02514naa a2200277 a 450000100080000000500110000800800410001902400520006010000180011224501500013026000090028052017030028965000180199265000130201065000150202365000140203865000170205265000100206965000170207965000190209665000150211565000100213065000170214070000190215777300600217615236762023-06-28       1979    bl uuuu     u00u1 u    #d7 ahttps://doi.org/10.1095/biolreprod20.4.9652DOI1 aWILSON, P. R.  aStudies of reproductive development in Romney ramsbI. Basal levels and plasma profiles of LH, testosterone and prolactin.h[electronic resource]  c1979  aAbstract: In a study of endocrine changes during reproductive development in rams, single plasma samples were collected at birth; then 4 samples, 30 min apart, were collected each 2 weeks from 2?32 weeks of age. Eight Romney rams from a group of 32 were selected at random for each bleeding and plasma LH, testosterone and prolactin levels were estimated by specific radioimmunoassays. Plasma LH levels rose to a peak at 6 weeks, decreased until 16 weeks and then remained relatively constant, while testosterone levels increased steadily from low levels at birth to highest levels at 28?32 weeks of age. Prolactin levels rose to a plateau by 6 weeks, remained high until 18 weeks and decreased gradually until 32 weeks. In a second experiment, 8 rams were sampled each 20 min for 8 h on the 6th, 14th and 22nd weeks of life and plasma LH, testosterone and prolactin concentrations measured. LH was secreted in a pulsatile manner and secretion rates were highest at 14 weeks of age. Testosterone peaks were observed following each LH peak at 14 and 22 weeks, but followed only 6 of 11 LH peaks at 6 weeks of age. Testosterone peak levels were highest at 22 weeks of age. A quantitative relationship was observed between testosterone peaks and preceding LH peaks at 14 and 22 weeks of age, but not at 6 weeks. Prolactin secretion profiles of prepubertal (6 weeks) and sexually maturing (14 and 22 weeks) rams were similar and levels fluctuated markedly at each age. A stress-induced elevation of plasma LH levels was observed in approximately 70% of animals sampled in both experiments, while the occurrence of similar elevations of plasma prolactin levels due to stressful procedures was confirmed.  aEndocrinology  aHormones  aPhysiology  aProlactin  aReproduction  aSheep  aTestosterone  aEndocrinologia  aFisiologia  aOvino  aReprodução1 aLAPWOOD, K. R.  tBiology of Reproductiongv. 20, n. 4, p. 965-970, 1979.