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Abstract
The changes in gonadotrophin secretion in childhood and puberty involve changes in the pulsatile pattern as well as mean concentration. We have examined pulsatile secretion using 24-h LH profiles in 78 children aged 4·2–15·6 years and six adult men. The profiles were analysed by a method which gives an estimate of peak and baseline levels and by spectral analysis. Prepubertal children were divided into groups by age and pubertal children by pubertal stage.
Baseline LH levels in children aged 4·2–6·9 years were higher than in those aged 7·1–9·8 years. Pulse frequency in both groups was slow (periodicities 140–200 min). In the oldest prepubertal group there was an increase in peak levels with increased spectral power at periodicities of 100–120 min. Pulse frequency did not change in puberty (periodicity 120–160 min). Girls demonstrated an increase in both peak and baseline LH concentrations in early puberty. Boys had an increase in only peak levels in early puberty; there was no increase in baseline concentrations until a testicular volume of 10 ml was attained.
In conclusion, these data show that LH levels do not reach a nadir until 8 years of age. We have detected a sex difference in the pattern of LH secretion seen in early puberty, and this mirrors clinical findings. The mature pattern attained by the end of puberty in both sexes is probably important for fertility.
Journal of Endocrinology (1994) 141, 169–176
Department of Biological Sciences, Biomedical Research Institute, University of Warwick, Gibbett Hill Road, Coventry CV4 7AL, UK
Warwickshire Nuffield Hospital, Leamington Spa, Warwickshire, CV32 6RW, UK
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Department of Biological Sciences, Biomedical Research Institute, University of Warwick, Gibbett Hill Road, Coventry CV4 7AL, UK
Warwickshire Nuffield Hospital, Leamington Spa, Warwickshire, CV32 6RW, UK
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Department of Biological Sciences, Biomedical Research Institute, University of Warwick, Gibbett Hill Road, Coventry CV4 7AL, UK
Warwickshire Nuffield Hospital, Leamington Spa, Warwickshire, CV32 6RW, UK
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Department of Biological Sciences, Biomedical Research Institute, University of Warwick, Gibbett Hill Road, Coventry CV4 7AL, UK
Warwickshire Nuffield Hospital, Leamington Spa, Warwickshire, CV32 6RW, UK
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Department of Biological Sciences, Biomedical Research Institute, University of Warwick, Gibbett Hill Road, Coventry CV4 7AL, UK
Warwickshire Nuffield Hospital, Leamington Spa, Warwickshire, CV32 6RW, UK
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Department of Biological Sciences, Biomedical Research Institute, University of Warwick, Gibbett Hill Road, Coventry CV4 7AL, UK
Warwickshire Nuffield Hospital, Leamington Spa, Warwickshire, CV32 6RW, UK
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Orexin-A and orexin-B, via their receptors orexin-1 receptor (OX1R) and orexin-2 receptor (OX2R) have been shown to play a role in the regulation of feeding, body weight, and energy expenditure. Adipose tissue also contributes significantly to the maintenance of body weight by interacting with a complex array of bioactive peptides; however, there are no data as yet on the expression of orexin components in adipose tissue. We, therefore, analyzed the expression of OX1R and OX2R in human adipose tissue and determined functional responses to orexin-A and orexin-B. OX1R and OX2R mRNA expression was detected in subcutaneous (s.c.) and omental adipose tissue and in isolated adipocytes. Protein for OX1R and OX2R was also detected in whole adipose tissue sections and lysates. Treatment with orexin-A, and orexin-B (100 nM, 24 h) resulted in a significant increase in peroxisome proliferator-activated receptors γ-2 mRNA expression in s.c. adipose tissue (P < 0.05). Hormone sensitive lipase mRNA was significantly reduced in omental adipose tissue with orexin-A and orexin-B treatment (P < 0.05). Glycerol release from omental adipose tissue was also significantly reduced with orexin-A treatment (P < 0.05).
These findings demonstrate for the first time the presence of functional orexin receptors in human adipose tissue and suggest a role for orexins in adipose tissue metabolism and adipogenesis.
