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| Influence of Artificial Light on the Development of the Reproductive System in Prepubertal Female Rabbits (Oryctolagus cuniculus) |
| SU Hang, REN Xu-Fang, LIANG Xiao-Hu, HU Xin-Yue, LUO Gang, WANG Jun-Qi, LI Yan-Hong, LIU Zhe-Liang, WANG Jie, HU Shen-Qiang*, LAI Song-Jia* |
| Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China |
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Abstract Light is one of the crucial environmental factors affecting the reproductive performance of female rabbits (Oryctolagus cuniculus). This study aimed to reveal the influence of artificial light on the reproductive system development of prepubertal female rabbits as well as the underlying mechanisms. A total of sixty 48-day-old female Tianfu black rabbits were equally divided into the light and control groups. After 10 d of acclimation, the light group was treated with artificial light for consecutive 12 d (16 h per day), while the control group was fed under natural light. After treatment, 6 rabbits randomly selected from each group were slaughtered. Thereafter, the relative weight of reproductive organs was recorded, the concentrations of plasma melatonin (MLT), estradiol (E2), prostaglandin E2 (PGE2), and progesterone (P4) were measured using ELISA, histological changes in the ovary, oviduct, and uterus were observed using hematoxylin & eosin (HE) staining, and qRT-PCR was used to detect the relative expression of the MLT receptor (MTNR1A) gene, the P4 receptor (PR) gene, the E2 receptor (ERA and ERB) genes, and the PGE2 receptor (EP1~4) genes in the reproductive system. The results showed that compared to the control group, artificial light significantly increased the weight of bilateral ovaries, oviducts, and uteruses as well as the relative weight of bilateral oviducts and uteruses (P<0.05). Histological results showed that both tertiary and mature follicles were present in the ovaries treated with artificial light but were absent in the control group. Meantime, artificial light increased the thickness of the endometrium, the muscular layer, and the serosa of either the oviduct or uterus. In addition, compared to the control group, artificial light decreased plasma levels of MLT, increased those of PGE2 and P4, and significantly decreased those of E2 (P<0.05). Finally, the mRNA levels of MTNR1A and ERB in both the ovary and uterine body, PR in all reproductive organs, EP1~3 in the ovary, EP1 and EP3~4 in the uterine horn, and EP2~4 in the oviduct were significantly or extremely significantly induced by artificial light (P<0.05 or P<0.01). These results indicated that artificial light could influence plasma levels of reproduction-related hormones through both its indirect effects on the hypothalamic-pituitary axis and direct actions on the reproductive system, which promoted the development of the ovary, oviduct, and uterus of prepubertal female rabbit by further activating respective signaling transduction pathways. This study provides the theoretical basis and fundamental information for elucidating the mechanisms initiating puberty in female rabbits.
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Received: 12 June 2019
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Corresponding Authors:
*shenqiang.hu@sicau.edu.cn; laisj5794@163.com
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