Serum Androgen and Gonadotropin Profiles Over the First Year of Life in Ram Lambs and the Effect of Season of Birth

Cook, Susan; Rawlings, N. C.

doi:10.4141/cjas86-008

Cited by 4 publications

(3 citation statements)

References 23 publications

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“…In the present study, the age trends for LH pulse frequency and amplitude reflected those reported by Olster & Foster (1986 Cook & Rawlings (1986 Differences between treatment groups are significant: *P < 005 or **P < 001. Columns, within each treatment group, with different subscripts are significantly different (P < 005).…”

Section: Discussionsupporting

confidence: 59%

“…Serum testosterone concentrations were estimated for each lamb, at each treatment, on a serum pool of samples taken once an hour over the sampling periods. Serum concentrations of testosterone were determined in a previously validated radioimmunoassay (Cook & Rawlings, 1986), with samples batched for analysis as described for LH and FSH. Sensitivity was 003 ng/ml.…”

Section: Introductionmentioning

confidence: 99%

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Maturational changes in opioidergic control of luteinizing hormone and follicle-stimulating hormone in ram lambs

Rawlings¹,

Churchill²,

Currie³

et al. 1991

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20, 25, 30 and 35 weeks of age. Naloxone had no effect on age at sexual maturity (controls 239 \ m=+-\ 23 days; naloxone 232 \ m=+-\33 days). The only significant (P < 0\m=.\05) effect of naloxone on FSH was a greater pulse amplitude in 10-week-old treated lambs than in control lambs. Naloxone treatment resulted in greater LH pulse amplitude at 5 and 10 weeks of age (P < 0\m=.\05), lower basal serum concentration of LH at 10 weeks of age (P < 0\m=.\05),greater LH pulse frequency at 25 weeks of age (P < 0\m=.\05), and greater mean serum concentrations of LH, basal LH and LH pulse amplitude at 35 weeks of age (P < 0\m=.\01) than in the controls.In both groups of lambs, mean and basal FSH, and LH and FSH pulse amplitude were highest at 5 weeks of age and fell with age. LH pulse amplitude was lowest at 35 weeks of age (P < 0\m=.\05). Mean and basal LH were higher at 10 weeks of age than at all other times in the control lambs only. In control and treated lambs, FSH pulse frequency did not change with age, but LH pulse frequency was high at 35 weeks of age (P < 0\m=.\05) and mean serum concentrations of testosterone rose with age (P < 0\m=.\05).We conclude that (i)

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Section: Discussionsupporting

confidence: 59%

Section: Introductionmentioning

confidence: 99%

Maturational changes in opioidergic control of luteinizing hormone and follicle-stimulating hormone in ram lambs

Rawlings¹,

Churchill²,

Currie³

et al. 1991

Reproduction

Self Cite

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“…Previous reports on changes in circulating FSH in developing rams have generally depicted progres¬ sive elevations from birth to a maximum at about 5 to 9 weeks of age, followed by either a sharp or a gradual decline (Cook & Rawlings 1986, Yarney & Sanford 1989, Hochereau-de Reviers 1991.…”

Section: Discussionmentioning

confidence: 98%

Ontogeny of FSH receptor messenger ribonucleic acid transcripts in relation to FSH secretion and testicular function in sheep

Yarney

Fahmy²,

Sairam³

et al. 1997

Journal of Molecular Endocrinology

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The role of alternative splicing of the FSH receptor gene in the generation of FSH receptor proteins and testicular function remains an enigma. To address this issue, this investigation was conducted to determine variations in the expression of alternate FSH receptor mRNA transcripts in relation to changes in FSH release, hormone binding activity and testicular function during pubertal development of ram lambs from two genotypes of sheep (Romanov and a cross between Booroola x DLS) with different sexual precocity. Serum 17 beta-estradiol and testosterone concentrations were used as indices of Sertoli cell and testicular function. The results indicated that increases in Sertoli cell and testicular function normally seen during pubertal development are accompanied by age-dependent reductions in concentration of functional FSH receptors, as determined by binding of iodinated FSH to testicular membrane preparations. During the course of these changes, FSH release was either maintained at a steady level in Romanov lambs or it was gradually reduced in the Booroola x DLS cross, thus indicating that the testis had become more responsive to hormonal signal. This acquisition of heightened sensitivity was also associated with contrasting changes in the level of expression of FSH receptor mRNA transcripts. For both geno-types of sheep, 5 distinct species of mRNA transcripts of approximately 1.1, 1.5, 2.0, 2.5 and 6.5 kb were highly expressed from 11 to 22 weeks of age. Amongst these transcripts, the 1.1 kb molecular species was the most abundant. Specific probing for a previously cloned transcript called 151A1 representing the first 4 exons of the FSH receptor gene revealed a paradoxical increase in the level of expression from 11 weeks up to a maximum at 18-22 weeks of age for both genotypes. Collectively, the results indicated that contrasting changes in the production of specific alternatively spliced mRNA transcripts may mediate changes in FSH receptor expression which apparently accounts for the augmentation in sensitivity and function of the testis during pubertal development. Furthermore, the data provide the first important indication that the novel truncated transcript (151A1), which predictably encodes a soluble protein of either intra- or extracellular fate, could be physiologically relevant.

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The relationship between scrotal circumference and quantitative testicular traits in yearling beef bulls

et al. 1994

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Serum Androgen and Gonadotropin Profiles Over the First Year of Life in Ram Lambs and the Effect of Season of Birth

Cited by 4 publications

References 23 publications

Maturational changes in opioidergic control of luteinizing hormone and follicle-stimulating hormone in ram lambs

Maturational changes in opioidergic control of luteinizing hormone and follicle-stimulating hormone in ram lambs

Ontogeny of FSH receptor messenger ribonucleic acid transcripts in relation to FSH secretion and testicular function in sheep

The relationship between scrotal circumference and quantitative testicular traits in yearling beef bulls

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