PMID- 11812629
OWN - NLM
STAT- MEDLINE
DCOM- 20020307
LR  - 20191105
IS  - 0378-4320 (Print)
IS  - 0378-4320 (Linking)
VI  - 69
IP  - 3-4
DP  - 2002 Feb 15
TI  - Effect of melatonin on daily LH secretion in intact and ovariectomized ewes 
      during the breeding season.
PG  - 187-98
AB  - This study was conducted to find out whether daily LH secretion in ewes may be 
      modulated by melatonin during the breeding season, when the secretion of both 
      hormones is raised. Patterns of plasma LH were determined in luteal-phase ewes 
      infused intracerebroventricularly (icv.) with Ringer-Locke solution (control) and 
      with melatonin (100 microg/100 microl/h). Response in LH secretion to melatonin 
      was also defined in ovariectomized (OVX) ewes without and after estradiol 
      treatment (OVX+E2). Basal LH concentrations by themselves did not differ 
      significantly before, during and after both control and melatonin infusions in 
      intact, luteal-phase ewes. However, single significant (P<0.05) increases in LH 
      concentration were noted during the early dark phase in the control and 1h after 
      start of infusion in melatonin treated ewes. In both OVX and OVX+E2 ewes, 
      melatonin decreased significantly (P<0.01, P<0.05, respectively) mean plasma LH 
      concentrations as compared to the levels noted before the infusions. In OVX+E2 
      ewes, a single significant (P<0.05) increase in LH occurred 1h after start of 
      melatonin treatment, similarly as in luteal-phase ewes. No significant 
      differences in the frequencies of LH pulses before, during and after melatonin 
      infusion were found in all treatments groups. In conclusion, melatonin may exert 
      a modulatory effect on daily LH secretion in ewes during the breeding season, 
      stimulating the release of this gonadotropin in the presence of estradiol 
      feedback and inhibiting it during steroid deprivation. Thus, estradiol seems to 
      be positively linked with the action of melatonin on reproductive activity in 
      ewes.
FAU - Misztal, Tomasz
AU  - Misztal T
AD  - Department of Endocrinology, The Kielanowski Institute of Animal Physiology and 
      Nutrition, Polish Academy of Sciences, 05-110 Jablonna n., Warsaw, Poland. 
      t.misztal@ifzz.pan.pl
FAU - Romanowicz, Katarzyna
AU  - Romanowicz K
FAU - Barcikowski, Bernard
AU  - Barcikowski B
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - Netherlands
TA  - Anim Reprod Sci
JT  - Animal reproduction science
JID - 7807205
RN  - 4TI98Z838E (Estradiol)
RN  - 9002-67-9 (Luteinizing Hormone)
RN  - JL5DK93RCL (Melatonin)
SB  - IM
MH  - Animals
MH  - Breeding
MH  - Estradiol/administration & dosage/pharmacology
MH  - Female
MH  - Injections, Intraventricular/veterinary
MH  - Luteal Phase
MH  - Luteinizing Hormone/*drug effects/*metabolism
MH  - Melatonin/metabolism/*pharmacology
MH  - Ovariectomy/veterinary
MH  - Sheep/*physiology
EDAT- 2002/01/29 10:00
MHDA- 2002/03/08 10:01
CRDT- 2002/01/29 10:00
PHST- 2002/01/29 10:00 [pubmed]
PHST- 2002/03/08 10:01 [medline]
PHST- 2002/01/29 10:00 [entrez]
AID - S0378432001001944 [pii]
AID - 10.1016/s0378-4320(01)00194-4 [doi]
PST - ppublish
SO  - Anim Reprod Sci. 2002 Feb 15;69(3-4):187-98. doi: 10.1016/s0378-4320(01)00194-4.