ESPE Abstracts

Background: Spexin (SPX)and kisspeptin (KISS) are peptides involved in the regulation of body weight, metabolism and reproduction.

Aim: To assess expression levels ofSPX andKISS in serum, ovarian tissue and white adipose tissue (WAT) of female albino Wistar rats as related to pubertal status and metabolic surrogates of puberty.

Materials and Methods: Twenty-six female albino Wistar rats were divided into three groups as prepubertal (n = 6)(postnatal day[PND]28), pubertal(n = 10)(PND 42) and postpubertal (n = 10)(PND 70). For determination of puberty, vaginal opening and first estrus were observed and corpus luteum in the ovary was histomorphologically demostrated. The rats were sacrificed after intracardiac blood samples were drawn. All the rats were fed with breast milk untilPND21and received normal diet afterwards. Serum LH, estradiol (E2), total Ieptin (Iep), soluble lep receptor (s-IepR), SPX, KISS, IGF1, fasting glucose and insulin levels (HOMA-Insulin resistance(IR)= glucose(mmol/l)x insulin/22.5) were measured. Total RNA was isolated from ovarian tissue and WAT samples and expressions of SPX and KISS were examined by immunohistochemistry and real time quantitative PCR (qRT-PCR). Statistical significance was granted for p less than 0.05.

Results: The ratios of change in weight to birth weight were significantly higher in pubertal and postpubertal groups than in the prepubertal group; as expected (P < 0.001). Serum LH levels were lower in postpubertal rats than in pubertal and prepubertal groups(P = 0.015) and E2 and IGF1 levels were comparable(P >0.05). Serum KISS and SPX levels were significantly lower in pubertal group than in prepubertal and postpubertal groups (P = 0.012and P = 0.005; respectively). Serum SPX levels were similar between prepubertal and postpubertal groups(P = 0.428). HOMA-IR was significantly higher in pubertal and postpubertal rats than in prepubertal rats (P = 0.018and 0.015;respectively). SerumIGF1and total lep/s-lepR ratios were similar between the groups(P >0.05for all). Serum SPX levels correlated significantly with serum KISS (r =0.504, P = 0.009). In the ovarian tissue, expression levels of KISS and SPX were comparable between the groups (P = 0.141and P = 0.175;respectively). In WAT, expression levels ofSPXwere lower in pubertal rats than in prepubertal and pubertal counterparts (P = 0.047and P = 0.050). Likewise, expression levels of KISS were also lower in pubertal rats, but not significantly(P = 0.06).

Conclusion: s: To our knowledge, this is the first study to demonstrate reduced expression levels of SPX in WAT in female pubertal rats in parallel with the decreased serum SPX levels. The increased levels of KISS in prepubertal female rats confirms the difference in relation to the dynamics of KISS levels in female rats during puberty when compared to humans. Our findings may serve to emphasize the need to assess the regulatory role of SPX in humans.