Chapter 2

People have been smoking and studying marijuana for hundreds of years. It was first used in ancient India for religious purposes and used for medicine in a variety of ways. It became popular in the United States around the 1960’s although it became illegal in the late 1930’s. There have always been arguments about whether it is good or bad, harmful or helpful, addictive or not, and if it can or can’t be used for medical purposes. The main ingredient in the cannabis plant that people smoke is THC or delta-9 tetrahydrocannabinol. This works on specific parts of the brain’s hardware, called cannabinoid receptors. Activating a cannabinoid receptor with THC creates many cellular reactions that eventually create the high one feels when marijuana is smoked. These receptors naturally exist throughout the brain. They are most common in parts of the brain that influence pleasure, time/sensory perception, memory, thoughts and concentration, which explains the common short term side effects of smoking marijuana such as loosing track of time, a boost of creativity, inability to remember something that just happened, a lowered or heightened concentration (depending on the person), and so on. Smoking marijuana regularly can overwhelm these receptors and cause some negative mental effects. Studies in animals that have been chronically exposed to marijuana experience a cannabinoid withdrawal that leads to an increase in the activation of the stress response system and changes in the activity of nerve cells containing dopamine. Dopamine neurons are involved in the regulation of motivation and reward, and are directly or indirectly affected by all drugs of abuse. From January 1998 to January 2002 several tests were performed on dogs to learn their reactions. The amount of marijuana ingested ranged from ½ grams to 90 grams (a little more that 4 ounces). The dogs developed clinical signs following the oral exposure to marijuana, 99% having neurologic signs and 30% exhibiting...