The intracellular parasite Toxoplasma gondii (Nicolle et Manceaux, 1908) infects humans resulting in acute toxoplasmosis, an infection that in immunocompetent people is typically mild but results in persistent latent toxoplasmosis. In that T. gondii appears to affect dopamine synthesis and because addicting drugs affect midbrain dopamine transmission, latent toxoplasmosis could influence substance use. Using both the third and continuous National Health and Nutrition Examination Surveys from the US Centers for Disease Control and Prevention, we used logistic regression to test for associations between T. gondii seropositivity and subject self-report of having ever used tobacco, alcohol, marijuana, cocaine, heroin, or methamphetamine. In the third NHANES dataset, which included data for tobacco, alcohol, marijuana and cocaine, T. gondii seropositivity was associated with a reduced likelihood of self-reported marijuana (OR = 0.71 [95% CI: 0.58; 0.87]; p = 0.001) and cocaine use (OR = 0.72 [95% CI: 0.56; 0.91]; p = 0.006). In the continuous National Health and Nutrition Examination Surveys dataset, which included data for all six substances, T. gondii seropositivity was associated with a reduced likelihood of self-reported tobacco (OR = 0.87 [95% CI: 0.76; 1.00]; p = 0.044), marijuana (OR = 0.60 [95% CI: 0.50; 0.72]; p < 0.001), heroin (OR = 0.60 [95% CI: 0.42; 0.85]; p = 0.005) and methamphetamine use (OR = 0.54 [95% CI: 0.38; 0.77]; p = 0.001). We observed interactions between sex and T. gondii seropositivity in the prediction of self-reported use of tobacco and alcohol. Further, T. gondii seropositivity appeared to remove the protective effect of education and economic status against self-reported cigarette smoking. These findings suggest that T. gondii seropositivity may be inversely associated with some but not all types of substance use in US adults., Andrew N. Berrett, Shawn D. Gale, Lance D. Erickson, Evan L. Thacker, Bruce L. Brown, Dawson W. Hedges., and Obsahuje bibliografii
Psychostimulants, as well as cannabinoids, have been shown to
significantly affect a great variety of behaviors in both humans
and laboratory animals. Our previous studies have repeatedly
demonstrated that the application of the vehicle for
psychostimulants, i.e. saline, to control groups, generated
different behavioral test results compared to absolute naïve
controls (i.e. without any injection). Therefore, our present study
has set three goals: (1) to evaluate the effect of three different
psychostimulant drugs, (2) to evaluate the effect of three doses
of delta 9-tetrahydrocannabinol (THC), and (3) to evaluate the
effect of saline and ethanol injections vs sham injections and no
injection on spontaneous behavior of adult male rats. The
LABORAS test (Metris B.V., Netherlands) was used to examine
spontaneous locomotor activity and exploratory behavior in an
unknown environment over 1 h. In Experiment 1,
psychostimulant drugs were tested: single subcutaneous (s.c.)
injections of amphetamine (5 mg/kg), cocaine (5 mg/kg), and
3,4-methylenedioxymethamphetamine (MDMA) (5 mg/kg) were
applied prior to testing. Control animals received the same
volume (1 ml/kg) of s.c. saline. In Experiment 2, the effect of
three doses of THC (1, 2, and 5 mg/kg, s.c.) were examined.
An s.c. injection of vehicle (ethanol) was used as a control. In
Experiment 3, injections of saline and ethanol were compared to
the group receiving a sham s.c. injection and to a group of
absolute “naïve” controls. Our results demonstrated that (1) all
psychostimulants increased locomotion time, distance traveled,
and speed while decreasing immobility time of adult male rats
relative to saline controls. The most prominent effect was
associated with MDMA; (2) The effect of THC was dosedependent and was most apparent within the first 10 min of the
LABORAS test. (3) With regard to the effect of injection: absolute
controls (without injection) compared to animals injected with
ethanol, saline, or sham-injected displayed reduced immobility
time, traveled longer distances, and had increased speed. In
conclusion, our data showed drug dependent behavioral changes
in adult male rats after application of psychostimulants and
cannabinoids. Our findings also suggest that not only drugs but
the actual single injection per se also affects the behavior of
laboratory animals in an unknown environment. This effect
seems to be associated with the acute stress associated
with the injection.