AJP - Regulatory, Integrative and Comparative Physiology, Vol 265, Issue 1 240-R245, Copyright © 1993 by American Physiological Society
Reanalysis of the rat proestrous LH surge by deconvolution analysis
J. D. Veldhuis, M. L. Johnson and R. V. Gallo
Department of Internal Medicine and Pharmacology, University of Virginia Health Sciences Center, Charlottesville 22908.
To evaluate the temporal mechanisms that give rise to the spontaneous
proestrous surge of luteinizing hormone (LH) in the rat, we have applied
deconvolution analysis to earlier immunoreactive LH concentration vs. time
profiles obtained by sampling blood in proestrus at 2- to 3-min intervals
in 10 animals over a span of 160-300 min. Six other animals were bled in
6-min intervals on day 1 of diestrus. Deconvolution analysis permitted us
to calculate the number, duration, amplitude (maximal release rates), and
mass of underlying LH secretory bursts and to simultaneously estimate basal
secretion and the half-life of endogenous LH in each animal. Proestrus rats
exhibited a significant increase in the number of computer-identified LH
secretory bursts per hour (1.8 +/- 0.2 vs. 1.1 +/- 0.01 on diestrus, P <
0.01), with a corresponding reduction in the LH intersecretory burst
interval from 61 +/- 6.4 min (diestrus) to 25 +/- 2.7 min (proestrus, P
< 0.01). There was a remarkable 16-fold increase in the mass of LH
secreted per burst, which rose from 72 +/- 5.2 to 1,230 +/- 200 ng/ml (P
< 0.01). This resulted from a sixfold increase in LH secretory burst
amplitude and a doubling of burst duration. The total amount of LH released
in a burstlike fashion during the proestrous LH surge rose 20-fold, and
calculated basal LH secretion increased to approximately 25% of this value.
Of interest, the computed half-life of endogenous LH also increased from 10
+/- 1.1 to 19 +/- 3.7 min (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
