“The recent discovery that the hippocampus is able to generate new neurons throughout a human’s lifespan has changed the way we think about the mechanisms of psychiatric disorders and drug addiction,” says Wen Jian and colleagues in a study published in the Journal of Clinical Investigation in 2005. It appears that cannabinoids are able to modulate pain, nausea, vomiting, epilepsy, ischemic stroke, cerebral trauma, multiple sclerosis, tumors, and many other disorders. Cannabinoids act on two types of receptors, the CB1 receptors (found mainly in the brain) and the CB2 receptors (found mainly in the immune system). The CB1 receptor is one of the most abundant G protein coupled receptors in the mammalian brain and it accounts for most, if not all, of the centrally mediated effects of cannabinoids. Cannabionoid receptors are evolutionarily conserved amoung various vertebrates and invertebrates which have been separate for 500 million years.

Hippocampal neurogenesis is suppressed following chronic administration of the major drugs of abuse (including opiates, alcohol, nicotine, and cocaine). However, CB1-knockout mice display significantly decreased hippocampal neurogenesis, suggesting that CB1 receptors activated by endogenous, plant-derived, or synthetic cannabinoids may promote hippocampal neurogenesis.

Wen Jiang and colleagues have given the first evidence suggesting that both embryonic and adult hippocampal neural stem/progenitor cells (NS/PCs) express CB1 receptors. Cannabinoids can regulate the proliferation of hippocampal NS/PCs by acting on CB1 receptors. They found that both the synthetic cannabinoid HU210 and the endocannabinoid anandamide profoundly promote embryonic hippocampal NS/PC proliferation.

Chronic, but not acute, HU210 significantly increases the number of newborn hippocampal neurons in adult rats by promoting NS/PC proliferation. These promoting effects are not the outcome of hippocampal neuronal death, as no neuronal loss or dying hippocampal neurons were detected following chronic HU210 injection. A significant increase was observed in the hipoppocampal newborn neurons of mice following twice-daily HU210 injection for 10 days.

It has been shown that acute, high doses of cannabinoids produce anxiety-like effects in rats and depression-like effects in mice. But chronic administration of high, but not low, doses of HU210 exerts anxiolytic- and antidepressant-like effects. This suggests that cannabinoids are the only illicit drug that can promote adult hippocampal neurogenesis following chronic administration. “This increase in hippocampal neurogenesis underlies the mechanism of anxiolytic- and andtidepressant-like effects produced by a high dose chronic HU210 treatment.”

Source: Jiang W, Zhang Y, Xiao L, Cleemput JV, Ji S-P, Bai G, & Zhang X (2005). Cannabinoids promote embryonic and adult hippocampus neurogenesis and produce anxiolytic- and antidepressant-like effects. Journal of Clinical Investigation, 115, 3104-3116

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-Bryan Perkins


Here are some ‘funny’ cigarette ads from the Stanford School of Medicine website.  This is the kind of thing that really hurts the public’s trust of science.  Alas, enjoy:

It’s a Fact! Cigarettes embody an ‘energizing effect’, a quick restoration of the natural flow of body energy, and a delightful relief from fatigue and irritability. Not only that, but the ‘wholy natural’ and ‘utterly delightful’ energizing effect of Camel cigarettes has ‘recieved full scientific confirmation’.

‘So whenever you feel run down, tired and irritable, just light a Camel.’

‘You can smoke just as many of these delightful Camels as you want. You can increase your flow of energy over and over again. And you need never worry about your nerves. For remember: Camel’s costlier tobaccos never get on your nerves.’

Clear Evidence

‘Everyone knows that sunshine mellows – that’s why TOASTING includes the use of the Ultra Violet Ray. LUCKY STRIKE – the finest cigarette you ever smoked, made of the finest tobaccos – the Cream of the Crop – THEN“IT’S TOASTED” – Everyone knows that heat purifies and so TOASTING removes harmful irritants that cause throat irritation and coughing. No wonder 20,679 physicians have stated LUCKIES to be less irritating.’

‘Consistent with its policy of laying the facts before the public’, The American Tobacco Company invited one Mr. L. J. Horowitz to review the reports of the people who have witnessed Lucky Strike’s famous Toasting Process. Of course he has no scientific background to add credibility to his claim of ‘Clear Evidence’, but he is the Chairman of the Board for Thompson-Starrett Co., Inc. builders of the new Waldorf-Astoria Hotel, the Paramount Building, the Equitable Building, New York; the General Motors Building in Detroit, and the Palmer House in Chicago. That sure makes me want to trust his scientific opinion in this advertisement that gives his company almost as much publicity as the cigarettes.

Phillip Morris tobaccos are pasteurized for your protection and Thermo-vised for better taste. I guess pressure cooking might help keep the flavor in a cigarette, but I have no idea how pasteurization (or the previous toasting for that matter) would have any effect on how irritating a cigarette is when smoked. You burn the tobacco and breath the smoke either way.

This picture is best left described by the site:

‘Popular faith in medicine was exploited by a series of industry-sponsored “research” and “surveys.” In this era, before the coming of the atomic bomb, little of today’s cynicism concerning the abilities of science to overcome societal problems existed. To exploit this popular sentiment, the industry sponsored “research institutes” & scientific symposia, many of which amounted to little more than propaganda based upon dubious methodology. Health claims were then made on the basis of these supposed studies, as when Chesterfields were advertised (in 1952) with the assertion that “Nose, throat, and accessory organs [were] not adversely affected” after a six-month period of medical observation (including X-rays) by ear, nose, and throat specialists.’

‘A real scientist might be concerned about getting ashes on the microscope slide’

Bottom line, don’t trust advertisements. Something that ‘sounds reasonable’ or looks professional today could be laughed at and mocked for years to come. And, if you liked those science destroying cigarette advertisements you can see more pseudoscience related ads here at the Stanford School of Medicine website, just select view images by theme and you will see Pseudoscience as an option.  Also, you can look here if you want to see a large collection of tobacco ads that are not necessarily Science related. There you can search the ads by country, company, brand, or ad type (just select Camel if you want to see the infamous Joe). And finally, for any more of your tobacco knowledge needs, you can try here at the Tobacco Wiki. They are looking for your help to mine the millions of pages of previously-secret, internal tobacco industry documents now posted on the Internet.

-Bryan Perkins