Lateral hypothalamic stimulation in satiated rats: the rewarding effects of self-induced drinking.

It is well known that thirsty rats will press a lever for water. The purpose of the present experiment was to demonstrate that, when water is freely available, nonthirsty rats will press a lever for thirst. Three satiated rats, bearing permanently implanted electrodes, were trained to press a lever which caused stimulation to be applied to an area of the lateral hypothalamus which induces thirst. The animals were tested with and without water available. Two of the rats pressed the lever to induce thirst only when water was available. Thus, thirst-inducing stimulation was not rewarding by itself, but only in combination with drinking.

Lateral hypothalamic stimulation: inhibition of aversive effects by feeding, drinking, and gnawing.

The opportunity to engage in feeding, drinking, and gnawing behavior facilitated by localized hypothalamic stimulation can delay the onset of the aversive effects of the stimulation and may completely suppress them. This suggests that the aversive effects of the stimulation are due to the excessive of the stimulation are due to the exessive arousal of a drive.

Ethanol-1-C14 metabolism in alcoholics and nonalcoholics.

Metabolism of ethanol-1-C(14) was assessed in a group of alcoholic and nonalcoholic male subjects. All subjects were screened for absence of physical derangement. Subjects were also carefully matched by dietary, social, and environmental criteria. No differences in rate of output of C(l4)CO(2) were detected after ingestion of alcohol which produced concentrations of 50 to 60 milligrams of alcohol per 100 milliliters of blood. These data do not support the hypothesis that alcoholics metabolize ethanol more rapidly than nonalcoholics do.

Tongue cooling: a new reward for thirsty rodents.

Thirsty rodents will persistently lick a stream of dry air pumped through a standard drinking tube. This air-licking is attenuated by experimental manipulations which reduce the evaporative cooling of the tongue and mouth produced by the airstream. This suggests that such cooling is itself an effective reward for thirstry rodents. We tested this hypothesis by presenting thirsty rodents with a piece of cold, dry metal. Different species spent from 9 to 40 percent of their session time licking the cold metal. When deprived of water hamsters reared from birth without access to drinking water licked cold metal in preference to metal maintained at room or body temperature. This preference was approximately equal to that of littermates reared normally. We conclude that tongue cooling is a primary reward for thirsty rodents.

Blood concentrations of acetaldehyde and ethanol in chronic alcoholics.

Fifteen adult male alcoholic volunteers were studied before, during, and after a 10- to 15-day period of experimentally induced intoxication. Blood acetaldehyde concentrations ranged from 0.11 to 0.15 and from 0.04 to 0.08 milligrams per 100 milliliters when blood ethanol concentrations ranged from 1 to 400 milligrams per 100 milliliters after consumption of bourbon or grain ethanol, respectively. No dose or dose-time relationships were found between blood ethanol concentrations and blood acetaldehyde concentrations during any phase of this study.

Buprenorphine suppresses heroin use by heroin addicts.

Heroin-dependent men were given buprenorphine (a partial opiate agonist-antagonist) or a placebo under duoble-blind conditions on a clinical research ward where they could acquire heroin (21 to 40.5 milligrams per day, intravenously). Buprenorphine significantly (P less than .001) suppressed the self-administration of heroin over 10 days. Control subjects took between 93 and 100 percent of the available heroin. The effects of buprenorphine were dose-dependent; a dose of 8 milligrams per day reduced heroin use by 69 to 98 percent; a dose of 4 milligrams per day reduced heroin use by 45 percent. Termination of buprenorphie maintenance did not result in opiate withdrawal signs or symptoms. The subjects liked buprenorphine and indicated that it was preferable to methadone or naltrexone. Buprenorphine should be a safe and effective new pharmacotherapy for heroin dependence.

Alcohol-induced hyperlipidemia and beta lipoproteins.

Alcohol addicts with a primary type IV hyperlipoproteinemia show a striking elevation of triglycerides in the serum during long periods of alcohol consumption as compared with controls, without an accompanying significant increase in free fatty acids in the serum. These data suggest that this genetically related lipid abnormality may be a significant factor in the pathogenesis of alcohol hyperlipemia and the alcohol-induced fatty liver.

Buprenorphine suppresses cocaine self-administration by rhesus monkeys.

Cocaine abuse has reached epidemic proportions in the United States, and the search for an effective pharmacotherapy continues. Because primates self-administer most of the drugs abused by humans, they can be used to predict the abuse liability of new drugs and for preclinical evaluation of new pharmacotherapies for drug abuse treatment. Daily administration of buprenorphine (an opioid mixed agonist-antagonist) significantly suppressed cocaine self-administration by rhesus monkeys for 30 consecutive days. The effects of buprenorphine were dose-dependent. The suppression of cocaine self-administration by buprenorphine did not reflect a generalized suppression of behavior. These data suggest that buprenorphine would be a useful pharmacotherapy for treatment of cocaine abuse. Because buprenorphine is a safe and effective pharmacotherapy for heroin dependence, buprenorphine treatment may also attenuate dual abuse of cocaine and heroin.

Alcohol self-administration disrupts reproductive function in female macaque monkeys.

Female macaque monkeys self-administered high doses of alcohol (2.9 to 4.4 grams per kilogram per day) for 3 to 6 1/2 months. Amenorrhea, atrophy of the uterus, decreased ovarian mass, and significant depression of luteinizing hormone levels were associated with chronic alcohol intoxication. Reproductive system failure in female primates following self-induced dependence on alcohol parallels the results of clinical studies of alcoholic women.

The effects of inhaled L-methamphetamine on athletic performance while riding a stationary bike: a randomised placebo-controlled trial.

OBJECTIVE: L-methamphetamine (the non-abused isomer of methamphetamine) is banned in athletic competition because it may improve athletic performance, but there are no studies assessing its effects on performance. In the United States L-methamphetamine is formulated in the non-prescription Vick's Vapor Inhaler (VVI) nasal decongestant. VVIs sold elsewhere (we used ones from the UK) contain similar inactive ingredients (menthol, camphor and Siberian pine oil) but no L-methamphetamine. This study tested the effects of inhaled L-methamphetamine delivered from a widely available non-prescription product on athletic performance. DESIGN: In a 2-session double-blind placebo-controlled study 12 participants (ages 14-17) were dosed with 4 (session 1) and 12 (session 2) inhalations from VVIs with (USA) or without (UK) L-methamphetamine and then performed two 20 minute rides on a stationary bike with rides separated by a 30 minute rest. OUTCOME MEASURE: The main outcome measure was miles travelled during each 20 minute ride. Secondary outcome measures included postride urine toxicology; heart rate and blood pressure before, 1, 5 and 10 minutes postride; energy, performance, endurance, and ability to breathe; and VVI preference. Data were analysed using Excel statistical macros. RESULTS: After approximately 16 microg L-methamphetamine distance travelled was 5.26 (SD 0.53) miles vs 5.30 (0.55) with placebo; p = 0.81. After approximately 48 microg L-methamphetamine distance travelled was 5.30 (0.51) vs 5.35 (0.43) with placebo; p = 0.85. The approximately 16 microg dose increased systolic blood pressure from 72.6 (4.3) to 79.6 (6.6) mm Hg (p = 0.03) at 5 minutes postride but there were no other differences in outcomes. CONCLUSIONS: Modest doses of inhaled L-methamphetamine probably do not improve athletic performance but do minimally raise diastolic blood pressure.

Disruption of transforming growth factor-beta signaling through beta-spectrin ELF leads to hepatocellular cancer through cyclin D1 activation.

Transforming growth factor-beta (TGF-beta) signaling members, TGF-beta receptor type II (TBRII), Smad2, Smad4 and Smad adaptor, embryonic liver fodrin (ELF), are prominent tumor suppressors in gastrointestinal cancers. Here, we show that 40% of elf(+/-) mice spontaneously develop hepatocellular cancer (HCC) with markedly increased cyclin D1, cyclin-dependent kinase 4 (Cdk4), c-Myc and MDM2 expression. Reduced ELF but not TBRII, or Smad4 was observed in 8 of 9 human HCCs (P<0.017). ELF and TBRII are also markedly decreased in human HCC cell lines SNU-398 and SNU-475. Restoration of ELF and TBRII in SNU-398 cells markedly decreases cyclin D1 as well as hyperphosphorylated-retinoblastoma (hyperphosphorylated-pRb). Thus, we show that TGF-beta signaling and Smad adaptor ELF suppress human hepatocarcinogenesis, potentially through cyclin D1 deregulation. Loss of ELF could serve as a primary event in progression toward a fully transformed phenotype and could hold promise for new therapeutic approaches in human HCCs.

The effects of antioxidants in the senescent auditory cortex.

We investigated whether a 2-month dietary supplementation of antioxidants, in the form of blueberry phytochemicals, could reverse or retard the age-related decline in temporal processing speed observed in the aged rat. To this end, extracellular single unit responses to frequency modulated (FM) sweeps were recorded in the primary auditory cortex (AI) of aged rats that had been placed on either a blueberry-supplemented or control diet 2 months prior to the physiological recordings. Results showed that most cells recorded from the blueberry-fed rats responded most vigorously to fast FM sweeps, similar to that observed in young rats. In contrast, the majority of cells recorded from the control rats showed a preference for slow FM sweep rates. These results suggest that age-related changes in temporal processing speed in A1 may be reversed by dietary supplementation of blueberry phytochemicals.

Left ventricular function immediately after intravenous cocaine: a quantitative two-dimensional echocardiographic study.

OBJECTIVES: We tested the hypothesis that intravenous cocaine, in doses commonly self-administered in nonmedical settings, causes acute myocardial ischemia and left ventricular dysfunction. BACKGROUND: Cocaine-induced cardiac complications are responsible for a growing number of deaths in young people, but the mechanism by which cocaine induces these complications is unclear. METHODS: We performed 12-lead electrocardiography and quantitative two-dimensional echocardiography in 20 subjects before and after single intravenous doses of high dose cocaine (1.2 mg/kg body weight), low dose cocaine (0.6 mg/kg) and placebo. RESULTS: At 2 to 7 min after cocaine administration, the rate-pressure product was increased significantly from baseline (high dose 73%, low dose 63%, placebo 8%, p < 0.001 for either dose vs. placebo). During this time, electrocardiography demonstrated dose-related nonspecific changes (high dose in 14 of 20 subjects, low dose in 9 of 20 subjects, placebo in 2 of 20 subjects, p < 0.002 for either dose vs. placebo). In contrast, echocardiography showed that the frequency of hyperdynamic left ventricular wall segments doubled after high dose cocaine compared with placebo (34% [108 of 318] vs. 16% [51 of 319], respectively, p = 0.0001) but that there was no change in either left ventricular ejection fraction (high dose 66 +/- 9%, placebo 67 +/- 6%, p = NS) or wall motion score index (high dose 0.67 +/- 0.44, placebo 0.85 +/- 0.30, p = NS). CONCLUSIONS: We conclude that intravenous cocaine, in doses commonly self-administered in nonmedical settings, does not cause acute myocardial ischemia or left ventricular dysfunction. We speculate that cocaine-induced cardiac complications are caused by idiosyncratic coronary artery vasospasm, by exceptionally high dosages or by cocaine-induced coronary artery thrombosis.

Marijuana consumption and tolerance to physiological and subjective effects.

The relation between marijuana consumption and the development of tolerance was investigated during a 31-day study. Volunteers with a history of moderate or heavy marijuana use were given access to one-gram (2.1% delta9 tetrahydrocannabinol [THC]) marijuana cigarettes during a 21-day smoking period. Both groups tended to increase consumption during this time. Heavy users averaged 5.7 cigarettes per day and indicated a progressive decline in ratings of intoxication and duration of pulse rate effect. Moderate users averaged 3.2 cigarettes per day but showed no changes in either of these reactions during this time. Results suggested that tolerance does not develop to the two most reliable indexes of marijuana intoxication unless heavy doses of delta9 THC are self-administered repeatedly. Also, the tendency to increase consumption during this time is not necessarily associated with the development of tolerance.

Cocaine-induced erythrocytosis and increase in von Willebrand factor: evidence for drug-related blood doping and prothrombotic effects.

BACKGROUND: Mechanisms that mediate cocaine-induced cardiovascular events following vasoconstriction are incompletely understood. OBJECTIVE: To examine the effects of cocaine in moderate doses on hematologic and hemostatic parameters that influence blood viscosity and thrombotic potential. METHODS: Changes in hemoglobin concentration, hematocrit, and red blood cell counts were measured in human subjects who met Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria for long-term cocaine abuse, before and sequentially after moderate intranasal and intravenous doses of cocaine. Hemostatic parameters, including von Willebrand factor, fibrinolytic activity, fibrinogen, plasminogen activator inhibitor antigen, and tissue-type plasminogen activator antigen, were sequentially measured after intravenous cocaine or saline placebo with cardiac troponin subunits T and I. RESULTS: Hemoglobin level (P= .002), hematocrit (P =.01), and red blood cell counts (P = .04) significantly increased from 4% to 6% over baseline from 10 to 30 minutes after intranasal (n = 14) and intravenous (n = 7) cocaine administration in doses of 0.9 mg/kg and 0.4 mg/kg, respectively, with no change in white blood cell or platelet counts. There was a significant increase (P =.03) in von Willebrand factor from 30 to 240 minutes, peaking at 40% over baseline following intravenous cocaine administration in a dose of 0.4 mg/kg (n = 12), with no change after 0.2 mg/kg (n = 3) or placebo (n = 6). Other hemostatic factors, creatinine, blood urea nitrogen, and cardiac troponin subunits T and I showed no changes. CONCLUSIONS: Cocaine induced a transient erythrocytosis that may increase blood viscosity while maintaining tissue oxygenation during vasoconstriction. An increase in von Willebrand factor without a compensatory change in endogenous fibrinolysis may trigger platelet adhesion, aggregation, and intravascular thrombosis.

Alcohol effects on naltrexone-induced stimulation of pituitary, adrenal, and gonadal hormones during the early follicular phase of the menstrual cycle.

Chronic alcohol abuse in women is associated with severe derangements of menstrual cycle regularity. However, acute alcohol ingestion has no effect on pituitary-gonadal secretory function. The purpose of this study was to determine whether acute alcohol ingestion altered the effects of naltrexone, a long-acting opioid antagonist, on pituitary, adrenal, and gonadal hormones in normal women. Fourteen women were studied during the early follicular phase (between days 2 and 4) of their menstrual cycle. Plasma LH, PRL, estradiol, progesterone, and cortisol concentrations were measured before and after administration of 50 mg naltrexone, orally, and alcohol or placebo solution given 1 h after naltrexone, under double blind conditions. Naltrexone significantly increased mean plasma LH (P = 0.02), PRL (P = 0.003), E2 (P less than 0.03), and cortisol (P less than 0.001) levels. Alcohol significantly augmented the naltrexone-stimulated increases in plasma LH (P = 0.006), estradiol (P less than 0.004), and cortisol (P less than 0.001) levels and significantly decreased plasma progesterone levels (P = 0.001). Plasma PRL increased (P = 0.001) to the same extent after naltrexone and alcohol ingestion or naltrexone and placebo. We conclude that alcohol enhances naltrexone-induced increases in plasma gonadotropins and adrenal and gonadal steroid hormones in women during the early follicular phase of the menstrual cycle.

Cocaine effects on luteinizing hormone-releasing hormone-stimulated anterior pituitary hormones in female rhesus monkey.

The effects of acute cocaine administration on synthetic LHRH-stimulated anterior pituitary hormones (LH, FSH, and PRL) were studied in 6 female rhesus monkeys during the follicular phase of the menstrual cycle (days 4-7). Integrated plasma samples were collected every 10 min for 40 min before iv administration of cocaine (0.4 or 0.8 mg/kg) or an equal volume of vehicle control solution. Synthetic LHRH (100 micrograms, iv) was administered 10 min after cocaine or placebo-cocaine administration, and 10 plasma samples were collected for an additional 100 min. LHRH stimulated a significant increase in LH within 10 min after placebo-cocaine administration (P less than 0.05) and after each dose of cocaine (P less than 0.0001). Cocaine (0.4 mg/kg) significantly enhanced LHRH stimulation of LH compared to placebo or 0.8 mg/kg cocaine administration (P less than 0.01). FSH increased significantly within 20-30 min after LHRH alone (P less than 0.008) and after 0.4 mg/kg cocaine (P less than 0.0001). LHRH-stimulated FSH levels also were significantly higher after 0.4 mg/kg cocaine than after placebo or 0.8 mg/kg cocaine (P less than 0.01). These data indicate that cocaine does not suppress LHRH stimulation of pituitary gonadotropins, and low doses of cocaine significantly enhance LH and FSH release. Consequently, cocaine does not compromise anterior-pituitary function at the level of the gonadotroph and may stimulate hypothalamic release of endogenous LHRH. PRL levels were unchanged by LHRH and placebo-cocaine administration. After LHRH and cocaine administration, PRL levels decreased significantly (P less than 0.05-0.01) and remained suppressed throughout the 110-min postcocaine sampling period. These data indicate that cocaine's significant suppression of PRL is not blocked by LHRH. These findings are consistent with dopaminergic inhibitory control of PRL and suggest that cocaine's inhibition of dopamine reuptake down-regulates pituitary lactotroph activity in rhesus monkey.

Cocaine effects on pulsatile secretion of anterior pituitary, gonadal, and adrenal hormones.

Pulse frequency analysis of LH, PRL, testosterone, and cortisol was carried out with the Cluster Analysis Program in eight male cocaine abusers and eight aged-matched normal men. Four of the eight cocaine abusers had hyperprolactinemia (range, 22.08-44.65 micrograms/L). Cocaine users as a group had significantly higher mean peak height (P less than 0.02) than control subjects. Cocaine users with hyperprolactinemia had higher mean peak height than control subjects or cocaine users with normal PRL levels (P less than 0.01). Cocaine users with hyperprolactinemia also had higher mean amplitude increments than control subjects (P less than 0.02). Cocaine users with hyperprolactinemia had a higher mean valley than controls (P less than 0.01) and cocaine users with normal PRL levels (P less than 0.03). However, there were no significant differences in PRL peak frequency, peak duration, or interpulse intervals between cocaine users with or without hyperprolactinemia and control subjects. There were minimal differences between cocaine users and control subjects in pulse frequency analysis of LH parameters; the small differences in mean LH levels and average interpulse interval were not in the abnormal range and were probably not biologically significant. No differences between cocaine users and controls were detected for pulse frequency analysis of testosterone or cortisol. Cocaine-induced hyperprolactinemia may contribute to disorders of sexual and reproductive function in men who abuse the drug, and recent reports that PRL modulates immune function suggest that cocaine-induced derangements of PRL secretion may also contribute to cocaine-related comorbidity in infectious disease. Since cocaine users with hyperprolactinemia had a higher mean valley as well as a higher peak pulse PRL height than control subjects, but did not have greater PRL pulse frequencies, we conclude that hyperprolactinemia in these men may be due to a cocaine-induced derangement of dopaminergic inhibition of basal PRL secretion.

Effects of cocaine and corticotropin-releasing factor on pulsatile ACTH and cortisol release in ovariectomized rhesus monkeys.

Cocaine stimulates ACTH secretion by a corticotropin-releasing factor (CRF)-dependent mechanism in male rats, rhesus monkeys, and humans. To determine the generality of this effect, we examined the effects of acute cocaine administration on the pulsatile release of ACTH and cortisol in three ovariectomized (OVX) rhesus monkeys and compared its effects to stimulation with CRF. Venous blood samples were collected at 2-min intervals for 60 min before and after iv administration of cocaine (0.4 and 0.8 mg/kg) and CRF (1.0 and 10 micrograms/kg). Cluster analysis procedures were used to evaluate the pulsatile characteristics of ACTH and cortisol release. After placebo administration, an ACTH pulse frequency of 3 peaks/h was detected. After cocaine administration, plasma cocaine levels peaked at 92 +/- 3.0 and 201 +/- 60 ng/mL within 2 min. However, in contrast to normal intact males, cocaine did not stimulate the pulsatile release of ACTH in OVX females. Cocaine (0.4 mg/kg) decreased ACTH incremental peak height and valley levels compared with pre-cocaine values, and a higher dose of cocaine produced no changes in ACTH release. Bolus injection of a low dose of CRF (1.0 micrograms/kg, iv) significantly increased ACTH incremental peak height (P < 0.05), and a higher dose of CRF (10 micrograms/kg) increased ACTH peak amplitude, percentage increase in peak amplitude, area under the peaks, and incremental peak heights as well as ACTH valley level and nadir (10 micrograms/kg, iv) (P < 0.05). ACTH pulse frequency did not change after CRF or cocaine administration. Pulsatile release of cortisol was 2.7 peaks/h under placebo conditions and did not change after cocaine or CRF administration. Cortisol pulse amplitude was increased after low and high doses of CRF. High doses of CRF (10 micrograms/kg) also increased the mean level of cortisol valleys. In summary, we found that CRF but not cocaine stimulated pulsatile ACTH and cortisol release in OVX rhesus monkeys. The profound ACTH response to CRF challenge suggests that the CRF sensitivity and the ACTH release capacity of the anterior pituitary corticotroph cells were intact. The lack of stimulatory effects of cocaine on the hypothalamic-pituitary-adrenal axis in OVX monkeys, in contrast to normal male monkeys, may reflect the absence of gonadal steroids.