Estrogen receptor 2 mediates intraspecific aggressive behaviors of the female Cricetulus barabensis in the estrous cycle.

The social behavior mechanisms have not been thoroughly reported in the solitary female striped dwarf hamster (Cricetulus barabensis). In this study, the handling bag test and neutral arena measurements were used to detect the changes of aggression in the face of rivals of different genders of wild striped dwarf hamsters. We found that female hamsters had the highest aggressive performance in proestrus, followed by estrus, and the lowest in metestrus and the dioestrus, and the increased aggression during the proestrus or estrus period was low-intensity aggression such as intimidation, shock, boxing and counterattack, or even ritualized non-harmful behaviors to drive away opponents. When confronted with male individuals, aggression in females decreased significantly during estrus. The concentration of plasma estradiol was the highest in estrus and the lowest in metestrus and dioestrus. In contrast, estrogen receptor 2 relative expression in the hypothalamus is the lowest in proestrus and highest in metestrus and dioestrus. Besides, both estradiol levels in plasma and estrogen receptor 2 mRNA in the hypothalamus were associated with aggression. These results will broaden our understanding of the molecular mechanism of how breeding phenotype is an essential driver in changing the social behavior of female Cricetulus barabensis.

Effect of RFRP-3 on reproduction is sex- and developmental status-dependent in the striped hamster (Cricetulus barabensis).

RFamide-related peptides (RFRPs) are orthologous to gonadotropin-inhibitory hormone (GnIH) inhibiting gonadotropin release. There are only two RFRP sequences (RFRP-1 and RFRP-3) encoded in rodents. RFRP-3, which was considered as a hypothetical inhibitor on GnRH, shows a stimulatory effect on the male Syrian and male Siberian hamster in short days. As a dominant rodent pest in northern China farmland, the striped hamster (Cricetulus barabensis) has higher reproductive activities and could act as a model to study the mechanism of reproduction. However, the effect of RFRP-3 on the reproductive activity for the striped hamster is less understood. In the study, we cloned 643 bp RFRP cDNA from the striped hamster hypothalamus, which contained an ORF of 570 bp encoding two RFamide-related peptide (RFRP) sequences: SPAPANKVPHSAANLPLRF-NH2 (C. barabensis RFRP-1) and TLSRVPSLPQRF-NH2 (C. barabensis RFRP-3). We also investigated the expression variation of RFRP mRNA and GnRH mRNA in the hypothalamus from hamsters with different developmental statuses (7-week-, 13-week- and 1.5-year-olds) using FQ-PCR, in which the 13-week-old female individuals were in estrous. The striped hamsters that are 7 weeks and 1.5 years old are non-breeding individuals, and those that are 13-week hamsters have breeding phenomena. The highest hypothalamus RFRP mRNA level was found in breeding males as compared to non-breeding males. Conversely, the lowest RFRP mRNA level in the hypothalamus was observed in breeding females, with no significant level when the breeding females were compared to the 7-week-old individuals. Additionally, the investigation of GnRH expression level showed a declining expression trend across the developmental stages (7-week-, 13-week- and 1.5-year-olds) in both sexes. Significant negative and positive relationships were detected in the 13-week estrous female (r=-0.997, P=0.035) and the 13-week male (r=0.998, P=0.029) striped hamsters respectively, which suggest that RFRP-3 has inhibitory and stimulatory effects on female and male adults respectively. Our results suggest that the effects of RFRP-3 on reproduction are sex- and developmental status-dependent in the striped hamster.

[Comprehensive protocol for diagnosis and treatment of childhood neuroblastoma--results of 45 cases].

OBJECTIVE: The aim of the paper was to improve the prognosis of neuroblastoma (NB) stage III and IV in children through the comprehensive therapy including chemotherapy, delayed tumor resection, autologous stem cell transplantation (ASCT) and inducing differentiation and to analyze the factors affecting the prognosis. METHODS: Newly diagnosed neuroblastoma patients seen from Oct.1998 to Dec.2003 were divided into high, medium and low risk groups depending on clinical stage and age. Comprehensive protocol included accurate staging, delayed and/or second tumor resection for stage III and IV patients, chemotherapy of different intensity mainly composed of cell cycle nonspecific drugs and 13-cis-retinoid for inducing cell differentiation. ASCT was given at the end of therapy for high risk group. RESULT: Forty-five patients, 6 months to 11 years of age, 32 males and 13 females, were analyzed. Of them, 15 were found to have the tumor in adrenal gland, 12 had the tumor extended to the retro-peritoneal space, while in 15 cases the tumor was beside the spinal column in chest and in 3 the tumor was located in other places. Nine cases had stage I, 1 case had stage II, 8 cases had III, 26 cases had stage IV and 1 case had stage IVs of the tumor. Depending on the age and stage of the tumor, 26 cases were aligned into high risk protocol, 10 into medium risk and 9 into low risk groups. Thirty nine cases were treated as planned. Eleven of them received ASCT including 2 cases who received second ASCT. Of the thirty-nine patients, 31 achieved complete remission (CR) and 8 partial remission (PR) after surgery and/or chemotherapy. During up to 21 months median following up period (range 14 to 64 months), 24 cases (62%) kept CR (median 22 months) and 4 survived with stable disease. The survival rate (SR) was 72%. Eleven cases died of relapse and disease progression. No death occurred from treatment complication. Statistical analysis showed that the age older than 18 months, and stage III and IV of the tumor were the factors predicting poor prognosis (P = 0.04 and 0.003, respectively). Patients who had the tumor originated from the retroperitoneal space, who had incomplete tumor resection, and those who did not receive ASCT had poorer prognosis, but the differences were not significant (P = 0.092, 0.55 and 0.60, respectively). CONCLUSION: The comprehensive protocol seemed to be reasonable. Age older than 18 months, and stage III and IV were the factors suggesting poor prognosis. The origin of the tumor, completeness of tumor resection, and use of ASCT had no significant impact on the prognosis.