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Jikken Dobutsu

Title:		"Fluctuations in peripheral serum testosterone levels within a day, with age and by sexual stimulation in male beagle dogs bred indoors"
Author(s):		Fukuda S; Nagashima H; Morioka K; Aoki J;
Address:		"Division of Comparative Radiotoxicology, National Institute of Radiological Sciences, Chiba, Japan"
Journal Title:		Jikken Dobutsu
Year:		1988
Volume:		37
Issue:		4
Page Number:		381 - 386
DOI:		10.1538/expanim1978.37.4_381
ISSN/ISBN:		0007-5124 (Print) 0007-5124 (Linking)
Abstract:		"Fluctuations in serum levels of testosterone (T) within a day, both with age and as a result of sexual stimulation, were examined in male beagle dogs. Eighty male dogs aged between 3 months and 16 years and bred in our laboratory were used under strictly controlled breeding conditions (temperature: 22 +/- 1 degree C, relative humidity: 55 +/- 5%, lighting time: 8:00 a.m.-8:00 p.m.). The level of T was measured by an RIA method. In order to examine the fluctuation in T level within a day, blood samples were obtained at 0:00, 6:00, 12:00 and 18:00 in each of five dogs aged 1.7 and 2.1 years. T levels fluctuated with a regular pattern that was lowest at 12:00, and increased to a peak at 18:00-6:00, thereafter decreasing until 12:00. In order to examine the change in T level with age, blood samples were obtained at 9:00, 12:00 and 16:00 from 70 dogs aged between 3 months and 16 years. The regular diurnal pattern of T level was usually seen, and the levels at 12:00 were always low and did not fluctuate at any age except for 6 months, and 13, 14 and 16 years. The T level at 9:00 increased to reach a peak at 4 years, whereas that at 16:00 did so at 2 years. T levels at 9:00 were significantly higher at 4-12 and 14 years than at 3 months, and were higher at 4 years than at 9 months.(ABSTRACT TRUNCATED AT 250 WORDS)"
Keywords:		"Age Factors Animals Animals, Laboratory/*physiology Circadian Rhythm Dogs/*physiology Male Sex Attractants Sexual Behavior, Animal/*physiology Testosterone/*blood;"
Notes:		"MedlineFukuda, S Nagashima, H Morioka, K Aoki, J eng Japan 1988/10/01 Jikken Dobutsu. 1988 Oct; 37(4):381-6. doi: 10.1538/expanim1978.37.4_381"