Effects of cocaine and amphetamine on the metabolism of tryptophan and 5-hydroxytryptamine in mouse brain in vivo

In vitro release of [3H]5-hydroxytryptamine from fetal and maternal brain by drugs of abuse

Cortical synaptosomes were prepared from pregnant dams (GD-17) and rat fetuses (ED-17), loaded with [3H]5-HT and assayed to evaluate release mediated by cocaine (COC), fenfluramine (FEN) and 3,4-methylenedioxymethamphetamine (MDMA). COC and FEN elicited a high-affinity (10(-9) M) release response in fetal tissue which was not apparent in the dam. MDMA-induced release was similar in magnitude in both tissue types. Consequently, the release of 5-HT from developing neurons may be one mechanism by which COC and FEN elicit their teratogenetic effects in utero.

Sexually dimorphic effects of prenatal cocaine on adult sexual behavior and brain catecholamines in rats

Exposure to cocaine in utero (10 mg/kg twice a day on days 11-18 of gestation) differentially altered adult sexual behavior, brain catecholamine levels and perhaps open field activity in male and female rats. Female rats exposed to cocaine were significantly inhibited in their sexual behavior when compared to saline-exposed controls. In contrast, males exposed prenatally to cocaine exhibited normal or even facilitated sexual behavior. In particular, the significantly shorter post-ejaculatory intromission intervals displayed by cocaine-exposed males indicated that these animals might have enhanced sexual arousal or motivation. In tests for open field activity, males consistently showed higher levels of rearing behavior than females. Prenatal cocaine tended to reduce rearing in females, but this effect was not significant. Cocaine-exposed male rats had significantly higher norepinephrine and dopamine levels in the preoptic area than saline-exposed controls, whereas cocaine did not affect catecholamine content in male hypothalamus, striatum, cortex or cerebellum. Cocaine- and saline-exposed females had similar catecholamine levels in all brain regions. These results suggest that exposure of developing animals to modest doses of cocaine during mid to late gestation results in long-lasting, sexually dimorphic alterations of adult sexual behavior and brain catecholamines in rats.

Hyperthermia in sauna is unable to increase the plasma levels of ACTH/cortisol, beta-endorphin and prolactin in cocaine addicts

In order to establish possible different reactions between normal subjects and cocaine addicts to short term exposure to heat, thermal, cardiovascular and pituitary hormonal responses to hyperthermia in sauna were measured in 8 male cocaine addicts (studied after 14 days of abstinence) and in 8 age and weight matched normal men. Subjects sat for 30 min in a sauna room, where the temperature was 90 C and the relative humidity 10%. Physiological and hormonal parameters were measured just before and after sauna and after 30 min of rest at normal (21 C) room temperature. Significant and comparable increments in systolic and diastolic blood pressure, pulse rate and sublingual temperature were observed in the two groups at the end of sauna. All these parameters decreased to normal values after 30 min of rest at normal room temperature. Before sauna, ACTH, cortisol and beta-endorphin levels were similar in the two groups, whereas plasma prolactin concentrations were significantly higher in cocaine addicts. All examined hormones rose significantly in the normal controls at the end of sauna. All hormones, except cortisol, returned to the basal levels after 30 min at normal room temperature. In contrast, no significant hormonal responses to hyperthermia were observed at any time point in cocaine addicts. These data do not provide evidence of alterations in the cardiovascular and thermal adaptive responses to hyperthermia in cocaine abusers. On the other hand, the results show an impairment of the ACTH/cortisol, beta-endorphin and prolactin responses to hyperthermia in cocaine addicts.(ABSTRACT TRUNCATED AT 250 WORDS)

Prenatal cocaine exposure disrupts the development of the serotonergic system

Prenatal cocaine exposure has been found to result in a number of neurobehavioral abnormalities in both clinical and laboratory studies. We have previously shown that cocaine inhibits the growth of developing serotonin neurons in culture. This study examines the effects of cocaine on the developing serotonin system in vivo. Pregnant rats were injected with cocaine (40 mg/kg s.c.) from gestational day 13 to parturition. One group of rats was additionally injected on postnatal days 1-5 with cocaine (10 mg/kg s.c.). [3H]Paroxetine, a selective ligand for the serotonin uptake carrier, was used to quantify serotonin terminal fiber density at one day, one week, and four weeks postnatal. Cocaine exposure was found to significantly decrease [3H]paroxetine-labelled sites and thus the density of serotonin fibers in the cortex and hippocampus at one day and one week postnatal. By four weeks postnatal, no significant effect was observed, indicating that a recovery had occurred. Serotonin immunocytochemistry performed at one month revealed normal fiber distribution in the cortex but a loss of fibers in the CA1 and CA2 hippocampal fields. Postnatal treatment alleviated the effects of prenatal cocaine exposure, resulting in [3H]paroxetine binding levels at one week which were comparable to and, in the cortex, even higher than those of saline controls. We conclude that cocaine delays the maturation of the serotonin system when administered prenatally but may accelerate maturation when administered both pre- and postnatally.

Recent Advances in Pharmacological Research on Alcohol

Alcohol dependence is a major public health problem. Studies have shown that a person dependent on alcohol often coabuses other substances, such as cocaine. Cocaine is a powerful stimulant whereas ethanol is generally considered to be a depressant, with some stimulating properties. The subjective effects of these two substances in a dependent individual may often appear to be more similar than they are different. Animals also self-administer both substances. Basically, although both substances have anesthetic properties and both act to functionally increase catecholaminergic function, especially that of dopamine, there are some differences in their actions. Both alcohol and cocaine have various effects on several neurotransmitters and systems, which ultimately interact to produce the feeling of well-being avidly sought by many individuals today. This drive often eventually produces a dependence which has associated social and medical consequences. It seems likely that the neurochemical changes that ensue following abuse of these substances underlie the phenomena of dependence, tolerance, and subsequent withdrawal. The apparent similarities and differences between these two substances will be reviewed in this chapter.

Blockade of tolerance to morphine analgesia by cocaine

Tolerance to morphine analgesia was induced in male Sprague-Dawley rats by s.c. implantation of a morphine base pellet (75 mg) on the first and second day and determining the magnitude of tolerance 72 h after the first implant by s.c. injection of a test dose of morphine (5 mg/kg). Implantation of a cocaine hydrochloride pellet (25 mg), concurrently with morphine pellets or of a cocaine hydrochloride (50 mg) pellet after the development of tolerance, blocked both the development and expression of morphine analgesic tolerance. In morphine-pelleted animals pretreatment for 3 days with desipramine or zimelidine or phenoxybenzamine but not haloperidol produced no significant morphine tolerance. Pretreatment with a combination of desipramine and zimelidine, however, was as effective as cocaine in blocking morphine tolerance. Alpha-Methyl-p-tyrosine methyl ester counteracted the effect of cocaine in blocking morphine tolerance and potentiated the tolerance development. Blockade of morphine tolerance by cocaine was reinforced and facilitated by pretreatment with fenfluramine or p-chlorophenylalanine ethyl ester and to a lesser extent by clonidine and haloperidol. Acute administration of fenfluramine or zimelidine or a combination of desipramine and zimelidine or alpha-methyl-p-tyrosine methyl ester or p-chlorophenylalanine ethyl ester did not significantly affect morphine analgesia. The study suggests an important role of the concomitant depletion of both central noradrenaline and serotonin in the blockade of morphine tolerance by cocaine and stresses the importance of the counter-balancing functional relationship between these two neurotransmitters in the central nervous system.

Effects of prenatal cocaine exposure on behavior during the early postnatal period

Offspring of Sprague-Dawley dams injected SC with 40 mg/kg/3 cc cocaine HCl daily from gestational days 8-20, pair-fed dams injected with the vehicle alone and nontreated control dams were examined behaviorally during the early postnatal period. No significant differences were observed among the treatment conditions in maternal weight gain during pregnancy, duration of pregnancy, or number of live male and female pups/litter. Offspring body weights at birth and weaning, physical maturation and reflex development were not significantly affected by prenatal cocaine exposure. In contrast, neonates exposed prenatally to cocaine were observed to exhibit significant deficits in learning of an odor/milk association that nontreated offspring learned and retained for a 24 hr period. On postnatal day 12, cocaine offspring exhibited an increase in locomotor activity and attenuated wall climbing precipitated by footshock, in the absence of any alteration in sensitivity to footshock. Given that wall climbing has been previously shown to be strongly related to levels of catecholamine activity at this age, these data suggest the possibility that there may be some attenuation in catecholaminergic function in pups exposed gestationally to cocaine. The results of this study provide evidence that prenatal cocaine exposure may have an impact upon behavioral and cognitive function even during the early postnatal period. More work is needed to fully characterize the range of alterations observed and the neural mechanisms underlying these early exposure effects.

Cocaine influences beta-endorphin levels and release

Immunoreactive beta-endorphin (IR-BE) was measured in the plasma, anterior pituitary (AP), neurointermediate lobe of the pituitary (NIL) and hypothalamus of male rats treated chronically (once daily for ten days) with cocaine. Cocaine produced a consistent elevation in the concentration of IR-BE in the plasma, the AP and the NIL at doses of 2.5 - 20 mg/kg/ip. The release of IR-BE from the AP and the NIL was determined in vitro and was found to be increased by treatment with cocaine. Chronic administration of cocaine did not affect the concentration of IR-BE in the hypothalamus. Chromatographic analysis revealed that cocaine produced a slight decrease in the amount of beta-endorphin relative to beta-lipotropin in the AP. Beta-endorphin was the major form of IR-BE released by the AP and the sole constituent and secretory product of the NIL. These data indicate that chronic administration of cocaine stimulates the endogenous opiate system, elevating the levels of IR-BE in the pituitary and promoting beta-endorphin release.

Effects of L-cocaine on local cerebral glucose utilization in the rat

The 2-deoxy-D-[l-14C]glucose method was used to map the in vivo metabolic response (local cerebral glucose utilization. LCGU) to L-cocaine in the rat brain. Injections of L-cocaine HCl (30 mg/kg, i.p.) selectively enhanced LCGU in 5 out of 56 brain regions that were examined (caudate-putamen, globus pallidus, substantia nigra pars reticulata, subthalamic nucleus, cerebellar vermis), but 10 or 30 mg/kg L-cocaine reduced LCGU in the habenula. In general, the acute effects of L-cocaine on LCGU resembled previously reported effects of D-amphetamine and apomorphine.

New concepts in cocaine addiction: the dopamine depletion hypothesis

Euphoric properties of cocaine lead to the development of chronic abuse, and appear to involve the acute activation of central DA neuronal systems. This is based upon known effects of cocaine on DA neurons, and the role played by DA in reward states and self-stimulation behavior. With chronic cocaine use, neurotransmitter and neuroendocrine alterations occur. DA depletion is hypothesized to result from overstimulation of these neurons and excessive synaptic metabolism of the neurotransmitter. DA depletion may underlie dysphoric aspects of cocaine abstinence, and cocaine urges. Neurochemical disruptions caused by cocaine are consistent with the concept of "physical" rather than "psychological" addiction. Possible pharmacological interventions in cocaine addiction are outlined and the psychological approach to these patients is discussed.

The effects of amfonelic acid on 5-HT metabolism in rat brain

The non-amphetamine stimulant amfonelic acid (AFA), an inhibitor of dopamine (DA) uptake, has been found to increase the levels of tryptophan (TRYP) and 5-hydroxyindoleacetic acid (5-HIAA) in the rat c. striatum, cerebral cortex, and brain stem. Pretreatment with the DA antagonist haloperidol did not affect this action of AFA in the c. striatum, suggesting that it is independent of the effects of this compound on DA neurons. The duration of action of the effect of AFA on TRYP and 5-HIAA appeared to be longer than that of the increase of the striatal DA metabolites homovanillic acid and 3,4-dihydroxyphenylacetic acid. The increased 5-HIAA concentrations seemed only in part be due to a probenecid-like effect of AFA; evidence for an increased 5-HT synthesis, probably related to the increased TRYP concentrations, was also obtained. This biochemical effect of AFA seems to differ from those reported in the literature on amphetamine and other, related stimulating agents. It might be of interest to see whether corresponding behavioural differences between AFA and these agents can be found.

Neurochemical effects of cocaine following acute and repeated injection

Following repeated injection in the rat, cocaine decreased the concentration of serotonin in the septum-caudate and increased the metabolism of hypothalamic norepinephrine and also striatal dopamine to a lesser extent. Furthermore, cocaine significantly decreased the activity of the rate-limiting enzyme, tryptophan hydroxylase. In a comparative study d-amphetamine and methylphenidate were found to exert an effect opposite to cocaine in the activation of tryptophan hydroxylase. These findings indicate that cocaine may lower central serotonin function by decreasing its availability for neural transmission. This could account for the stimulation of locomotor activity observed after cocaine administration.