Author/Authors :
Noroozi، Atefeh نويسنده Department of Animal Sciences, College of Agriculture, Shiraz University, Shiraz, Iran , , Jafarzadeh Shirazi، Mohammad Reza نويسنده Department of Animal Science, College of Agriculture, Shiraz University, Shiraz, Iran , , Tamadon، Amin نويسنده Department of Clinical Sciences, School of Veterinary Medicine, Shiraz University & Stem Cell and Transgenic Technology Research Center, Shiraz Uni Tamadon, Amin , Moghadam، Ali نويسنده Biotechnology Institute, College of Agriculture, Shiraz University, Shiraz, Iran , , Niazi، Ali نويسنده Biotechnology Institute, College of Agriculture, Shiraz University, Shiraz, Iran ,
Abstract :
Background: RFamide-related peptide-3 (RFRP-3) inhibits gonadotropin releasing hormone
(GnRH) and luteinizing hormone (LH) secretion in rats. This study evaluates the
effects of litter size and suckling intensity on RFRP mRNA expression in the dorsomedial
hypothalamic nucleus (DMH) of rats.
Materials and Methods: A total of 32 pregnant and 4 non-lactating ovariectomized
(control group) Sprague-Dawley rats were used in this experimental study. Lactating rats
were allotted to 8 equal groups. In 3 groups, the litter size was adjusted to 5, 10, or 15
pups upon parturition. Dams were allowed to suckle their pups continuously until 8 days
postpartum. In the other 3 groups, the litter size was adjusted to 5 pups following birth.
These pups were separated from the dams for 6 hours on day 8 postpartum, after which
the pups were allowed to suckle for 2.5, 5, or 7.5 minutes prior to killing the dams. In
2 groups, lactating rats with 10 and 15 pups were separated from their pups for 6 hours
on day 8 postpartum. In these groups, the pups were allowed to suckle their dams for 5
minutes before the dams were killed. All rats were killed on day 8 postpartum and the
DMH was removed from each rat. We evaluated RFRP mRNA expression using realtime
polymerase chain reaction (PCR).
Results: The expression of RFRP mRNA in the DMH increased with increased litter size
and suckling intensity compared to the controls. The effect of suckling intensity on the
expression of RFRP mRNA was more pronounced compared to the litter size.
Conclusion: Increased litter size and suckling intensity stimulated RFRP mRNA expression
in the DMH which might contribute to lactation anestrus in rats.
