Effect of Popular Herbicide on Rats Shows it Can Disturb Hormonal Balance

A group from the Indian Institute of Science (IISc), Bengaluru, has tested the effects of a commonly used herbicide named Roundup on hormonal balance in rats.

In a recently published paper in the journal Toxicology Reports, Prof Medhamurthy Rudraiah at MRDG, IISC, and his student Aparamita Pandey say that Roundup can cause imbalances in the synthesis of steroid hormones in male rats.

Roundup, sold by Monsanto, is an extensively used herbicide. It kills weeds by inhibiting enzymes that synthesise aromatic amino acids (the basic building blocks that make up proteins) essential for plant development.

Humans and most mammals do not have the enzymes for and therefore cannot synthesise these aromatic amino acids, which is why Roundup is considered to be safe and non-toxic. Recent studies, however, have suggested that Glyphosate, the primary constituent of Roundup could be a carcinogen, and could affect the development of foetus and disrupt hormonal function.

Roundup exposure at a dose as low as 10 mg per kg body weight of rats causes decrease in testosterone and corticosterone secretions. The study revealed that the effects of Roundup seem to be caused by a decrease in the synthesis or release of the hormone ACTH (Adreno-Cortico-Tropic Hormone) from the pituitary gland. Without ACTH, the adrenal glands are not able to stimulate corticosterone hormone production. When rats exposed to Roundup were injected with ACTH preparation, the deficiency of corticosterone was overcome.

Company Will Study Report

Arun Gopalakrishnan of Public Affairs in Monsanto, told Express, “Unless we have a chance to study the report in detail, it would not be fair for us to comment. We will study the report in detail.”

The current study draws a parallel between the observed effects of Roundup treatment in rats to ‘adrenal insufficiency’ in humans. Adrenal insufficiency is caused by abnormally low levels of cortisol that lead to fatigue, anorexia, sweating, anxiety, shaking, nausea, heart palpitations and weight loss; chronic cases of which can be fatal, if untreated.

In males, the majority of steroid hormones are secreted by testis and the adrenal gland (hormone producing gland situated just above the kidneys). The corticosteroid hormones from the adrenal glands are vital not only for maintaining normal glucose and fat metabolism, but also for mineral balance in the body.

The male hormone, testosterone, secreted from testis is essential for sexual functions. Secretion of corticosteroids and testosterone are controlled by the pituitary or ‘master gland’ that is found in the brain.

“It is therefore highly possible that Roundup affects other endocrine glands as well,” says Aparamita, first author of the study.

“In this study, we treated mice with Roundup for only two weeks and we see such clear effects. Further investigations on longer exposure times should now be done as this weed killer is extensively used and humans are potentially exposed to it,” she adds.