1 Introduction

2 Materials and methods

2.1 Drug preparation

The mature seeds of Cuscuta sinensis Lam were dried and powdered, and were then extracted with 75% alcohol under reflux. The extract was concentrated and subjected to columnar chromatography on polyamide, which was eluted successively with alcohol and petroleum ether to yield the total flavonoids, the retrieval rate being 0.5%. Thin layer chromatography showed that the extract mainly contained four components: quercetin, astragalin, hyperoside and quercetin-3-o-glucose, which were identical with those reported in the literature^[6]. In the present study, FSC was prepared at a concentration of 10 g/L. Rats were treated with FSC at a dose of 150 mg/kg body weight through gastric gavage bid.   

2.2  Animals

Healthy SD rats of different age groups were obtained from the Experimental Animal Centre of our Medical School. They were housed under standard conditions in a controlled environment with a 12-h photoperiod and had free access to food and water.

2.3  Hormone determination

Testosterone (T) and estradiol (E₂) were determined by RIA, and LH by radio-receptor assay (RRA)^[9]. The RIA kits and ¹²⁵I-hCG were provided by the Shanghai Institute of Biological Products.

2.4 Assessment of effect of FSC on reproductive organs

Sixty immature male SD rats, 50-60 days old (60-80 g), were divided randomly into 3 groups of 20 rats each. To the first group, FSC was administered through gastric gavage at a dose of 300 mg/kg per day. To the second group, hCG was administered im at a dose of 5 IU/rat per day. To the third group (control) a similar volume of physiological saline was given orally. The drugs were administered consecutively for 7 days and on the 8th day, the animals were sacrificed and the weights of the testis, epididymis, seminal vesicles and pituitary gland were observed.

2.5  Assessment of effect of FSC on reproductive endocrine function

Male SD rats at the age of 2 months (75-85 g), 10 months (200-250 g), 18 months (250-350 g) and 24 months (250-350 g) were used in this experiment. The rats from each age group were randomly divided into 2 groups: treatment and control. To the treatment group FSC was administered at a dose similar as in the above experiment and to the control group equal volume of physiological saline was administered. On the 8th day, the animals were sacrificed and blood was obtained from the abdominal aorta. Plasma samples were prepared for T, E₂ and LH determination. Testes were weighed and the specific binding of hCG to testis (in pg hCG/10 mg testis) was determined according to the method of Frowein and Engel^[11].

2.6  Effect of FSC on LH production in vitro

The experiment was performed according to the method of Lee et al^[12] fly, 30 pituitary glands were obtained from adult male SD rats and were immediately preserved in frozen PBS. The adenohypophyses were then divided into two parts along the midline and were grouped by pair-matched design. One part was used as the control and the other treated as follows: (1) FSC group: 200 g FSC and 1 mL M199 (Sigma, USA) were added; (2) GnRH group: 1 g of GnRH (Shanghai Institute of Biochemistry, The Chinese Academy of Science ) and 1 mL M199 were added; (3) GnRH+FSC group: both reagents and 1 mL M199 were added; to the 3 control groups, only M199 was added. These groups were then cultured at 37 for 4 hours in an atmosphere of 95% O₂ and 5% CO₂. Thereafter LH concentrations were assayed in the media.

2.7   Effect of FSC on T production in vitro

Leydig cell suspension was prepared from SD rats according to the method of Kinefelter^[13] with a final concentration of 110⁶ cells/mL M199. Four groups were constituted: (1) FSC group: to this group 200 g FSC and 1 mL M199 were added; (2) hCG group: 5 IU hCG (Calbiochem-Behring Grop, USA) and 1 mL M199 were added; (3) FSC+hCG group: both reagents and 1 mL M199 were added; (4) Control: 1 mL M199 was added. These groups were then cultured at 37 for 3 hours in an atmosphere of 95% O₂ and 5% CO₂ shaking at 90 times/min. Thereafer T concentrations were assayed in the media.

2.8 Statistical analysis

3 Results

3.1  Effect of FSC on reproductive organs

As can be seen from Table 1, FSC stimulated the development of reproductive organs in immature male rats. The weights of the pituitary gland, testis and epididymis were significantly increased upon FSC administration. hCG increased the weights of testis, epididymis and seminal vesicles, but not the pituitary glands.

Table 1. Effect of FSC on reproductive organs. ^bP<0.05, ^cP<0.01, vs control. n=20. means.

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