Leptin regulation of pubertal maturation in intact and pinealectomized female rats

Abstract

Histological changes in bone structure were induced at 12 weeks by experimental administration of bisphosphonates, which have been associated with osteonecrosis of the jaws. The purpose of this study was to determine the effect of local administration of bisphosphonate on bone formation in rats. Surgically created bone defects were evaluated at 12 weeks by histological examination after bisphosphonate administration. Fifteen Wistar rats that underwent surgery to create a bone defect at the right femur were divided in 3 groups: 2 experimental groups and a control group. The 1st experimental group received bisphosphonate as a single 1-mL dose into the bone defect, the 2nd experimental group received 1 mL of bisphosphonate as a 10-day fractionated dose, and the control group comprised rats who did not receive any bisphosphonate. At 12 weeks after the injection, new bone tissue was collected and a histological examination was performed. At 12 weeks after the bisphosphonate administration, bone repair processes were found in both the experimental and control groups. The bone continuity in the intervention area was ensured by a continuous layer of bone tissue. Compared with the control, the repair processes were significantly more advanced in the experimental groups, the layer of bone tissue covering the bone defect being thicker and more consolidated and the trabeculae from the Haversian canal being thicker and denser. External and internal consolidation structures were present in animals from all of the groups. Bisphosphonate had a positive influence on bone formation. The stimulatory effect of the bisphosphonate increased with the number of administered doses.

Endogeneous Signals and Mammalian Puberty Onset: A Review

“…All these findings suggest that leptin directly triggers pubertal onset as well as acting as a permissive metabolic signal in this process. In one of the study (Emine et al, 2013) leptin administration was started before weaning and animals were continuously given leptin for 28 days. In order to examine melatonin modulation of leptin's effects on pubertal maturation, pinealectomies (PNX) were performed on a group of rats to minimize melatonin secretion in the present study.…”