Nesfatin-1 expression and blood plasma concentration in female dogs suffering from cystic endometrial hyperplasia and pyometra and its possible interaction with phoenixin-14.

Background: Nesfatin-1 is a neuropeptide that regulates the hypothalamic-pituitary-gonadal axis and may play a role in uterus function. It is co-expressed with other peptides, such as phoenixin, which can influence sex hormone secretion. Our previous research has confirmed that phoenixin-14 is involved in the development of cystic endometrial hyperplasia (CEH) and pyometra in dogs. Therefore, based on the similarities and interactions between these neuropeptides, we hypothesized that nesfatin-1 might also regulate the reproductive system in dogs. This study aimed to determine the expression of nesfatin-1 and its interaction with phoenixin-14 in dogs with CEH or pyometra compared to healthy females, and concerning animals' body condition score (BCS 4-5/9 vs. BCS > 5/9).

Results: The analysis of nesfatin-1 in the uterus of bitches consisted of qPCR, western blot and immunofluorescence assays, and ELISAs. The results showed significantly higher nesfatin-1 encoding gene, nucleobindin-2 mRNA (Nucb2) and nesfatin-1 protein expression in overweight females and those suffering from CEH or pyometra compared to healthy animals. The immunoreactivity of nesfatin-1 was elevated in the uteri of bitches with higher BCS > 5/9. Moreover, nesfatin-1 blood concentrations increased in all examined overweight bitches. In the case of phoenixin signals, we found opposite results, regardless of the female body condition score.

Conclusion: The etiology of CEH and pyometra are not fully known, although we have expanded the level of knowledge with respect to the possible interaction of nesfatin-1 and phoenixin in female dogs' uteri. They interact oppositely. With increasing female body weight, the expression of nesfatin-1 in the uterus and its peripheral blood concentration increased. However, for female dogs affected by CEH and pyometra, a decreased level of phoenixin-14, irrespective of their body condition score is characteristic. This knowledge could be crucial in the development of biomarkers for these conditions, which may lead to earlier recognition.