Related Experiment Video
Updated: Feb 17, 2026
Dissection of Larval Zebrafish Gonadal Tissue
Published on: April 26, 2017
Fertility impairment with defective spermatogenesis and steroidogenesis in male zebrafish lacking androgen receptor
Haipei Tang1, Yu Chen1, Le Wang1
1State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals and Guangdong Provincial Key Laboratory of Improved Variety Reproduction in Aquatic Economic Animals, School of Life Sciences, Sun Yat-Sen University, Guangzhou, China.
Abstract:
The pivotal role of androgen receptor (AR) in regulating male fertility has attracted much research attention in the past two decades. Previous studies have shown that total AR knockout would lead to incomplete spermatogenesis and lowered serum testosterone levels in mice, resulting in azoospermia and infertility. However, the precise physiological role of ar in controlling fertility of male fish is still poorly understood. In this study, we have established an ar knockout zebrafish line by transcription activator-like effectors nucleases. Homozygous ar mutant male fish with smaller testis size were found to be infertile when tested by natural mating. Intriguingly, a small amount of mature spermatozoa was observed in the ar mutant fish. These mature spermatozoa could fertilize healthy oocytes, albeit with a lower fertilization rate, by in vitro fertilization. Moreover, the expression levels of most steroidogenic genes in the testes were significantly elevated in the ar mutants. In contrast, the levels of estradiol and 11-ketotestosterone (11-KT) were significantly decreased in the ar mutants, indicating that steroidogenesis was defective in the mutants. Furthermore, the protein level of LHβ in the serum decreased markedly in the ar mutants when compared with wild-type fish, probably due to the positive feedback from the diminished steroid hormone levels.
Insights
Male zebrafish lacking the androgen receptor (AR) are infertile, despite producing some sperm. This study reveals AR
Area of Science:
- Reproductive Biology
- Endocrinology
- Genetics
Background:
- The androgen receptor (AR) is crucial for male fertility, but its specific role in fish reproduction is unclear.
- Previous studies in mice show AR knockout causes infertility and low testosterone.
- Understanding AR's function in fish can provide insights into vertebrate reproductive health.
Purpose of the Study:
- To investigate the physiological role of the androgen receptor (AR) in male zebrafish fertility.
- To establish and characterize an AR knockout zebrafish model.
- To elucidate the effects of AR deficiency on spermatogenesis and hormone levels in fish.
Main Methods:
- Generated an AR knockout zebrafish line using transcription activator-like effectors nucleases (TALENs).
- Assessed fertility through natural mating and in vitro fertilization (IVF) assays.
- Quantified testis size, sperm production, and fertilization rates.
- Measured gene expression of steroidogenic enzymes and hormone levels (estradiol, 11-ketotestosterone, LHβ).
Main Results:
- Homozygous AR mutant male zebrafish exhibited smaller testes and were infertile via natural mating.
- AR mutant fish produced a limited amount of mature spermatozoa capable of fertilization in vitro, but with reduced efficiency.
- Steroidogenic gene expression in testes was upregulated, while estradiol and 11-ketotestosterone levels were significantly decreased.
- Serum LHβ protein levels were markedly reduced in AR mutants compared to wild-type fish.
Conclusions:
- The androgen receptor (AR) is essential for male fertility in zebrafish, impacting spermatogenesis and hormone regulation.
- AR deficiency leads to defective steroidogenesis and reduced levels of key reproductive hormones, affecting fertility.
- The AR knockout zebrafish model provides a valuable tool for studying male reproductive endocrinology and infertility.
Related Concept Videos
01:23Infertility in Males
01:41Spermatogenesis