The spermatogenesis is the process by which spermatozoa are generated in the testes. The spermatozoa travel male reproductive tract during which they meet many substances secreted from reproductive organs. One of the substances is epididymal protease inhibitor (EPPIN) that is involved in the post-testicular maturation including capability of fertilizing the eggs. The expression of EPPIN gene was investigated in various tissues of sexually mature and regressed male Syrian hamsters by reverse transcription polymerase chain reaction (RT-PCR). The EPPIN gene was identified in the testis and epididymis of the male Syrian hamsters and compared to the genes reported previously. There was no expression of EPPIN gene in reproductively and completely regressed testes of Syrian hamster. These results suggest that the expressions of the EPPIN gene are associated with the reproductive capability in the Syrian hamsters.

GnRH (gonadotropin-releasing hormone) is a supreme hormone regulating reproductive activity in most animals. The sequences of amino acid and nucleic acid of GnRH reported up to now are examined from the evolutionary framework of Chordata. All identified GnRH are classified into GnRH1, GnRH2, or GnRH3. In all three forms of GnRH both N-terminal and C-terminal are conserved, which allows for effective binding to their receptors. The three amino acids in the middle of GnRH1 sequence have altered diversely from the primitive Chordata, which is indicative of the adaptation process to the ambient environment. GnRH2 and GnRH3 sequences are well conserved. There are more diverse modifications in the nucleic acids than in amino acid sequence of GnRH1. These variations can result from meiosis, mutation, or epigenetics and indicate that GnRH is the product of natural selection.

In the published article “Bitter melon extract does not alter photoperiodic effects on reproduction of male golden hamsters. Dev. Reprod. 2017; 21(2):215-221. https://doi.org/10.12717/DR.2017.21.2.215,” the corresponding author’s name is given incorrectly. The Editorial Office of Korean Society of Developmental Biology would like to correct the corresponding author’s name. The Editorial Office apologizes for any inconvenience that it may have caused.

Bisphenol-A(BPA) is a member of alkylphenol family, and shows adverse effects including reduced fertility, reproductive tract abnormalities, metabolic disorder, cancer induction, neurotoxicity and immunotoxicity. In the present study, we conducted Hershberger assay to evaluate whether the two candidates to replace BPA have androgenic or antiandrogenic activity. The assay was carried out using immature castrated Sprague–Dawley male rats. After 7 days of the surgery, testosterone propionate (TP, 0.4 mg/kg/day) and test materials (low dose, 40 mg/kg/day; high dose, 400 mg/kg/day) were administered for 10 consecutive days by subcutaneous (s.c.) injection and oral gavage, respectively. Test materials were BPA, isosorbide (ISO) and cyclohexanedimethanol (CHDM). The rats were necropsied, and then the weights of five androgen-dependent tissues [ventral prostate, seminal vesicle, levator ani-bulbocavernosus (LABC) muscle, paired Cowper’s glands, and glans penis] and three androgen-insensitive tissues (kidney, spleen and liver) were measured. All test materials including BPA did not exhibit any androgenic activity in the assay. On the contrary, antiandrogen-like activities were found in all test groups, and the order of the intensity was CHDM > BPA > ISO in the five androgen-sensitive tissues. There was no statistical difference between low dose treatment and high dose treatment of BPA group as well as ISO group. In CHDM group, high dose treatment exhibited most severe weight reduction in all measured tissues. There was no statistical difference in androgen-insensitive tissue measurements, except BPA groups. Since the effects of ISO treatment on the accessory sex organs were much less or not present at all when compared to those of BPA, ISO could be a strong candidate to replace BPA. CHDM treatment brought most severe weight reduction in all of androgen-sensitive tissues, so this material should be excluded for further screening of BPA substitute selection.

Bitter melon (Momordica charantia, MC) has been used in traditional Korean medicine in treating diabetes. In addition, some reports were emerged, showing the antifertility activities of MC in mammals. We investigated the effects of ethanolic MC extract on the reproductive activity of golden hamsters whose spermatogenetic capacity is controlled by their photoperiods. The animals were divided into 4 groups: long photoperiod (LP) control, short photoperiod (SP) control, and LP animals treated with MC. The animals were orally ingested with low (0.03 g/kg) or high (0.15 g/kg) concentrations of the ethanolic extracts for 8 weeks on the daily basis. The control animals received the vehicle. The animals were then mated with age-matched females, experienced pregnancy. As results, the LP control animals showed active large testes but SP control animals displayed remarkably reduced testes. The animals treated with both concentrations of MC extracts demonstrated large testes, indicating fertile activity as animals in LP. LP control animals had litters as expected, but SP controls had no litters at all. MC extract showed the same results as LP animals in generating offsprings. These results suggest that the MC extract does not change the photoperiodic influence on reproductive activity of male golden hamsters.

The flower buds of Syzygium aromaticum (clove) have been used as traditional medicine for the treatment of male sexual disorders in Asian countries. Recently, there are some reports about the effects of the clove on reproductive activities in mammals. Therefore, its effect on testicular function was examined in male golden hamsters whose reproductive activity is inhibited by photoperiod such as winter climate. The male animals were given by daily oral administrations (56 consecutive days) in three doses (4 mg, 20 mg, and 100 mg/kg BW) of the alcoholic extract of the clove. Generally lower dose (4 mg) of the extract continued to keep the reproductive activities of testes. The both middle and high doses (20 mg and 100 mg) of the extract completely inhibited the testicular activity in some animals. Taken together, these results suggest a possible biphasic action of alcoholic extract of Syzygium aromaticum flower bud on testicular function.

Living beings are surrounded by various changes exhibiting periodical rhythms in environment. The environmental changes are imprinted in organisms in various pattern. The phenomena are believed to match the external signal with organisms in order to increase their survival rate. The signals are categorized into circadian, seasonal, and annual cycles. Among the cycles, the circadian rhythm is regarded as the most important factor because its periodicity is in harmony with the levels of melatonin secreted from pineal gland. Melatonin is produced by the absence of light and its presence displays darkness. Melatonin plays various roles in creatures. Therefore, this review is to introduce the diverse potential ability of melatonin in manifold aspects in living organism.

Golden hamsters are seasonal breeders whose reproductive activities are active during summer. Their sexual function is completely suppressed in winter. In oriental society, traditional medicines have been utilized in treating various complaints. One of them is Cynomorium songaricum (CS) whose extract has been used in treating male impotence and sexual dysfunction. We investigated the effects of aqueous CS extract on the process of spermatogenesis in golden hamsters. The animals were divided into 4 groups: long photoperiod (LP) control, short photoperiod (SP) control, and SP animals treated with low or high concentrations of CS. The animals were daily intubated with low (1.25 g/kg) or high (2.50 g/kg) concentrations of the CS aqueous extracts for 8 weeks. The control animals received the vehicle. The volume of testis was measured consecutively from the same animal at 4 week intervals. As results, the LP control animals showed large testes that indicate reproductively active function, but SP control animals displayed remarkably reduced testes that reflect inactive function. The outcomes of the reproductive activity from low concentrations of CS were not conspicuous. And the integral consequences of the reproductive activity from high concentrations of CS treatments were not significant either. But in tracing the individual animals treated with high CS extract, the effects were evidently splitted into dichotomy. In one subgroup small testes were displayed as in SP control animals, but in the other subgroup large testes were demonstrated as in LP control animals, which implies the absolute prevention of regressing activity by SP. These results suggest that the CS extract has a potency to prevent the regressing effects of SP and promotes the male fertility by strengthening the spermatogenesis in the golden hamsters.

Golden hamsters reproduce in a limited time of a year. Their sexual activities are active in summer but inactive in winter during which day length does not exceed night time and environmental conditions are severe to them. The reproductive activities are determined by the length of light in a day (photoperiod). Melatonin is synthesized and secreted only at night time from the pineal gland. Duration of elevated melatonin is longer in winter than summer, resulting in gonadal regression. The present study aimed at the influences of continuous melatonin treatments impinging on the gonadal function in male golden hamsters. Animals received empty or melatonin-filled capsules for 10 weeks. They were divided into long photoperiod (LP) and short photoperiod (SP). All the animals maintained in LP (either empty or melatonin-filled capsules) showed large testes, implying that melatonin had no effects on testicular functions. Animals housed in SP displayed completely regressed testes. But animals kept in SP and implanted with melatonin capsules exhibited blockage of full regression by SP. These results suggest that constant release of melatonin prohibits the regressing influence of SP.

The reproductive activity in male mammals is well known to be regulated by the hypothalamus-pituitary-gonad axis. The hypothalamic neurons secreting gonadotropin releasing hormone (GnRH) govern the reproductive neuroendocrine system by integrating all the exogenous information impinging on themselves. The GnRH synthesized and released from the hypothalamus arrives at the anterior pituitary through the portal vessels, provoking the production of the gonadotropins(follicle-stimulating hormone (FSH) and luteinizing hormone (LH)) at the same time. The gonadotropins affect the gonads to promote spermatogenesis and to secret testosterone. Testosterone acts on the GnRH neurons by a feedback loop through the circulatory system, resulting in the balance of all the hormones by regulating reproductive activities. These hormones exert their effects by acting on their own receptors, which are included in the signal transduction pathways as well. Unexpected aberrants are arised during this course of action of each hormone. This review summarizes these abnormal phenomena, including various mutations of molecules and their actions related to the reproductive function.

플라스틱 가소제인 di(2-ethylhexyl)phthalate (DEHP)는 매우 잘 알려진 내분비계 장애물질(endocrine disrupting chemicals; EDCs) 중 하나로, 수컷 설취류와 인간의 생식과 발생 과정에 있어 강력한 항안드로겐성 작용을 하는 것으로 알려져 있다. 본 연구는 사춘기 이전에 수컷 흰쥐를 DEHP에 노출시킴으로써 부속 성기관의 성숙 과정 동안 나타나는 변화를 조사한 것이다. 결과로, DEHP 투여에 의한 체중, 혈중 T 수준, 저정낭과 전립선을 제외한 조직의 무게는 대조군과 비교하여 유의적인 변화가 없었다. 저정낭의 경우, 고농도(200 ㎎/㎏)의 DEHP를 처리한 투여군의 무게가 대조군에 비해 유의하게 감소하였으며(p<0.05), 전립선의 경우, 저농도(20 ㎎/㎏)와 고농도의 DEHP를 처리한 모든 투여군에서 대조군에 비해 유의한 무게의 감소를 나타내었다(p<0.05). 조직학적 연구 결과, DEHP 투여군의 저정낭은 대조군에 비해 점막층의 면적이 감소하였다. 또한, 전립선의 경우 대조군에서는 분비상피세포들이 입방형인데 비해 DEHP 투여군에서는 위중층상피세포 형태가 관찰되었다. 정량적 RT-PCR 연구에서, 저정낭에서의 ER-α 발현은 고농도 DEHP 투여에 의해 유의한 발현 증가가 나타났으며(p<0.05), ER-β의 경우 저농도 DEHP 투여에 의해 유의한 발현 감소가 나타났다(p<0.05). 전립선에서의 ER-β 수준은 저농도 DEHP 투여에 의해 유의하게 감소하나(p<0.05), 고농도 DEHP 투여에 의해서는 유의한 발현 증가가 나타났다(p<0.01). 그러나 AR 발현의 경우, 저정낭과 전립선 모두에서 DEHP에 의해 유의한 차이가 나타나지 않았다. 결론적으로, 본 연구는 (i) DEHP의 유해한 작용이 사춘기 이전 시기의 성적인 성숙을 교란할 수 있으며, (ii)저정낭과 전립선이 사춘기 이전 시기 DEHP 노출에 대한 민감한 표적이 될 수 있고, (iii) DEHP의 유해한 작용이 ER과 연관된 기작을 통해 매개될 수 있음을 시사한다.