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A novel avian hypothalamic peptide inhibiting gonadotropin release.
It is shown, in a bird, that the hypothalamus also contains a novel peptide which inhibits gonadotropin release, the first hypothalamic peptide inhibiting gonadotropic hormone reported in a vertebrate.
Thyrotrophin in the pars tuberalis triggers photoperiodic response
Two waves of gene expression are identified in the quail MBH associated with the initiation of photoinduced secretion of luteinizing hormone and increased TSH in the pars tuberalis seems to trigger long-day photoinduced seasonal breeding.
Hormone levels predict individual differences in reproductive success in a passerine bird
Hormones concentrations both before and during breeding, as well as their seasonal dynamics, predict reproductive success, suggesting that individual variation in absolute concentrations and in plasticity is functionally significant, and, if heritable, may be a target of selection.
Orchestration of avian reproductive effort: an integration of the ultimate and proximate bases for flexibility in clutch size, incubation behaviour, and yolk androgen deposition
Evidence in birds of altricial species is reviewed for the presence of at least two behavioural mechanisms to buffer challenges and take advantage of opportunities and evidence for and against the seasonal coordination of these mechanisms through seasonal changes in plasma concentrations of the pituitary hormone prolactin.
Physiological roles of chicken LHRH-I and -II in the control of gonadotrophin release in the domestic chicken.
Observations suggest that gonadotrophin secretion in the hen is more likely to be directly regulated by cLHRH-I than by cCL HRH-II, which is most abundant in the diencephalon.
Control of luteinizing hormone and prolactin secretion in birds.
In birds exposed to seasonal changes in daylength, the seasonally maximal concentrations of plasma Prolactin associated with the development of photorefractoriness can be explained, in part, by the saturation daylength for photoinduced prolactin release being reached in late spring/mid summer.
Photoperiodic Regulation of Seasonal Breeding in Birds
  • P. Sharp
  • Biology, Medicine
    Annals of the New York Academy of Sciences
  • 1 April 2005
Analysis of the sites of expression of clock genes suggests that the biological clock for reproductive photoperiodic time measurement is in the medial basal hypothalamus, and photoinduced increase in T3 may stimulate the release of gonadotrophin‐releasing hormone through thyroid hormone receptors in the median eminence.
Sex differences in the LH responses to chicken LHRH-I and -II in the domestic fowl.
The interaction between LHRH-I and -II and the gonadotrophs is sexually differentiated in the domestic fowl and a new homologous radioimmunoassay was established for cLH.
Increasing Temperature, Not Mean Temperature, Is a Cue for Avian Timing of Reproduction
It is shown that females fine-tune their laying in response to a seasonal increase in temperature, whereas mean temperature and daily temperature variation alone do not affect laying dates, and similarities between sisters in their laying dates indicate genetic variation in cue sensitivity.
Photoperiodic requirements for LH release in juvenile broiler and egg-laying strains of domestic chickens fed ad libitum or restricted diets.
  • I. Dunn, P. Sharp
  • Biology, Medicine
    Journal of reproduction and fertility
  • 1 September 1990
There was no significant interaction between dietary treatment and photoinduced LH release in birds of either strain and a significant effect of dietary treatment was observed on the changes in concentration of plasma LH in the nonphotostimulated dwarf broiler, but not in the egg-laying bird.