Long-term cocaine use and its potential effect on bone morphology
Appel, Nicollette Selene
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There is a vast amount of information that the bones can offer and this can be on a macroscopic level, a microscopic level, or both. Understanding the changes in bone morphology can provide an understanding the broader picture of an individual’s life. The natural progression of changes in bone follows the natural progression of life. On the macroscopic level, morphological changes occur to skeletal elements such as the pubic symphysis and the sternal rib ends. These characteristics are used when determining the age of an individual. On the microscopic level, histological methods have been developed to determine the age of an individual based on changes in the microstructure of an element. While age at death estimations are based on a known sequence of change over time, time is not the only variable that effects bone morphology. Different pathologies and trauma can also alter skeletal elements. Just as disease processes and trauma act of signaling pathways in the body that cause changes in bone to occur, drug use also acts on the brain and can affect the same signaling pathways that are involved in bone regulation. It is hypothesized here that chronic cocaine use will have a detectable effect on bone morphology. The study sample used consisted of rats, some exposed to cocaine and others not. The experimental groups consisted of eleven Male Wistar Rats (Rattus norvegicus) from the Laboratory of Behavioral Neuroscience at Boston University in Boston, Massachusetts. The rat’s self-administered cocaine at a 0.3 mg/kg dosage and the concentration of the IV solution was 1.6 mg/ml of cocaine. The control group includes five female Sprague Dawley rats (Rattus norvegicus) from the Boston University Animal Science Center in Boston, Massachusetts. These rats were exposed to a training protocol but were not given any drugs prior. All samples went through a dissection and maceration process to obtain the femora and humeri. Mass, volume, and length measurements were taken for each element to be used for later analysis. One femur was chosen at random from each rodent to be used for histological analysis. Femora were embedded in a 2-part epoxy resin and then cut in half using a diamond band saw. A Buehler IsoMet Low Speed Saw was used to obtain thinner sections and a Buehler MetaServ 250 grinder was used to achieve a thickness of 100-120 μm. India ink was used for staining and all stained sections were put onto slides, covered with Permount and a cover slip, and labeled. Upon microscopic examination, it was determined that the outer circumferential lamellar bone thickness would be measured and compared between the experimental and control groups. Photographs were taken of each cross-section at 1x and 4x magnification through the NIS-element software. The ImageJ image-processing program was used for analysis. The thickness of the outer circumferential lamellar bone and the thickness of the total cross-section was taken at four random locations of each 4x magnification photograph. The ratio of the thicknesses and the outer circumferential lamellar bone thickness alone were compared. When comparing density values calculated from the original mass and volume measurements, a significant difference was found between the control and experimental groups. Samples that had been exposed to cocaine had lower density values than those not exposed to any drugs. The control group mean density equaled 1.492 g/mL and the experimental group mean density equaled 1.082 g/mL. A significant difference was found between the ratio of the thicknesses and between the outer circumferential lamellar bone thickness alone. The experimental group had ratio values significantly higher than the control group. The control groups mean ratio equaled 0.2686 while the experimental groups mean ratio equaled 0.4427. This indicates that in the control group, the outer circumferential lamellar bone thickness, on average, covered about 25% of the total cross-section, and the experimental groups outer circumferential lamellar bone thickness, on average, covered almost 50% of the total cross-section. These results were similar when comparing the outer circumferential lamellar bone thickness alone. The control groups thickness was significantly lower than the experimental groups thickness. The control group’s thickness measurements had a mean of 189.7674 μm and he experimental group’s thickness measurements had a mean of 343.2753 μm. These results are just the preliminary data that shows that chronic cocaine use does have an effect on bone morphology on a microscopic level. Only on histological characteristic was analyzed but there are many more traits that can be analyzed.