Blood samples were taken every 15 min (for 4.75 h) from six castrated quail on three separate occasions. The birds were first bled while under short days (comprising 8 h light : 16 h darkness per 24 h; 8L : 16D) and, subsequently, after 1 and 20 days under long days of 16L : 8D. The photoperiodic alteration produced a marked increase in the mean plasma LH concentration of each bird and in four instances the rise was evident after only 1 long day. Pulsatile release patterns were not detected in the plasma LH profiles obtained during exposure to short days or after 1 long day but were pronounced in all of the birds after 20 long days. The peaks (n = 19) occurred on average every 83 ± 14 (S.E.M.) min and had an amplitude of 12.3 ± 1.2 μg/l. After 35 days under 16L : 8D three of the quail were bled more frequently (every 8 min for 2.5 h), allowing the LH pulses to be measured more precisely. Each pulse was composed of a sudden increase in secretion followed by a slower decrease which lasted for approximately 30 min. The development and functional significance of episodic LH release in the quail is discussed.
ASJC Scopus subject areas
- Endocrinology, Diabetes and Metabolism