title: Increased Litter Size and Suckling Intensity Stimulate mRNA of RFamide-related Peptide in Rats.
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.
  
  
  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.
  
  
  CONCLUSIONS
  Increased litter size and suckling intensity stimulated RFRP mRNA expression in the DMH which might contribute to lactation anestrus in rats.
authors.affiliation: Department of Animal Sciences, College of Agriculture, Shiraz University, Shiraz, Iran.
authors.forename: Atefeh
authors.initials: A
authors.lastname: Noroozi
authors.affiliation: Department of Animal Sciences, College of Agriculture, Shiraz University, Shiraz, Iran.
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Jafarzadeh Shirazi
authors.affiliation: Transgenic Technology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: Amin
authors.initials: A
authors.lastname: Tamadon
authors.affiliation: Biotechnology Institute, College of Agriculture, Shiraz University, Shiraz, Iran.
authors.forename: Ali
authors.initials: A
authors.lastname: Moghadam
authors.affiliation: Biotechnology Institute, College of Agriculture, Shiraz University, Shiraz, Iran.
authors.forename: Ali
authors.initials: A
authors.lastname: Niazi
keywords: Dorsomedial Hypothalamic Nucleus; Lac- tation; RFRP mRNA; Rat; Suckling Intensity