Enhancement of the luteinising hormone surge by male olfactory signals is associated with anteroventral periventricular Kiss1 cell activation in female rats.

Olfactory stimuli play an important role in regulating reproductive functions in mammals. The present study investigated the effect of olfactory signals derived from male rats on kisspeptin neuronal activity and luteinising hormone (LH) secretion in female rats. Wistar-Imamichi strain female rats were ovariectomised (OVX) and implanted with preovulatory levels of 17ß-oestradiol (E2 ). OVX+E2 rats were killed 1 hour after exposure to either: clean bedding, female-soiled bedding or male-soiled bedding. Dual staining for Kiss1 mRNA in situ hybridisation and c-Fos immunohistochemistry revealed that the numbers of Kiss1-expressing cells and c-Fos-immunopositive Kiss1-expressing cells in the anteroventral periventricular nucleus (AVPV) were significantly higher in OVX+E2 rats exposed to male-soiled bedding than those of the other groups. No significant difference was found with respect to the number of c-Fos-immunopositive Kiss1-expressing cells in the arcuate nucleus and c-Fos-immunopositive Gnrh1-expressing cells between the groups. The number of c-Fos-immunopositive cells was also significantly higher in the limbic system consisting of several nuclei, such as the bed nucleus of the stria terminalis, the cortical amygdala and the medial amygdala, in OVX+E2 rats exposed to male-soiled bedding than the other groups. OVX+E2 rats exposed to male-soiled bedding showed apparent LH surges, and the peak of the LH surge and area under the curve of LH concentrations in the OVX+E2 group were significantly higher than those of the other two groups. These results suggest that olfactory signals derived from male rats activate AVPV kisspeptin neurones, likely via the limbic system, resulting in enhancement of the peak of the LH surge in female rats. Taken together, the results of the present study suggests that AVPV kisspeptin neurones are a target of olfactory signals to modulate LH release in female rats.

Effects of guided bone regeneration with non-resorbable and bioabsorbable barrier membranes on osseointegration around hydroxyapatite-coated and uncoated threaded titanium dental implants placed into a surgically-created dehiscence type defect in rabbit tibia: a pilot study.

The purpose of this study was to evaluate the effects of guided bone regeneration (GBR) with either a non-resorbable (ePTFE) or bioabsorbable barrier membrane (RSLT) on osseointegration and extent of bone formation around hydroxyapatite-coated (HA) and uncoated threaded titanium (Ti) dental implants placed into surgically-created dehiscence type defects in rabbit tibia. A dehiscence type bone defect, approximately 3 mm in width and height was surgically created on the outer surface of the bone in each tibia of 9 rabbits. For the conventional group, either a HA or a Ti implant was then placed at this site. After the same procedure was performed as in the conventional group, the implant site of the GBR group was covered with either an ePTFE or a RSLT. After 4 months, the rabbits were sacrificed. Specimens were prepared and examined histometrically. It was found that the mean percentage of osseointegration tended to increase in HA compared to Ti implants, both with and without membranes. There was a tendency that the extent of newly regenerated bone was higher in the GBR group than that in the conventional group.