Autonomic actions of cocaine

Subcellular Effectors of Cocaine Cardiotoxicity: All Roads Lead to Mitochondria-A Systematic Review of the Literature

Cocaine abuse is a serious public health problem as this drug exerts a plethora of functional and histopathological changes that potentially lead to death. Cocaine causes complex multiorgan toxicity, including in the heart where the blockade of the sodium channels causes increased catecholamine levels and alteration in calcium homeostasis, thus inducing an increased oxygen demand. Moreover, there is evidence to suggest that mitochondria alterations play a crucial role in the development of cocaine cardiotoxicity. We performed a systematic review according to the Preferred Reporting Items for Systemic Reviews and Meta-Analysis (PRISMA) scheme to evaluate the mitochondrial mechanisms determining cocaine cardiotoxicity. Among the initial 106 articles from the Pubmed database and the 17 articles identified through citation searching, 14 final relevant studies were extensively reviewed. Thirteen articles included animal models and reported the alteration of specific mitochondria-dependent mechanisms such as reduced energy production, imbalance of membrane potential, increased oxidative stress, and promotion of apoptosis. However, only one study evaluated human cocaine overdose samples and observed the role of cocaine in oxidative stress and the induction of apoptosis though mitochondria. Understanding the complex processes mediated by mitochondria through forensic analysis and experimental models is crucial for identifying potential therapeutic targets to mitigate or reverse cocaine cardiotoxicity in humans.

Acetylcholine signaling genes are required for cocaine-stimulated egg laying in Caenorhabditis elegans

The toxicity and addictive liability associated with cocaine abuse are well-known. However, its mode of action is not completely understood, and effective pharmacotherapeutic interventions remain elusive. The cholinergic effects of cocaine on acetylcholine receptors, synthetic enzymes, and degradative enzymes have been the focus of relatively little empirical investigation. Due to its genetic tractability and anatomical simplicity, the egg laying circuit of the hermaphroditic nematode, Caenorhabditis elegans, is a powerful model system to precisely examine the genetic and molecular targets of cocaine in vivo. Here, we report a novel cocaine-induced behavioral phenotype in C. elegans, cocaine-stimulated egg laying. In addition, we present the results of an in vivo candidate suppression screen of synthetic enzymes, receptors, degradative enzymes, and downstream components of the intracellular signaling cascades of the main neurotransmitter systems that control C. elegans egg laying. Our results show that cocaine-stimulated egg laying is dependent on acetylcholine synthesis and synaptic release, functional nicotinic acetylcholine receptors, and the C. elegans acetylcholinesterases.

Management of the Cardiovascular Complications of Substance Use Disorders During Pregnancy

PURPOSE OF REVIEW

Substance use disorder in pregnancy and subsequent cardiovascular complications are on the rise in the USA. The care of pregnant women with substance use disorder is complex, and requires a thorough understanding of mechanisms of action, pathophysiology, and cardiovascular response during pregnancy. The goal of this review is to provide information about the most common drugs of abuse in pregnancy and to recommend management guidelines.

RECENT FINDINGS

Pregnant women with substance use disorder are at increased risk of significant cardiovascular complications, both as a direct effect of acute intoxication as well as the secondary risk from infection and cardiotoxicity associated with chronic use. This risk must be considered in the antepartum management, delivery, and postpartum periods. Understanding the increased cardiovascular risk of pregnant women with substance use disorder, as well as specific drug interactions, anesthesia considerations, best practices, and management considerations, is important for all clinicians caring for this population.

Antepartum Drug Dependence and Pregnancy- or Birth-related Complications: A Cross-sectional Study of 19 Million Inpatients

Objective

To evaluate the demographic characteristics, hospitalization outcomes [severity, length of stay (LOS), and total expense], and comorbidities in pregnant patients with antepartum drug dependence (ADD).

Methods

We used the national inpatient sample (NIS) and included 19,170,561 female patients (age: 12-40 years) hospitalized for pregnancy- or birth-related complications and grouped by co-diagnosis of ADD. We used descriptive statistics and Pearson’s chi-square test for categorical data and independent sample T-test for the continuous data to measure the differences in demographic and hospital outcomes. A logistic regression model was used to evaluate the odds ratio (OR) for medical and psychiatric comorbidities.

Results

The hospitalizations with ADD declined initially, from 2010 to 2011, followed by an increase of 50% from 2011 to 2014. White pregnant females (77.5%), and those from low-income families (<25^th percentile, 37.1 %) had comorbid ADD. Among medical comorbidities, iron-deficiency anemia was the most prevalent condition in pregnant inpatients (12.0% in ADD vs. 9.2% in non-ADD) followed by obesity and hypertension. Depression (12.9%) was the most prevalent psychiatric comorbidity in ADD inpatients followed by comorbid psychosis (three-fold higher odds). Among patients with substance use disorder (SUD), opioid abuse was the most prevalent one (67.3%) followed by cannabis (11.2%), cocaine (5.7%), amphetamine (4.0%), and alcohol (2.4%). Half of the pregnant inpatients with ADD had moderate severity of illness due to pregnancy or birth-related complications with four-fold higher odds [95% confidence interval (CI): 3.67-8.88]. They also had a higher LOS with a mean difference of 0.88 days (95% CI: 0.904-0.865) and had incurred higher total charges, by USD 3,797 (95% CI: 3,927-3,666), per inpatient admission for pregnancy- or birth-related complications compared to non-ADD inpatients

Conclusion

ADD is associated with the worsening of severity of illness in pregnancy- or birth-related complications and requires acute inpatient care that leads to increased healthcare-related economic burden. The integration of SUD services with primary or maternal care is required to improve outcomes in at-risk women in the reproductive age group.

Stimulant Use in Pregnancy: An Under-recognized Epidemic Among Pregnant Women

Stimulant use, including cocaine, methamphetamines, ecstasy, and prescription stimulants, in pregnancy is increasingly common. In the United States, stimulants are the second most widely used and abused substances during pregnancy and pregnant women using stimulants in pregnancy are at increased risk of adverse perinatal, neonatal, and childhood outcomes. In this review, we describe the pharmacology, pathophysiology, and epidemiology of stimulants, summarize the maternal and neonatal effects of perinatal stimulant use, and outline treatment options for stimulant use disorders among pregnant women. Development of effective treatment strategies for stimulant use disorders identified among pregnant women are urgently needed.

Cocaine-induced reinstatement in rats: evidence for a critical role of cocaine stimulus properties

RATIONALE

The exact behavioral nature of drug-induced reinstatement of drug seeking is still debated. As an incentive, the drug can have general facilitatory influences on appetitive behaviors. As an interoceptive stimulus, the drug can acquire discriminative properties and control behavior.

OBJECTIVE

This study assessed the relative contribution of the incentive versus discriminative properties of cocaine in food-seeking reinstatement.

METHODS

In Experiment 1, eight groups of rats were trained to press a lever for food pellets and experienced cocaine (0, 5, 10, or 15 mg/kg; i.p.), either during the operant conditioning sessions or 4 h after, in another environment without food access. In Experiment 2, to dissociate the role of the operant response per se from the consummatory response, two groups of rats experienced food consumption under cocaine (10 mg/kg; i.p.) either during operant conditioning sessions or during alternate sessions of free access to the food. Then, for both experiments, food pellets were withheld and cocaine injections ceased (extinction). The reinstating effects of noncontingent cocaine (10 mg/kg; i.p.) and food pellet delivery were assessed. Locomotor activity was recorded to probe expression of behavioral sensitization.

RESULTS

Cocaine reinstated lever pressing only in rats having previously performed the operant responses under cocaine. In contrast, food pellet delivery reinstated lever pressing independently of rats' history with cocaine. Locomotor sensitization was evidenced for all cocaine-pre-exposed rats, dissociating sensitization from reinstatement.

CONCLUSIONS

When present during operant conditioning, the stimulus "cocaine" acquires conditioned properties which can then promote reinstatement of the extinguished behavior.

Assessment of the contributions of Na+ channel inhibition and general peripheral action in cocaine-induced conditioned taste aversion

While the rewarding properties of cocaine appear to be mediated by its blockade of central monoamine uptake, the mechanisms and sites of action for cocaine's aversive effects have yet to be determined. Using the conditioned taste aversion (CTA) preparation, the present study examined the role of Na(+) channel blockade in cocaine's aversive effects by comparing cocaine to the local anesthetic procaine at three doses (18, 32 and 50 mg/kg). Furthermore, the role of cocaine's peripheral actions in its aversive effects was examined by comparing cocaine to the quaternary analog cocaine methiodide (equimolar to the three doses of cocaine) in establishing CTAs. Procaine and cocaine methiodide each dose-dependently suppressed saccharin consumption, indicating that the aversive effects of cocaine are, in part, mediated by its inhibition of Na(+) channels and via its activity in the PNS. However, the fact that the aversions induced by procaine and cocaine methiodide were weaker than those induced by cocaine at each dose tested suggests other factors are involved in its aversive effects. Possible reasons for the weaker aversions induced by procaine and cocaine methiodide relative to cocaine were discussed.

Anesthetic implications of drug abuse in pregnancy

Substance abuse has crossed social, economic, and geographic borders and--throughout the world--remains one of the major problems facing society today. The prevalence of substance abuse in young adults (including women) has increased markedly over the past 20 years. Nearly 90% of drug-abusing women are of childbearing age. Consequently, it is not unusual to encounter pregnant women who abuse illicit drugs, as numerous case reports of drug abuse in pregnancy confirm. The diverse clinical manifestations of drug abuse combined with physiologic changes of pregnancy, and pathophysiology of coexisting pregnancy-related disease may lead to life-threatening complications and significantly impact the practice of obstetrical anesthesia. Regardless of the drug(s) ingested and clinical manifestations, it is always difficult to predict the exact anesthetic implications in chemically dependent patients.

The cocaine abusing parturient: a review of anesthetic considerations

PURPOSE

The prevalence of recreational drug abuse among young women, including in pregnancy, has increased markedly over the past two decades. Cocaine remains the drug commonly used for recreational purposes in pregnancy. However, there appears to be an absence of uniform guidelines for obstetric and anesthetic management of pregnant patients with a history of cocaine abuse.

SOURCE

A Medline search for articles highlighting drug abuse in pregnancy, with particular emphasis on cocaine abuse in pregnancy, the drug's impact on the fetus and implications for administration of obstetrical anesthesia was performed.

MAIN FINDINGS

Because the pharmacological actions of cocaine are complex, the clinical picture can be very unpredictable, the diagnosis often difficult, and management at times controversial. The diverse clinical symptomatology of cocaine intake combined with physiologic changes of pregnancy, and pathophysiology of co-existing pregnancy specific disease may lead to life-threatening complications and significantly impact the management of obstetrical anesthesia.

CONCLUSIONS

In the absence of uniform anesthetic guidelines for pregnant patients with a history of cocaine abuse the decision regarding the administration of peripartum analgesia or anesthesia should be individualized and conducted on a case-by-case basis. This article will attempt to heighten the awareness of cocaine use and abuse in pregnancy and review the perioperative anesthetic management of these high-risk parturients.

Labor analgesia for the drug abusing parturient: is there cause for concern?

Drug abuse has crossed geographic, economic and social borders, and it remains one of the major problems facing our society today. The prevalence of recreational drug abuse among young adults (including women) has increased markedly over the past two decades. Nearly 90% of drug abusing women are of childbearing age. Consequently, it is not surprising to find pregnant women with a history of drug addiction. Obstetricians and obstetric anesthesiologists become involved in the care of drug abusing patients either in emergency situations, such as placental abruption, uterine rupture or fetal distress, or in more controlled situations, such as request for labor analgesia. The diverse clinical manifestations of maternal substance abuse may result in life-threatening complications and significantly impact the peripartum care of these patients.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader will be able to list the most commonly abused substances during pregnancy, to describe the various effects of particular substances on pregnancy including the mechanism of desired effect for various substances, and to outline the obstetric anesthesia recommendations for the various substances abused during pregnancy.

Consequences of maternal cocaine on cerebral microvascular functions in piglets

Maternal cocaine abuse is associated with fetal and neonatal neurological abnormalities. Prolonged exposure to cocaine can induce blood flow disorders, growth restriction, and hypoxia in the newborn. We investigated the impact of chronic fetal cocaine exposure on cerebral microvascular reactivity and autonomic function in the piglets. Pregnant pigs received cocaine (1 mg/kg i.v.; twice weekly) or saline throughout the last trimester. Prenatal exposure to cocaine did not have any significant effect on the birth weight of the piglets as compared to the control. Following delivery, effects of recurrent prenatal cocaine exposure on cerebral microvascular functions were examined in piglets (3-6 days old). Pial arteriolar responses to applications of 5-hydroxytryptamine (5-HT), endothelin-1 (ET-1), and clonidine were examined using closed cranial windows. Functional effects of prenatal cocaine exposure on changes in mean arterial pressure (MAP) and pial arteriolar diameter induced by intracisternal injection (i.c.) of clonidine (1 microg/kg) were also determined. Topical applications of 5-HT, ET-1, and clonidine dose-dependently decreased pial arteriolar diameter in the control and these constrictions were significantly enhanced in the in utero cocaine-exposed piglets. Prenatal cocaine exposure did not have any significant effects on the resting MAP and heart rate as there were no differences between the groups. IC clonidine caused sustained decrease in MAP in both groups but the decrease was more pronounced in the cocaine than the control group. IC clonidine causes cerebral microvascular dilation coincident with the development of hypotension. Such dilation was severely attenuated in the cocaine group, even though the hypotension was much more pronounced than in the control. In conclusion, prenatal cocaine exposure resulted in attenuated autoregulatory vasodilation and potentiated responses to vasoconstrictor agents. The mechanisms behind the effects of in utero cocaine exposure on alteration of newborn cerebral functions need further investigation. Such actions may be important in development of cerebral pathologies associated with recurrent prenatal cocaine exposure.

Cocaine abuse in pregnancy – anesthetic implications

Substance abuse, including that of cocaine, has crossed social, economic and geographic borders and remains one of the major problems facing society today. The prevalence of cocaine abuse in young adults (including women) has increased markedly over the past two decades. Nearly 90% of cocaine-abusing women are of childbearing age. Consequently it is not surprising to find pregnant women who abuse this drug, and numerous case reports of cocaine abuse in pregnancy have been published. The diverse clinical manifestations of cocaine abuse combined with physiologic changes of pregnancy, and pathophysiology of coexisting pregnancy-related disease might lead to life-threatening complications and significantly impact the practice of obstetric anesthesia. A complete understanding of the physiology of pregnancy, pathophysiology of pregnancy-specific disorders and anesthetic implications of cocaine abuse in pregnancy is essential to tailor a safe anesthetic plan for this high-risk group of patients.

Combined cardiac effects of cocaine and the anabolic steroid, nandrolone, in the rat

Despite reports of an increase in the incidence of simultaneous cocaine and anabolic steroid abuse, potential adverse interactions between these two drugs on the cardiovascular system are largely unquantified. Cocaine has been reported to induce coronary vasoconstriction, cardiac arrhythmias and conduction delays. Anabolic steroids have been associated with cardiac hypertrophy and hypertension. Utilising both in vivo (radiotelemetry) and in vitro (isolated Langendorff-perfused heart) techniques, our aim was to determine whether anabolic steroids cause cardiac hypertrophy and alter cardiac function, and consequently alter the response of the heart to cocaine. It was found that 15 days of treatment of rats with nandrolone decanoate (20 mg/kg, s.c.) was not sufficient to cause hypertrophy, alter cardiac function or the spread of electrical activity through the heart. However, nandrolone pretreatment was found to significantly potentiate the heart rate response to cocaine (45 mg/kg, i.p.) in vivo. This study indicates that nandrolone significantly elevates the heart rate response to high dose cocaine without changing heart morphology. The mechanism of this interaction remains uncertain.

Autonomic mechanisms in the acute cardiovascular effects of cocaine in conscious rats

We studied the differential involvement of central dopaminergic activation and autonomic nervous system regulatory mechanisms in the cardiovascular responses to cocaine in conscious rats. Sprague-Dawley rats, Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) were instrumented with catheters in the jugular vein and abdominal aorta at least 5 days before the experiment. Intravenous administration of cocaine (0.1-3.0 mg/kg) caused a dose-dependent increase in blood pressure that was biphasic, with a large and rapid increase peaking at 10 s, followed by a mild sustained pressor response. Pressor responses to cocaine were significantly greater in SHR when compared to WKY rats. However, pretreatment with dopamine D1 receptor antagonist SCH 23390 or the D2 receptor antagonist raclopride did not influence the effects of cocaine. Pretreatment with the alpha-adrenoceptor antagonist phentolamine or the ganglion blocker pentolinium blocked the peak response and reversed the more sustained response into a depressor effect. While pretreatment with propranolol alone did not alter the responses to cocaine, in rats pretreated with phentolamine and propranolol neither a pressor response nor a depressor response was observed. In conclusion, cocaine administration caused marked, but short lasting pressor responses that were mediated by sympathetic activation and alpha-adrenoceptor vasoconstriction with little involvement of central dopaminergic mechanisms. The rapid return of blood pressure towards baseline may be mediated by sympathoinhibition and beta-adrenoceptor-mediated vasodilatation, the latter of which being particularly prominent when alpha-adrenoceptor activation was prevented.

Neurobiology of cocaine-induced organic brain impairment: contributions from functional neuroimaging

The present review is directed at imparting the current knowledge regarding functional neuroimaging as a tool for enhancing the understanding of cerebrophysiologic and neurobehavioral consequences of stimulant abuse. Stimulants like cocaine are capable of inducing clinically significant neurocognitive impairment through direct action on the brain, and indirectly through other organs that influence cerebral physiology. Neurochemical dysregulation including profound effects on the serotonergic and dopaminergic systems have substantial physiological and neurobehavioral consequences. Brain hemorrhages, transient ischemic attacks, strokes,and seizures frequently follow cocaine use. The residual cerebropathologic consequences of cocaine are seen only in significant or pronounced brain events when structural neuroimaging techniques such as computed tomography (CT) and magnetic resonance imaging (MRI) are employed. However, recent research with newer functional neuroimaging techniques such as single photon emission, positron emission tomography, and quantitative electroencephalography have revealed high rates of significant alteration in brain function among cocaine users, with negative structural imaging studies. These findings are often associated with impairment on neuropsychological evaluation, also in the absence of positive findings on CT and MRI. Both cerebral metabolic and hypoperfusion anomalies are seen, especially in anterior and temporal brain regions. Observed changes can persist for months, and for some patients, may represent a permanent change in brain functioning.

Reduction in the bioelectric properties of swine tracheal submucosal gland cells in culture after daily short-term exposure to cocaine

Chronic use of cocaine has been associated with respiratory complications. In this study, we investigated the effects of daily short-term cocaine exposure on epithelial bioelectric properties and chloride secretion in response to secretagogues in primary culture of swine tracheal submucosal gland cells grown on microporous inserts. Cell cultures exposed continuously to cocaine for 24 h or intermittently for 30 min daily for up to 3 consecutive days, resulted in a concentration-dependent reduction in transwell voltage and transepithelial resistance. Cocaine (300 microM) treatment for 24 h decreased the voltage and resistance by 87 and 75%, respectively. The voltage and resistance were also substantially decreased after 3 days of intermittent cocaine (10-30 microM) exposure. Cocaine exposure protocols used here did not enhance lactate dehydrogenase (LDH) release. Chloride secretion was measured as short-circuit current utilizing Ussing chamber methodology. Cocaine exposure did not change the decreases in short-circuit current caused by amiloride (10 microM), but reduced the increases in short-circuit current induced by acetylcholine and isoproterenol. After 3 days of intermittent cocaine (30 microM) exposure, the maximal acetylcholine and isoproterenol responses were reduced by 67 and 71%, respectively. Therefore, cocaine exposure continuously for 24 h or intermittently for 30 min daily for up to 3 days decreased basal transepithelial voltage as well as resistance and reduced the responses to cholinergic and beta-adrenoceptor agonists. These results suggest that alterations in epithelial function can occur even after daily transient cocaine exposure.

The depletion of monoamines blocks the sympathoinhibitory response to cocaine

Recent studies have shown that cocaine decreases, rather than increases sympathetic nerve discharge (SND). Whether these sympathoinhibitory responses are the result of cocaine's actions on monoaminergic transmission (i.e. blockade of neuronal uptake or stimulation of transmitter release) or its local anesthetic actions is not known. The purpose of the present study was to determine the degree to which cocaine's actions on monoaminergic transmission are involved in mediating the sympathoinhibitory response to this drug. We examined the mean arterial pressure, heart rate and splanchnic sympathetic nerve responses elicited by cocaine (1 mg/kg, i.v.) in pentobarbital-anesthetized rats depleted of monoamines. Monoamines were depleted by administering reserpine (10 mg/kg, i.p.) either 24, or 48 and 24 h before the experiment. The rats were also given alpha-methyl-p-tyrosine (200 mg/kg, i.p.) 2 h before the experiment. Vehicle-treated rats served as controls. Depletion of monoamines markedly reduced resting arterial pressure and heart rate and significantly attenuated the pressor response and tachycardia elicited by tyramine (1 mg/kg, i.v.). In control rats, cocaine elicited marked (-64 +/- 4%) and prolonged (44 +/- 4 min) decreases in SND. The magnitude (-34 +/- 11%) and duration (23 +/- 6 min) of these responses were significantly attenuated after 1 day of monoamine depletion. After 2 days of depletion, the sympathoinhibitory response was abolished and was replaced by a small, brief increase in SND (10 +/- 3%). The pressor responses were similar in control and depleted rats, while the bradycardic response (-33 +/- 4 bpm) was significantly reduced after 1 and 2 days of monoamine depletion to -20 +/- 3 and -15 +/- 2 bpm, respectively. We conclude that a functionally intact monoaminergic system is essential for the sympathoinhibitory response to cocaine. Whether the pressor responses result from a non-monoaminergic or a reserpine and/or alpha-methyl-p-tyrosine resistant catecholaminergic mechanism is unknown.

Cocaine and exercise: temporal changes in plasma levels of catecholamines, lactate, glucose, and cocaine

To determine the combined sympathoadrenal effects of cocaine and exercise in awake animals, rats were assigned to one of four treatment groups: saline-rest (SR), saline-exercise (SE), cocaine-rest (CR), and cocaine-exercise (CE). Venous blood samples from jugular catheters were obtained at -40, 0-4, 7, 10, 13, 16, 19, 26, and 36 min after intravenous injection of cocaine (5 mg/kg) or saline and the simultaneous onset of a 16-min treadmill run (26 m/min, 10% grade). CE increased plasma epinephrine (24.2 nM at 16 min), norepinephrine (28.0 nM at 10 min), and lactate (11.2 mM at 4 min) to levels 2-5 times greater than either treatment (SE and CR) alone (P<0.05) and 11-35 times higher that SR. Blood glucose values were significantly depressed in CE (-33% vs. SE) but increased in CR (+26% vs. SR). Plasma cocaine peaked < 2 min after injection in both CR and CE, and the peak was 69% higher in CE (P<0.05); however, the plasma elimination half-life (12-14 min) was not different. These results indicate that the combined effect of the two sympathoadrenal stimulants, exercise and cocaine, amplify the catecholamine responses to levels far greater than when each stimulant is used alone.

Sympathetic nerve responses elicited by cocaine in anesthetized and conscious rats

Recent evidence suggests that cocaine decreases rather than increases sympathetic nerve discharge (SND). The purpose of the present study was to provide the first complete characterization of the dose-response relationships of cocaine (0.005-3 mg/kg, IV) for arterial pressure, heart rate, and lumbar, splanchnic, or renal SND in pentobarbital-anesthetized rats. Cocaine was also tested in conscious rats. In pentobarbital-anesthetized rats cocaine elicited prolonged (lasting up to 56 min), dose-dependent decreases in SND on all three nerves. The splanchnic nerve was significantly more sensitive to the inhibitory actions of cocaine than was the lumbar nerve. Cocaine increased arterial pressure and elicited bradycardia at doses above 0.5 mg/kg. Comparison of the dose-response curves of cocaine for splanchnic SND in sham-operated and sinoaortically deafferentated (SAD) rats showed that the baroreceptor reflex made only a minor contribution to the magnitude of sympathoinhibitory response. However, the duration of the sympathoinhibitory response was significantly shorter in SAD than in sham animals. In conscious rats, cocaine (0.1 and 1.0 mg/kg) elicited a pattern of neural and cardiovascular responses similar to that seen in anesthetized rats, except that the prolonged sympathoinhibitory responses were preceded by a brief (lasting < 10 s) increase in SND. From these data we conclude that cocaine produces prolonged decreases in SND in conscious and anesthetized rats. These sympathoinhibitory responses do not appear to result from baroreceptor reflex activation and may involve a central mechanism of action.

Proadrenomedullin NH(2)-terminal 20 peptide, a new product of the adrenomedullin gene, inhibits norepinephrine overflow from nerve endings

Proadrenomedullin NH(2)-terminal 20 peptide (PAMP) and adrenomedullin, which are derived from proadrenomedullin, exhibit remarkable hypotensive action. We investigated the effect of PAMP and adrenomedullin on peripheral sympathetic neutral transmission. Using perfused rat mesenteric arteries, PAMP (0, 1, 5, and 10 pmol/ml) decreased norepinephrine overflow by periarterial electrical nerve stimulation in a dose-dependent fashion (0.244 +/- 0.043, 0.231 +/- 0.048, 0.195 +/- 0.061 and 0.168 +/- 0.051 ng/gram tissue weigh: NS, P < 0.05, and P < 0.02, respectively). In contrast to PAMP, adrenomedullin (1, 5, and 10 pmol/ml) did not change it. In contrast, vasoconstrictive response of mesenteric arteries to exogenous norepinephrine was significantly attenuated by 10 pmol/ml of adrenomedullin but not by the same dose of PAMP. Calcitonin gene-related peptide (8-37) [CGRP(8-37)], a CGRP receptor antagonist, inhibited the vasodilatory effect of adrenomedullin but could not suppress the sympathoinhibitory effect of PAMP. Neither a nicotinic antagonist, hexamethonium, nor a presynaptic alfa2 antagonist, yohimbine, blocked the sympathoinhibitory effect of PAMP. Thus, it suggests that PAMP and adrenomedullin, which are derived from the same gene, exhibit different hypotensive mechanisms: PAMP inhibits neural transmission at peripheral sympathetic nerve ending, although adrenomedullin directly dilates vascular smooth muscle, possibly through CGRP-like receptor.

Catecholaminergic responses in vas deferens isolated from rats submitted to acute swimming stress

The study was performed to examine the responses to catecholamines in vas deferens isolated from rats submitted to acute swimming-induced stress. It was demonstrated that acute stress induces a significant subsensitivity of rat vas deferens to norepinephrine. This subsensitivity was inhibited when the experiment was carried out in the presence of either cocaine (10-5 M) or timolol (10-5 M). On the other hand, the rat vas deferens sensitivity to methoxamine was significantly increased by acute swimming-induced stress. Thus, despite acute swimming stress inducing a reduction in response to norepinephrine, the alpha1-adrenoceptor-mediated contractile response was increased. Additionally there were increases in neuronal uptake and beta2-adrenoceptor activity that opposes the alpha1-adrenoceptor activity. Integrated, these phenomena are responsible for the rat vas deferens subsensitivity to norepinephrine which may be involved in body homeostasis in stressogenic situations.

Cocaine-induced cerebrovascular impairment: challenges to neuropsychological assessment

The patient who presents for evaluation and/or subsequent treatment of a neurological or psychiatric complaint accompanied by a positive history of substance abuse has generally received only modest attention in the clinical practice literature. Significantly more clinical attention has focused on the neurobehavioral sequelae of more pronounced brain insults, despite the rapid emergence of literature detailing psychopharmacologic-induced changes in brain-behavior functioning. This article describes recent clinical research findings related to the neuropsychology of cocaine use and associated issues of neurobiology and psychopharmacology. A description of strategies that have proven effective for assessing this population will be discussed. An emphasis on neurocognitive impairment that may precede as well as occur consequent to cocaine use are also examined. The literature reviewed here generally supports the conclusion that subgroups of cocaine abusing patients may demonstrate sustained brain perfusion anomalies and persistent neurocognitive deficits.

Cocaine LD50 in Long-Evans rats is not altered by pregnancy or progesterone

Progesterone increases cocaine's cardiovascular toxicity in sheep and rats. To determine whether progesterone enhances the lethality of cocaine, nonpregnant female rats were treated with either IM progesterone (P4) or vehicle, and pregnant rats (Preg) were untreated. The rats received one IP injection of cocaine at a dose between 25-75 mg/kg and were observed for seizures and/or death. All 62 rats that died did so within 17 min, preceded by seizures in 90.3%. Mean times-to-seizure and times-to-death, and mean lethal serum cocaine concentrations did not differ among groups. Serum progesterone levels (ng/ml +/- SEM) at the time of death were different among groups: 24 +/- 1.7 (C), 102 +/- 6.4 (P4), and 139 +/- 5.2 (Preg). Logistic regression dose/fatality curves, LD50s, and LD10s for the pregnant, progesterone, and control groups were not significantly different from one another. Though progesterone has enhanced cocaine's cardiac toxicity in some studies, it does not increase the risk of death from acute cocaine exposure in rats.

PET studies of cocaine inhibition of myocardial norepinephrine uptake

Positron emission tomography (PET), [11C]cocaine, and (-)-6-[18F]fluoronorepinephrine [(-)-6-[18F]NE] were used to determine the extent to which the binding of labeled cocaine in the baboon heart represents binding to the norepinephrine transporter and to characterize the functional consequences of cocaine administration on the norepinephrine transporter. Peak heart binding of [11C]cocaine was high (0.038-0.055%/g) and clearance was rapid (t1/2 from peak: 2.5-9 min) for both tracer doses and a pharmacological dose. The binding of a tracer dose of labeled cocaine could not be inhibited by desipramine, tomoxetine, cocaine, nomifensine, or benztropine. The behavior of a pharmacological dose of [11C]cocaine could not be distinguished from a tracer dose and also could not be inhibited by tomoxetine. However, pretreatment with cocaine profoundly inhibited norepinephrine uptake as assessed by (-)-6-[18F]NE. Recovery was slow with only 48% of the baseline (-)-6-[18F]NE uptake being recovered by 78 minutes after cocaine administration. [11C]Benzoylecgonine, a vasoactive metabolite of cocaine, showed negligible retention in heart. The results of this study (i.e., the rapid clearance of cocaine from the heart, the inability to inhibit cocaine binding with desipramine and tomoxetine, and its relatively long-lasting effects on norepinephrine uptake) reinforce the need to understand the link between cocaine pharmacokinetics and norepinephrine transporter function and its relationship to cardiotoxicity.

Quantitative autoradiographic measurement of cocaine-induced regional myocardial metabolic changes in hypertensive rats

A rat model of hypertensive cardiomyopathy was studied to evaluate the acute effects of cocaine on the myocardium. Using autoradiographic microimaging techniques, myocardial perfusion (201Tl) and energy substrate utilization (glucose: [14C]2-fluoro-2-deoxy-D-glucose-[14C]2DG and fatty acid (15-[p-iodophenyl])-3-R,S-methyl pentadecanoic acid-[131I]BMIPP) were studied in Dahl strain salt-sensitive normotensive and hypertensive rats with and without intravenous cocaine. The right ventricle, septum, endocardium and epicardium of the left ventricle were analyzed. Increased perfusion (18%) was seen in the myocardium of the hypertensive rats as compared to the normotensive rats. There was higher [14C]2DG (254%) and lower fatty acid (13.2%) uptake in the hypertensive rats, indicative of a shift from aerobic to anaerobic substrate utilization. In cocaine-treated normotensive rats, a generalized decrease in myocardial perfusion (30%) and increased glucose metabolism (89%) was seen. In cocaine-treated hypertensive rats, the increased myocardial perfusion (16%) was heterogeneous and was more pronounced in septum and epicardium. The endocardium and epicardium in the hypertensive rats showed an overall increase (23%) in glucose utilization after cocaine which was not as dramatic as was seen in the normotensive heart and a slight increase in fatty acid utilization. These results are consistent with prior observations that under pressure overload the myocardium responds non-uniformly. It may well be that the hypertensive cardiomyopathic heart is unable to respond to the challenge of cocaine by further increasing glucose utilization. These data obtained in an animal model of hypertension seem to indicate that hypertension may increase the risk of cardiac complications related to cocaine.

Cocaine-induced rausch: overt behaviour and plasma concentrations in rhesus monkeys

This study was designed to characterize the cocaine-induced rausch or hyperarousal syndrome in rhesus monkeys. This syndrome mimics the stage observed in human abusers bingeing on cocaine and is considered crucial in the progression from recreational use to compulsive abuse. However, little research has focused on this important aspect of cocaine use. Cocaine was administered i.v. at doses of 0.0, 0.5, 1.0 and 2.0 mg/kg. Plasma concentrations were determined by gas chromatograph mass spectrometry (GC/MS) using deuterated internal standards d3 cocaine and d3 benzoylecgonine (BE). Mean plasma concentrations of cocaine, were on samples collected 1 min after infusion, 46 +/- 31, 88 +/- 15 and 275 +/- 116 mg/microliters in the 0.5, 1.0 and 2.0 mg/kg dose groups, respectively. There were no detectable concentrations of BE in any of the specimens nor was cocaine detected in the saline controls. Analysis of the behavioural data revealed that the 0.5 and 1.0 mg/kg results were intermediate between the results obtained at doses of 0.0 and 2.0 mg/kg and that the 1.0 mg/kg dose produced a higher response than the 0.5 mg/kg dose up to the 12 min. Regarding individual behavioural signs, those designated escape attempts, checking, feinting, restlessness, searching, vocalizing, chewing, crouching and wide-eyed were noted most frequently. The results showed dose-response relationships for both plasma concentrations of cocaine and for the total number of overt behavioural signs. The plasma concentrations were in the range reported for human cocaine abusers.

Respiratory patterning following cerebral ventricular administration of cocaine

Intravenous (IV) cocaine in the conscious cat causes extreme tachypnea and reduction in breath-to-breath variability. In this study, we examined respiratory patterning following administration of cocaine into the cerebral ventricles. Intraventricular cocaine elicited a tachypnea that was nearly identical to that for IV cocaine. At the high dose, peak respiratory rate increased by 380%. Breath-to-breath variability was dramatically reduced by cocaine, especially in the early stages of the intoxication; during these stages, the tachypnea was occasionally interrupted by prolonged inspiratory efforts. Procaine was administered as a control for the anesthetic effects of cocaine and caused an initial tachypnea that was similar to that for cocaine. For both cocaine and procaine, the mean ratios of inspiratory to expiratory durations were unaffected, indicating that the tachypnea was accomplished by approximately equal reductions in inspiratory and expiratory durations. We conclude that the tachypnea following cocaine administration results principally from central rather than peripheral mechanisms. In addition, the data suggest that anesthetic actions mediate the principal respiratory effects of cocaine.

Cocaine abuse in North America: a milestone in history

The euphoric effects of coca leaves have been known to mankind for thousands of years. Yet the first epidemic of cocaine use in America occurred during the late 19th century. Initially, there were no laws restricting the consumption or sale of cocaine. In fact, cocaine was freely available in drug stores, saloons, from mail-order vendors, and even in grocery stores. It is reported that one drug manufacturer, in 1885, was selling cocaine in 15 different forms, including cigarettes, cheroots, inhalants, cordials, crystals, and solutions. Many famous imported wines, such as "Vin Mariani," contained a mixture of wine and coca. For consumers on budgets, the wonder drug was available as Coca-Cola and dozens of other soda pops and pick-me-up drinks. One of them even had a simple and direct name, Dope. Soon enough, the ill effects of cocaine became apparent, and by the 1920s cocaine was the most feared of all illicit drugs. Most states began enacting laws against cocaine use. President William Taft proclaimed cocaine as Public Enemy No. 1, and in 1914 the Congress passed the Harrison act, which tightly regulated the distribution and sale of cocaine. By the late 1950s, cocaine use in the United States was simply considered a problem in the past. Unfortunately, the people who were aware of the nation's first cocaine epidemic gradually passed away, and America once again was ready for its fling with cocaine in the 1960s. Today, it is estimated that upwards of 50 million Americans, that is one in four, have used cocaine. In addition, another fifty thousand people use this substance for the first time each day. More than 6 million Americans use cocaine on a regular basis. Little wonder, then, that America as well as the other countries have declared a "War on Drugs." In this review, pharmacology of cocaine, major complications arising from its use, and efforts to curb its abuse are discussed.

Cocaine attenuates puberty acceleration in female house mice

The onset of puberty in female house mice is advanced by exposure to a male urinary pheromone. This study tested whether cocaine could modify the juvenile female mouse's response to this pheromone. Puberty acceleration, as measured by uterine weight change, is inhibited by daily SC administration of 30 or 40 mg/kg body weight cocaine HCl between 20 and 26 days of age. Two daily injections of 20 mg/kg cocaine reduced both uterine development and body weight gain. Thus, cocaine may reduce an animals' reproductive fitness by isolating it from its social environment. At higher doses, cocaine can delay body growth, as well as the onset of puberty.

Effects of repeated administration of cocaine to the fetal sheep in the last days of pregnancy

OBJECTIVE

There are no reports on the direct effects of repeated cocaine administration to the fetus in late pregnancy. The aim of our study was therefore to examine the effects of repeated fetal exposure to cocaine on fetal development.

STUDY DESIGN

Ten fetal sheep were instrumented at 123 +/- 1 days' gestation. Five fetuses received a single daily intravenous injection of cocaine (2 mg/kg) commencing at 130 to 131 days of gestation until delivery at 132 to 144 days of gestation; those fetuses were compared with fetuses that did not receive cocaine (n = 5).

RESULTS

Basal fetal arterial blood gas values, blood pressure, heart rate, and nuchal and diaphragmatic activities did not change in the days preceding labor. Fetal arterial PO2 fell after cocaine administration, but this was significant only on the first day. Cocaine induced consistent significant alterations in fetal pH and PCO2, blood pressure, and heart rate. During labor cocaine stimulated diaphragmatic and nuchal muscle activity when compared with the other days. There was no increase in diaphragmatic and nuchal muscle activity in the controls.

CONCLUSION

Our studies indicate that in fetal sheep the cardiovascular and blood gas response to cocaine in late pregnancy is not altered by repeated exposure to cocaine and that cocaine stimulates fetal breathing during labor.

Anaesthetic management of a parturient with myocardial infarction related to cocaine use

Cocaine abuse is common among parturients with an incidence of 11.8 to 20%. Myocardial infarction is a rare and lethal event during pregnancy with an incidence of 1 in 10,000 pregnancies. We present the anaesthetic management of a parturient of 36 wk gestation who suffered a myocardial infarction nine hours before delivery which was temporally related to "crack" cocaine use. The patient's cardiovascular system became unstable following cocaine use, and she required mechanical ventilatory support and pharmacologic stabilization guided by invasive haemodynamic monitoring. This patient survived a non-Q wave myocardial infarction, but the prognosis of peripartum myocardial infarction remains poor with a mortality rate of 30-40% which is increased if the infarction occurs in the third trimester or postpartum period. The optimal mode and timing of delivery after myocardial infarction is unresolved. The association between cocaine use and myocardial infarction was first described in 1982, and cocaine remains unique among local anaesthetics in its ability to compromise the cardiovascular system through both sympathomimetic effects and vasoconstrictive effects on coronary arteries. Because of the prevalence of substance abuse, cocaine use should be considered in the differential diagnosis of sudden cardiovascular compromise in parturients.

Hemodynamic effects of centrally administered, norcocaine in the rat

Norcocaine is the N-demethylated metabolite of cocaine. It is present in the CNS and is reported to be pharmacologically active. The present study was designed to evaluate the cardiovascular actions of norcocaine following central administration. Wistar Kyoto (WKY) rats were anesthetized with pentobarbital and instrumented for measurement of blood pressure and renal and hindlimb blood flow (via Doppler flowprobes). A cerebroventricular cannula was placed in the lateral ventricle for drug administration. Cocaine or norcocaine was administered centrally in a dose range of 0.025 to 4.0 mg/kg. Under the above experimental conditions, 4.0 mg/kg of norcocaine decreased blood pressure without a significant change in either hind limb or renal blood flow. Central administration of cocaine also produced a similar depressor response. In conscious, unrestrained rats, cocaine produced a pressor response while norcocaine did not significantly alter blood pressure. The depressor response to both cocaine and norcocaine in the anesthetized animal is speculated to be due to the local anesthetic properties of the drugs.

Effects of cocaine on oxygen consumption and mitochondrial respiration in normoxic and hypoxic mice

The administration of cocaine hydrochloride intraperitoneally (25 mg/kg) produces a drop in VO2 in both normoxic and hypoxic mice. The critical PO2 is also decreased and so is the body temperature. The mitochondrial respiration shows a large fall in ST3 and RCR. The addition of cocaine in-vitro to the incubating medium induces changes in the mitochondrial respiration similar to those found after in-vivo administration. This report shows that in addition to its in-vivo actions cocaine alters the respiratory function of the isolated liver mitochondria.

Emergency room evaluation of cocaine-associated neuropsychiatric disorders

The widespread abuse of cocaine has produced an alarming number of cocaine-related emergency room visits in the last several years. The authors discuss the various issues involved in emergency rom evaluation of patients who abuse cocaine and manifest signs and symptoms suggesting neuropsychiatric disease. Appropriate triage is emphasized, and a discussion of impediments to the accurate assessment of these patients ensues. The unique features of cocaine-induced mood, psychotic, and organic disorders are then detailed and contrasted with other functional and organic disorders. Strategies for the emergency room treatment of patients exhibiting symptomatology consistent with cocaine intoxication and withdrawal are outlined. The issues of psychiatric comorbidity and dual diagnosis in the cocaine-abusing population are examined. In addition, the neurological complications associated with the use of cocaine are reviewed. Finally, emerging data from single photon emission computerized tomography (SPECT) analysis of cocaine abusers is reported.

Excitatory amino acid receptor antagonists: potential implications for cardiovascular therapy and cocaine intoxication

A hypothesis is offered which suggests that excitatory amino acid (EAA) receptor antagonists have a potential role in the management of cardiac and cardiovascular pathophysiology resulting from increased central autonomic discharge. This suggestion is based on evidence that endogenous EAA release occurs following cerebral hypoxic insults, that cerebral hypoxia is associated with a high incidence of circulatory damage and that local intracerebral injection of EAA receptor agonists stimulates cardiovascular function and causes cardiac necrosis. Clinical events that can be linked to cerebral hypoxia, EAA release and production of cardiac pathology include intracerebral hemorrhage, cerebral trauma and stress. Cocaine intoxication may also involve central EAA release and experimental data are presented which demonstrate that pre-treatment with the EAA receptor antagonist, MK-801, can antagonize cocaine toxicity in the conscious rat. Antagonists at EAA receptors may be clinically useful in the management of disease states where heart-brain interactions contribute to morbidity and mortality.

Effects of cocaine on pial arterioles in cats

We used the closed cranial window technique to observe the responses of pial arterioles to topical application of cocaine in 29 anesthetized cats. Alterations in arteriolar diameter were dependent on the concentration of cocaine applied. Cocaine dissolved in artificial cerebrospinal fluid at concentrations of 10(-8) or 10(-7) M was without effect. Concentrations of 10(-6) and 10(-5) M produced dilation (4.9 +/- 1.5% [mean +/- SEM] and 5.9 +/- 2.0%, respectively) in large arterioles (greater than 100 microns) but no significant change in the diameter of small arterioles (less than 100 microns). A concentration of 10(-4) M dilated both large and small arterioles (20.3 +/- 3.1% and 12.0 +/- 7.1%, respectively). Pretreatment with 1 mg/kg i.v. propranolol blocked the increase in pial arteriolar diameter after application of 10(-4) M cocaine and produced significant vasoconstriction in small arterioles (-8.3 +/- 3.1%). Cocaine produces vasodilation of cat cerebral arterioles. This effect appears to be mediated, at least in part, by mechanisms that depend on stimulation of beta-adrenergic receptors.