Effects of acute cannabis use and short-term deprivation on plasma prolactin and dopamine-beta-hydroxylase in long-term users

Cannabis and Cannabinoids: Kinetics and Interactions

Cannabis sativa and related products are widely used, but their potential to cause significant clinical interactions remains unclear, particularly for cannabinoid-enriched or otherwise concentrated products. The pharmacokinetics of most cannabis products is not known. Where information is known, there is wide variation. Extrapolation of limited clinical data is complicated by the complexity and variability of cannabis products as well as their delivery through various routes of administration. In vitro evidence shows that the major cannabinoids are substrates for numerous metabolic enzymes, including the cytochrome P450 metabolizing enzymes. Whereas many consumers consider cannabis products to be safe relative to alternative prescription or narcotic drugs, clinical reports of cannabis-related drug interactions and adverse events are increasing in frequency. Patients using these products, whether for medical or nonmedical purposes, together with conventional therapeutic agents may be at increased risk of adverse events, including therapeutic failure, and require enhanced monitoring.

Does cannabis affect dopaminergic signaling in the human brain? A systematic review of evidence to date

A significant body of epidemiological evidence has linked psychotic symptoms with both acute and chronic use of cannabis. Precisely how these effects of THC are mediated at the neurochemical level is unclear. While abnormalities in multiple pathways may lead to schizophrenia, an abnormality in dopamine neurotransmission is considered to be the final common abnormality. One would thus expect cannabis use to be associated with dopamine signaling alterations. This is the first systematic review of all studies, both observational as well as experimental, examining the acute as well as chronic effect of cannabis or its main psychoactive ingredient, THC, on the dopamine system in man. We aimed to review all studies conducted in man, with any reported neurochemical outcomes related to the dopamine system after cannabis, cannabinoid or endocannabinoid administration or use. We identified 25 studies reporting outcomes on over 568 participants, of which 244 participants belonged to the cannabis/cannabinoid exposure group. In man, there is as yet little direct evidence to suggest that cannabis use affects acute striatal dopamine release or affects chronic dopamine receptor status in healthy human volunteers. However some work has suggested that acute cannabis exposure increases dopamine release in striatal and pre-frontal areas in those genetically predisposed for, or at clinical high risk of psychosis. Furthermore, recent studies are suggesting that chronic cannabis use blunts dopamine synthesis and dopamine release capacity. Further well-designed studies are required to definitively delineate the effects of cannabis use on the dopaminergic system in man.

The effects of cannabinoids on serum cortisol and prolactin in humans

BACKGROUND

Cannabis is one of the most widely used illicit substances, and there is growing interest in the therapeutic applications of cannabinoids. While known to modulate neuroendocrine function, the precise acute and chronic dose-related effects of cannabinoids in humans are not well-known. Furthermore, the existing literature on the neuroendocrine effects of cannabinoids is limited by small sample sizes (n = 6-22), heterogeneous samples with regard to cannabis exposure (lumping users and nonusers), lack of controlling for chronic cannabis exposure, differing methodologies, and limited dose-response data. Delta-9-tetrahydrocannabinol (Delta-9-THC) was hypothesized to produce dose-related increases in plasma cortisol levels and decreases in plasma prolactin levels. Furthermore, relative to controls, frequent users of cannabis were hypothesized to show altered baseline levels of these hormones and blunted Delta-9-THC-induced changes of these hormones.

MATERIALS AND METHODS

Pooled data from a series of laboratory studies with multiple doses of intravenous Delta-9-THC in healthy control subjects (n = 36) and frequent users of cannabis (n = 40) was examined to characterize the acute, chronic, and acute on chronic effects of cannabinoids on plasma cortisol and prolactin levels. Hormone levels were measured before (baseline) and 70 min after administration of each dose of Delta-9-THC. Data were analyzed using linear mixed models with +70 min hormonal levels as the dependant variable and baseline hormonal level as the covariate.

RESULTS

At socially relevant doses, Delta-9-THC raised plasma cortisol levels in a dose-dependent manner but frequent users showed blunted increases relative to healthy controls. Frequent users also had lower baseline plasma prolactin levels relative to healthy controls.

CONCLUSIONS

These group differences may be related to the development of tolerance to the neuroendocrine effects of cannabinoids. Alternatively, these results may reflect inherent differences in neuroendocrine function in frequent users of cannabis and not a consequence of cannabis use.

Cannabis, tobacco, and caffeine use modify the blood pressure reactivity protection of ascorbic acid

Cannabis, caffeine, and tobacco use are associated with increased mesolimbic dopamine activity. Ascorbic acid (AA) modulates some dopaminergic agent effects, and was recently found to decrease systolic blood pressure (SBP) stress reactivity. To examine how AA SBP stress reactivity protection varies by use of these substances, data from an AA trial (Cetebe, 3000 mg/day for 14 days; N=108) were compared by substance use level regarding SBP reactivity to the anticipation and actual experience phases of a standardized psychological stressor (10 min of public speaking and arithmetic). Self-reported never users of cannabis, persons not currently smoking tobacco, and persons consuming three or more caffeine beverages daily all exhibited AA SBP stress reactivity protection to the actual stressor, but not during the anticipation phase. Conversely, self-reported ever cannabis users, current tobacco smokers, and persons consuming less than three caffeine beverages daily exhibited the AA SBP protection during the anticipation phase, but only the lower caffeine consumption group exhibited AA protection during both phases. Covariates (neuroticism, extraversion, and depression scores, age, sex, body mass index) were all nonsignificant. Results are discussed in terms of dopaminergic effects of these substances, modulation of catecholaminergic and endothelial activity, and AA support of coping styles.

Neuroendocrine abnormalities in recreational ecstasy (MDMA) users: is it ecstasy or cannabis?

BACKGROUND

The purpose of this study was to investigate neuroendocrine function in ecstasy (3,4-methylenedioxymethamphetamine = MDMA) users and controls.

METHODS

Prolactin response to d-fenfluramine was assessed in abstinent ecstasy users with concomitant use of cannabis only (n = 24, male/female 13/11) and in two control groups: healthy nonusers (n = 13, female) and exclusive cannabis users (n = 7, male).

RESULTS

Prolactin response to d-fenfluramine was slightly blunted in female ecstasy users. Both male user samples exhibited a weak prolactin response to d-fenfluramine, but this was weaker in the group of cannabis users. Baseline prolactin and prolactin response to d-fenfluramine were associated with the extent of previous cannabis use.

CONCLUSIONS

Endocrinological abnormalities of ecstasy users may be closely related to their coincident cannabis use. Cannabis use may be an important confound in endocrinological studies of ecstasy users and should be looked for more systematically in future studies.

Effects of chronic marijuana use on testosterone, luteinizing hormone, follicle stimulating hormone, prolactin and cortisol in men and women

To investigate possible effects of chronic marijuana use on reproductive and stress hormones, we assayed testosterone, luteinizing hormone, follicle stimulating hormone, prolactin, and cortisol in 93 men and 56 women with a mean (+/- S.E.) age of 23.5 +/- 0.4 years. Hormone values were compared among groups of subjects stratified according to frequency of marijuana use (frequent, moderate and infrequent; N = 27, 18, and 30, respectively) and non-using controls (N = 74). Chronic marijuana use showed no significant effect on hormone concentrations in either men or women.

A 12-step treatment approach for marijuana (Cannabis) dependence

Marijuana (Cannabis) dependence (addiction) is a disorder for which treatment is essential and relatively sophisticated. A basic assumption in the treatment model is that marijuana addiction involves pathological processes in the physical, mental (cognitive), and emotional (mood) states of the addicted individual. These pathological processes constitute a disease entity that is diagnosable, treatable, and has a predictable course. One approach for the treatment of marijuana addiction involves physicians, psychologists, counselors, and social workers who treat the disease of marijuana addiction. We present this approach to treatment of marijuana addiction as representative of a popular method but not as the only modality available.

Effects of acute cannabis use on urinary neurotransmitter metabolites and cyclic nucleotides in man

The noradrenaline, dopamine and serotonin metabolites methoxyhydroxyphenylglycol (MHPG), homovanillic acid (HVA), and 5-hydroxyindoleacetic acid (5-HIAA), as well as the cyclic nucleotides c-AMP and c-GMP were estimated in urine samples of five normal volunteers. Ten control samples and two samples after cannabis use were analyzed for each volunteer. Cannabis use caused significant decreases in MHPG and c-AMP, and increases in HVA, while 5-HIAA and c-GMP excretion remained unchanged. The results indicate that cannabis use interferes with catecholaminergic mechanisms in man, decreasing the noradrenaline and increasing dopamine turnover, probably through action on presynaptic receptors.

Acute effects of natural and synthetic cannabis compounds on prolactin levels in human males

Plasma prolactin levels were determined in 23 adult males prior to and following administration of delta 9-tetrahydrocannabinol (THC) (17.5 mg orally), a synthetic cannabis compound, Nabilone (2 mg orally), a 1-g marihuana cigarette containing 1.83% THC, smoked under controlled conditions and placebo capsules and cigarettes for each of the active cannabis compounds. In order to control for possible influence of previous cannabis use history on prolactin response, three groups of subjects were studied--regular (daily) marihuana users, intermittent (weekly) marihuana users, and occasional (monthly) marihuana users. Each subject served as his own control for each drug condition. Double blind studies were conducted on a residential research ward. All baseline prolactin values were within the normal range for healthy adult males. There were no statistically significant differences in plasma prolactin levels among the three subject groups prior to administration of THC, Nabilone, marihuana or their respective placebos. There were no statistically significant changes in prolactin levels following TCH, Nabilone or marihuana smoking. Only placebo administration to regular and occasional marihuana users was followed by a significant increase in plasma prolactin levels. These findings indicate that acute administration of cannabis compounds, either orally or via smoking, does not significantly affect plasma prolactin levels in adult human males.