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Nature’s Viagra? Deadly Spider Venom Gives 4-Hour Erections

The bite of the Brazilian wandering spider gives male victims long-lasting erections.

The bite of the Brazilian wandering spider gives male victims long-lasting erections.

Webster’s New World College Dictionary defines “serendipity” as “luck, or good fortune, in finding something good accidentally.” It’s doubtful, however, that the first man to discover the erection-friendly side effects of a potentially fatal spider bite considered his find to have been that serendipitous.

It turns out that the ultra-toxic bite of the Brazilian wandering spider, known scientifically as Phoneutria nigriventer, can leave its male victims with what London’s Daily Mirror describes as “a stonking four-hour erection.” Of course, other effects of the spider’s venom are far less welcome. These include intense pain at the bite site, an elevated heart rate, profound shortness of breath, excessive salivation, and, in rare cases, death.

Active Compound Isolated

Given these other adverse effects, it’s a fairly sure bet that no man would willingly subject himself to the spider’s bite just for its boost to his erectile function. Thanks to modern medical science, the compound responsible for the venom’s erectile effects has been isolated and successfully tested in animal models of impotence. Further testing may eventually lead to yet another form of treatment for erectile dysfunction. However, it is unlikely that such a new drug will be available any time soon.

Considering the widespread incidence of erection problems among American men, finding a market for such a drug should hardly pose a problem. According to an article posted at Wired.com, ED affects roughly 10 percent of men in every decade of life, meaning that roughly 40 percent of men in their 40s have at least occasional difficulty in getting and/or keeping an erection.

Erection-Friendly Peptide

Scientists have identified a peptide in the spider’s venom that is responsible for the erection-friendly effects of the spider’s bite. Labeled PnTx2-6, the compound has been confirmed as a biological version of Viagra, the PDE5 inhibitor that has revolutionized the treatment of ED since its introduction in the late 1990s.

Although scientists have known for more than a decade that PnTx2-6 has erection-boosting properties, the challenge has been to find a way to produce the compound in sufficient quantities to make it commercially viable. However, setting up a large-scale wandering spider farm to harvest the venom would not be a viable proposition.

"Wow!! Was it a spider bite or is he just happy to see me?"

“Wow!! Was it a spider bite or is he just happy to see me?”

In 2014, scientists came up with a process to replicate the PnTx2-6 peptide. They created a recombinant baculovirus using the PnTx2-6 gene. They then used the virus to infect a culture of caterpillar cells, which then produced the peptide in sufficient quantities for animal testing.

South Korean Study

To test its erectile properties, South Korean researchers injected the PnTx2-6 peptide into the intracavernosal tissue of laboratory rats in which bilateral cavernous nerve crush injury (BCNI) had been simulated. The cavernous nerves are located in the corpora cavernosa — twin columns of spongy erectile tissue in the penis — and facilitate the erectile process. Some rats with these injuries were left untreated.

The injections of PnTx2-6 were made three times a week across a four-week period. At the conclusion of this test period, the rats were tested to determine the level of blood flow within the erectile tissue of the penis. They were also tested to determine levels of nitric oxide and cyclic guanosine monophosphate, or cGMP. Both these compounds play key roles in erectile function in all mammals.

Positive Findings

Rats that had been injected with the PnTx2-6 peptide showed significantly higher blood flow within the erectile tissue of the penis than rats that had not been treated with PnTx2-6. And rats treated with the peptide also showed higher levels of nitric oxide and cGMP.

In the conclusion to their study, which was published in the September 2014 issue of “Urology,” the South Koreans state that treatment with PnTx2-6 “improved erectile function and prevented muscle atrophy in a rat model of BCNI via increased synthesis of nitric oxide and cyclic guanosine monophosphate.”

All of which means that this compound isolated from a spider’s venom may someday help men overcome erectile dysfunction. However, in the meantime, much work must be done to find even better ways of replicating the peptide on a large scale. And, most importantly, it must be subjected to testing with human subjects.

Nitric Oxide, cGMP

The increase in penile levels of nitric oxide and cGMP are significant to anyone familiar with the basic mechanics of erection in human males. The erection process begins with feelings of sexual desire in the brain, which trigger a release of nitric oxide that is sent flooding into the pelvic region. This surge of nitric oxide sets off secondary chemical reactions, one of which gives rise to a compound known as cyclic guanosine monophosphate, or cGMP.

Scientists have identified a peptide in the spider's venom that may someday form the basis for a new impotence drug.

Scientists have identified a peptide in the spider’s venom that may someday form the basis for a new impotence drug.

The smooth muscles of the blood vessels that supply the penis relax in response to increased local levels of cGMP. As the blood vessels relax, fresh blood surges into the penis, filling its spongy erectile tissue and creating an erection.

Viagra and the other drugs in its family — known collectively as PDE5 inhibitors — help men with diminished blood flow to the penis to get and keep erections by temporarily disabling the phosphodiesterase-5 enzyme. One of the primary tasks of the PDE5 enzyme is the breakdown of cGMP. Viagra, Cialis, and the other PDE5 inhibitors temporarily deactivate the PDE5 enzyme, which allows the cGMP to open up the blood vessels and promote an erection without any outside interference. The effects of most of the PDE5 inhibitors usually wear off within four or five hours.

Viagra Doesn’t Work for All

While the PDE5 inhibitors have been shown to be safe and effective in most healthy men, roughly one-third of the men who have tried them don’t get the desired results, according to an article posted at NationalGeographic.com. It is always possible that a drug based on the PnTx2-6 peptide might work for them where the PDE5 inhibitors fail to do so. The answer to that question will have to wait for trials of the peptide in humans, which have yet to be conducted.

For those curious to know a bit more about the venomous spider with the erection-friendly bite, here are the basic facts. Also known as the banana spider, the Brazilian wandering spider can be found throughout most of the rain forests of Central and South America. With a leg span of roughly 5 inches, they are imposing creatures. However, they are not that often seen by man, preferring to hunt by night for the insects and other animals that make up their diet.

Spider Bite Case Studies

According to the article at Wired.com, case studies of 422 Brazilians bitten by the wandering spider show that less than 10 percent of those cases were classified as medical emergencies. The most common symptoms in those who were bitten were pain, sweating, an elevated heart rate, and, among the male victims, long-lasting erections.

An erection that lasts four or more hours is no laughing matter and can cause permanent tissue damage. However, the scientists working with the isolated peptide responsible for the erections have genetically modified the compound to harness its erection-supportive properties without causing permanent damage.

Photo credits: Fredrik Tegner, Andreas Kay

Don Amerman is a freelance author who writes extensively about a wide array of nutrition and health-related topics.

Don Amerman has spent more than three decades in the business of writing and editing. During the last 15 years, his focus has been on freelance writing. For almost all of his writing, He has done all of his own research, both online and off, including telephone and face-to-face interviews where possible. Don Amerman on Google+