Human chorionic gonadotropin (HCG) is a hormone that was originally recognized because of its role in reproduction. HCG and the pituitary hormones follitropin (FSH), lutropin (LH), and thyrotropin (TSH) make up the glycoprotein hormone group.
HCG is synthesized not just by the placenta but also by a range of tumors. Synthesis begins at the very early phase of pregnancy. HCG is released by the blastocytes on the 7th day and, after successful implantation, the placenta begins to manufacture and secrete massive quantities of HCG into the bloodstream. HCG biosynthesis reaches its peak as gestation enters its 11th week, starts waning as it approaches the 12th week, and is maintained at low levels for the rest of the pregnancy. HCG is present in the serum and urine of pregnant women.
The existence of cyclic HCG or LH receptors in the womb implies that these hormones exercise regulatory control over uterine functions. Studies have correlated low HCG levels and reduced uterine vascular resistance in pregnant women.
Another aspect of HCG that has generated excitement among scientific circles is the apparent potential of this hormone to prevent or control cancer. Clinical studies involving mice showed that injection of purified HCG elevated apoptosis rate in breast cancer xenographs. These results correlate to other clinical findings that exposure to purified HCG diminishes cellular viability in several breast cancer cell lines. The effects of HCG in cell viability seems to be associated with the expression or activation of HCG/LH receptor. Further studies and tests to explore the apoptotic effect of HCG may yet enhance control or treatment of advanced breast cancer in therapies combining HCG injections with chemotherapy or localized treatment.
A deeper understanding of HCG’s configuration might yield relevant information that could lead to breakthroughs in vaccine development. Two structures of HCG have been analyzed, revealing that HCG belongs to the family of cysteine knot growth factors along with other proteins like platelet-derived growth factor (PDGF) and transforming growth factor-beta (TGF_beta).
A 37-amino acid peptide makes up the carboxyl terminus of HCG’s beta subunit. This arrangement is unique to HCG and not manifested in other glycoproteins. This is remarkable because 10 of the 37 residues of the amino acids are proline.
The effects of HCG on nitric oxide (NO) synthesis has been explored by researchers for decades. Presently, the physiological role of HCG on NO synthesis is yet to be fully identified. However, since NO has surfaced as a significant intercellular and intracellular regulatory molecule with functions as varied as neural exchange, host defense, and cell growth management, it’s quite easy to hypothesize on its involvement in the local regulation of various basic processes. Moreover, it has been shown that NO may perform a major role in the management of inter-alpha-trypsin inhibitor protein’s intrafollicular influx and in ovulation.
Down syndrome (DS) is a genetic abnormality that is strongly related to human chorionic gonadotropin. More discoveries on functional and structural relationships could be used to detect and possibly cure this genetic disorder. An earlier diagnosis of Down syndrome would be desirable for any form of intervention to work. Some analytes have been identified in the serum of pregnant women whose fetuses are afflicted with Down syndrome.
In the past decades, a huge number of scientific experiments have been conducted by various researchers to dig deeper into the nature and structure of this pregnancy hormone. It has been proven in so many ways that HCG has a strong link and influence on critical physiological and biological functions of the human body like blood circulation, treatment of cancer cells, and genetic disorders like Down syndrome and so on.Continue reading