Effects of flavonoids from Semen Cuscutae on the reproductive system in male rats

AIM

To evaluate the effects of the flavonoids extracted from the Semen Cuscutae (FSC) on the reproductive and endocrine functions in male rats.

METHODS

(1) FSC were obtained from the semen of Cuscuta sinensis Lam through solvent extraction and polyamide columnar chromatography; (2) Effect of FSC on the reproductive organs was assessed in immature rats. Rats were administered FSC through gastric gavage at a dose of 300 mg/kg per day for 7 days and the weights of testis, epididymis, seminal vesicle and pituitary gland were then observed; (3) To observe the effect of FSC on the reproductive endocrine function: same dose level of FSC was given to male rats of different age groups for 7 days; on day 8, the plasma testosterone (T), estradiol (E2) and LH were determined by RIA, the specific binding of LH was estimated and the testes were weighed. (4) Effect of FSC on LH secretion was assessed in vitro on cultured adenohypophysis. (5) Effect of FSC on T secretion was assessed in vitro on Leydig cell culture.

RESULTS

FSC increased the weights of testis, epididymis and pituitary gland, and stimulated T and LH secretion both in vitro and in immature rats.

CONCLUSION

FSC invigorates the reproductive system and reproductive endocrine function in male rats.

The Gas7 gene encodes two protein isoforms differentially expressed within the brain

Gas7, a growth arrest-specific gene first isolated from serum-starved NIH3T3 cells, is expressed abundantly in the brain and is essential for the outgrowth of neurites from cultured cerebellar neurons. Here, we report the existence of a Gas7-related cDNA, designated Gas7-cb, isolated from the mouse cerebellum, and we report the finding that Gas7-cb transcripts and protein are expressed at different locations than those of Gas7. Gas7-cb cDNA differs from the Gas7 cDNA only in the 5' region. Its encoded protein shares the same 320 amino acids in its C-terminus with those of Gas7. Analyses of the RNA and protein expression of Gas7-cb and Gas7 by RNase protection assay and Western blot indicated that while Gas7 expression is predominant in the cerebrum and in growth-arrested NIH3T3 fibroblasts, Gas7-cb expression is predominant in the cerebellum. Characterization of Gas7 and Gas7-cb RNAs and of the genomic structure of murine Gas7 cloned in a bacterial artificial chromosome indicated that the Gas7 gene spans more than 60 kb and consists of at least 15 exons. The 5'-terminus of Gas7-cb is located at exon 6a, which is absent in Gas7 transcripts but is retained in its entirety in Gas7-cb transcripts, resulting in the presence of a unique 20-amino-acid sequence at the N-terminus of the Gas7-cb protein. Our results show that the Gas7 gene encodes two Gas7 isoforms, Gas7 and Gas7-cb, whose expression is differentially regulated within mouse brain.

gas7: A gene expressed preferentially in growth-arrested fibroblasts and terminally differentiated Purkinje neurons affects neurite formation

Growth arrest-specific (gas) genes are expressed preferentially in cells that enter a quiescent state. gas7, which we identified in serum-starved murine fibroblasts, is reported here to be expressed in vivo selectively in neuronal cells of the mature cerebral cortex, hippocampus, and cerebellum. gas7 transcripts encode a 48-kDa protein containing a structural domain that resembles sequences of OCT2, a POU transcription factor implicated in neuronal development, and synapsins, which have a role in modulating neurotransmitter release. Using in situ hybridization and immunocytochemical analysis, we show that GAS7 expression occurs prominently in cerebellar Purkinje cells and that inhibition of production in terminally differentiating cultures of embryonic murine cerebellum impedes neurite outgrowth from maturing Purkinje cells. Conversely, GAS7 overexpression in undifferentiated neuroblastoma cell cultures dramatically promotes neurite-like outgrowth. Collectively, our results provide evidence for an association between expression of this gas gene and neuronal development.

Identification of the cis-elements required for transcriptional control of the Chinese hamster ovary APRT gene

Transcriptional regulation of the Chinese hamster ovary (CHO) adenine phosphoribosyltransferase-encoding gene (APRT) was studied. The 5' region of the CHO APRT is G + C-rich, but lacking TATA or CCAAT boxes. RNase protection assays indicate that it contains multiple transcription start points (tsp). A tsp 64 bp upstream from the translation start codon is denoted as +1. Linker-scanning (LS) mutation analysis indicates that the -33 to +19 region is important in regulating APRT transcription. Mutations in the -23 to -14 region abolish transcription initiated from the -23 downstream region. An unidentified protein complex binds to this region. Three Sp1-binding sites are found in the APRT promoter; however, mutations of the Sp1-binding sites do not reduce APRT transcription. Mutations at two putative GCF-binding sites increase levels of transcription.

Modulation of APRT transcription by altering spacing between cis-regulatory elements

Three regulatory regions on the promoter of CHO adenine phosphoribosyltransferase gene (APRT) were identified. Spacing constraints between these regions were analyzed. With normal spacing, region II (-33 to +19), which separates regions I (-101 to -53) and III (+56 to +85), is critical for APRT transcription. However, when regions I and III are artificially placed in proximity to each other (region II deleted), they are able to drive transcription as efficiently as the wild-type APRT promoter. Neither region I nor III alone is sufficient for efficient transcription. As the spacing between the two regions increases, the transcription decreases. Region I may activate transcription in two ways: through a stringent sequence-specific manner (as in the transcription mediated by regions I and III) and through a manner with relaxed requirement for sequence specificity (as in the transcription from the wild-type APRT promoter).