations were depressed. All treatments depressed plasma thyroxin levels. These results suggest that elevated melatonin levels during winter are important in the regulation of endogenous endocrine cycles in the hedgehog. Hedgehogs do not respond positively to melatonin at the end of the breeding season, but are again responsive to melatonin as early as September.

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“…In non-experimental hedgehogs [Fowler, 1988b], plasma melatonin was elevated between November and February at photoperiods shorter than 10L:14D, which were suggested by Fowler [ 1988131 as important in regulating R e t r a c t e d their endogenous cycles. The characteristic February/March peak in plasma testosterone concentrations occurs while melatonin levels are falling.…”

Section: Discussionmentioning

confidence: 93%

Effect of Melatonin Administration and Long Day‐Length on Endocrine Cycles in the Hedgehog Erinaceus europaeus

Fowler

¹

,

Racey

²

1990

Journal of Pineal Research

View full text Add to dashboard Cite

The effects of exogenous melatonin (subcutaneous implants containing 0.031 +/- 0.006 mg/gm body mass melatonin) or long photoperiod (18L:6D) on wild-caught adult male hedgehogs were studied. Hedgehogs were implanted with melatonin-filled or empty capsules in May, August, or September, or maintained under long photoperiod from August. Blood samples collected at monthly intervals were assayed for testosterone, melatonin, and thyroxin. Melatonin-filled capsules elevated plasma melatonin concentrations for 4-6 months. Although melatonin administration in May depressed plasma testosterone levels, testicular reactivation was advanced by 1 month the following year, and the characteristic prehibernal gain in body mass was abolished. Melatonin administration in August had no effect on plasma testosterone concentrations but reduced body mass fluctuations before and during hibernation. Hedgehogs receiving melatonin in September recovered early from hibernal body mass loss and showed a 2 month advance in testicular reactivation the following year. Maintaining hedgehogs at 18L:6D photoperiod, however, elevated plasma melatonin concentrations. Testicular reactivation the following spring was delayed by 1 month, ended 3 months early, and testosterone concentrations were depressed. All treatments depressed plasma thyroxin levels. These results suggest that elevated melatonin levels during winter are important in the regulation of endogenous endocrine cycles in the hedgehog. Hedgehogs do not respond positively to melatonin at the end of the breeding season, but are again responsive to melatonin as early as September.

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“…Although the effect of CORT on torpor has been previously considered, studies have focused primarily on seasonal patterns of adrenal glucocorticosteroids in hibernating mammals and the relation of those patterns to the coming hibernation season (Saboureau and Boissin, 1983;Shivatcheva et al, 1988;Armitage, 1991;Boswell et al, 1994). With a few exceptions (e.g., Fowler, 1988), the findings of these studies generally demonstrate that plasma corticosteroid concentrations are lowest around the time when animals emerge from their hibernacula in spring, thereafter increasing to their peak values just before the next hibernation season begins. Although daily torpor and seasonal hibernation are considered by many to represent homologous physiological states, there are substantial differences in the energy ecology of animals that must prepare for months of hibernation in comparison with those that can make use of brief periods of torpor during each 24-h cycle.…”

Section: Relation Between Cort and Torpor In Birds And Mammalsmentioning

confidence: 99%

Corticosterone and Nocturnal Torpor in the Rufous Hummingbird (Selasphorus rufus)

Hiebert¹,

Salvante²,

Ramenofsky³

et al. 2000

General and Comparative Endocrinology

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Seasonal endocrine cycles in the European hedgehog, Erinaceus europaeus

Abstract: Summary. Adult

Cited by 29 publications

References 37 publications

Retracted: Effect of Melatonin Administration and Long Day‐Length on Endocrine Cycles in the Hedgehog Erinaceus europaeus

Retracted: Effect of Melatonin Administration and Long Day‐Length on Endocrine Cycles in the Hedgehog Erinaceus europaeus

Effect of Melatonin Administration and Long Day‐Length on Endocrine Cycles in the Hedgehog Erinaceus europaeus

Corticosterone and Nocturnal Torpor in the Rufous Hummingbird (Selasphorus rufus)

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