Question

1. Describe the mechanism by which the male contraceptive pill would work (include details of where and how in the body it will produce its effects)
2. How might it impact the hormonal pathways involved? What structure and process might be involved?

Answer 1

Answer:

1. Despite many years of research, the prospects for finding a safe, effective male contraceptive pill remain dim. One of the basic problems is that the mechanisms that lead to sperm production in a man are closely linked to the mechanisms for sex drive and sex potency. As a result, drugs that interfere with a man's desire or ability to have sexual intercourse in the first place.

Complicating matters further is the fundamental truth that it is ultimately the woman who gets pregnant. The motivation in most men to use contraception or risk its side effects is therefore not comparable to most women's. This means that even if and when an effective male contraceptive becomes available, most womwn would be able to rely on it only in close and trusting relationships.

One way researchers have tried to inhibit sperm production (spermatogenesis) is to give injections of the hormone testosterone. Large amounts of this androgenizing hormone inhibit the secretion of follicle stimulating hormone and luteinizing hormone from the pituitary gland, which is turn inhibits spermatogenesis. The many variations on this approach seem to block sperm production completely in some men but not in all.

An alternative approach involves taking testosterone together with drugs called gonadotropin releasing hormone (GnRH), agonists, which suppress the secretion of luteinizing hormone and follicle stimulating hormone. This approach seems to be more effective in bringing the sperm count down to zero. But because this method requires daily injections, it is impartical. On top of that, it often leads to unacceptable side effects, including blood clots,an enlarged prostate gland, and changes in blood lipoprotein levels.

2. Hormones mediate changes in target cells by binding to specific hormone receptors. In this way, even though hormones circulate throughout the body and come into contact with many different cell types, they only affect cells that possess the necessary receptors. Receptors for a specific hormone may be found on many different cells or may be limited to a small number of specialized cells. For example, thyroid hormones act on many different tissue types, stimulating metabolic activity throughout the body. Cells can have many receptors for the same hormone, but often also possess receptors for different types of hormones.

The number of receptors that respond to a hormone determines the cell’s sensitivity to that hormone and the resulting cellular response. Additionally, the number of receptors that respond to a hormone can change over time, resulting in increased or decreased cell sensitivity. In up-regulation, the number of receptors increases in response to rising hormone levels, making the cell more sensitive to the hormone, allowing for more cellular activity. When the number of receptors decreases in response to rising hormone levels, called down-regulation, cellular activity is reduced.

Cells respond to a hormone when they express a specific receptor for that hormone. The hormone binds to the receptor protein, resulting in the activation of a signal transduction mechanism that ultimately leads to cell type-specific responses. Receptor binding alters cellular activity, resulting in an increase or decrease in normal body processes. Depending on the location of the protein receptor on the target cell and the chemical structure of the hormone, hormones can mediate changes directly by binding to intracellular hormone receptors and modulating gene transcription, or indirectly by binding to cell surface receptors and stimulating signaling pathways.

Hormone functioning: The hormone insulin binds to its receptor (1), which starts many protein activation cascades (2). These include translocation of Glut-4 transporter to the plasma membrane and influx of glucose (3), glycogen synthesis (4), glycolysis (5), and triglyceride (6).