PMID- 9725714
OWN - NLM
STAT- MEDLINE
DCOM- 19981110
LR  - 20190921
IS  - 0953-8194 (Print)
IS  - 0953-8194 (Linking)
VI  - 10
IP  - 8
DP  - 1998 Aug
TI  - Ovarian steroid-independent diurnal rhythm in cyclic GMP/nitric oxide efflux in 
      the medial preoptic area: possible role in preovulatory and ovarian 
      steroid-induced LH surge.
PG  - 617-25
AB  - The aim of this study was to evaluate the relationship between cyclic LH 
      hypersecretion and nitric oxide (NO) release in the medial preoptic area (MPOA), 
      the hypothalamic site implicated in induction of LH hypersecretion. The MPOA 
      extracellular cyclic GMP (cGMP) efflux (an index of NO release), was monitored by 
      microdialysis. Quite unexpectedly, we observed a daily afternoon rise in the MPOA 
      cGMP efflux in cycling female rats on proestrus and diestrus II, in 
      ovariectomized (ovx) rats and in ovx rats treated with ovarian steroids to induce 
      the LH surge. The daily rise in cGMP efflux occurred earlier in diestrous and in 
      estradiol benzoate (EB)-treated ovx rats than in ovx rats. Progesterone (P) 
      injection to estrogen-primed ovx rats further advanced the onset of the rise 
      close to the earliest time of rise as seen on proestrus. The afternoon increase 
      in the cGMP efflux in proestrous rats was abolished by pentobarbital treatment 
      that blocked the LH surge. Intracerebroventricular (i.c.v.) injection of 1 
      H-[1,2,4]oxadiazo[4,3-a]quinoxalin-one (ODQ), a selective inhibitor of soluble 
      guanylyl cyclase, suppressed the P-induced LH surge in EB-primed ovx rats, but 
      not basal LH secretion in unprimed ovx rats. Analysis of brain NOS (bNOS) levels 
      in the POA by Western blotting showed that the morning bNOS levels were higher in 
      the POA of EB-treated rats than in unprimed ovx rats. Further, with the exception 
      of ovx rats treated with sequential EB and P treatment, the POA bNOS levels rose 
      significantly in the afternoon in unprimed ovx and EB-treated ovx rats. 
      Collectively, these findings reveal a diurnal rhythm in the MPOA cGMP/NO efflux 
      that is ovarian steroid-independent. Ovarian steroids apparently shift the timing 
      of the afternoon rise in cGMP/NO efflux to synchronize with the activation of 
      steroid-dependent neuronal systems responsible for the LH surge.
FAU - Pu, S
AU  - Pu S
AD  - Department of Neuroscience, University of Florida College of Medicine, 
      Gainesville 32610, USA.
FAU - Kalra, P S
AU  - Kalra PS
FAU - Kalra, S P
AU  - Kalra SP
LA  - eng
GR  - HD 08634/HD/NICHD NIH HHS/United States
PT  - Journal Article
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - J Neuroendocrinol
JT  - Journal of neuroendocrinology
JID - 8913461
RN  - 0 (Enzyme Inhibitors)
RN  - 1S4CJB5ZGN (estradiol 3-benzoate)
RN  - 31C4KY9ESH (Nitric Oxide)
RN  - 4TI98Z838E (Estradiol)
RN  - 9002-67-9 (Luteinizing Hormone)
RN  - EC 1.14.13.39 (Nitric Oxide Synthase)
RN  - EC 4.6.1.2 (Guanylate Cyclase)
RN  - H2D2X058MU (Cyclic GMP)
SB  - IM
MH  - Animals
MH  - Blotting, Western
MH  - *Circadian Rhythm
MH  - Cyclic GMP/*metabolism
MH  - Diestrus/metabolism
MH  - Enzyme Inhibitors/pharmacology
MH  - Estradiol/*analogs & derivatives/pharmacology
MH  - Female
MH  - Guanylate Cyclase/antagonists & inhibitors
MH  - Luteinizing Hormone/blood/*metabolism
MH  - Nitric Oxide/*metabolism
MH  - Nitric Oxide Synthase/metabolism
MH  - Ovariectomy
MH  - Preoptic Area/*metabolism
MH  - Proestrus/metabolism
MH  - Rats
MH  - Rats, Sprague-Dawley
EDAT- 1998/09/02 00:00
MHDA- 1998/09/02 00:01
CRDT- 1998/09/02 00:00
PHST- 1998/09/02 00:00 [pubmed]
PHST- 1998/09/02 00:01 [medline]
PHST- 1998/09/02 00:00 [entrez]
AID - 10.1046/j.1365-2826.1998.00245.x [doi]
PST - ppublish
SO  - J Neuroendocrinol. 1998 Aug;10(8):617-25. doi: 10.1046/j.1365-2826.1998.00245.x.