Biomedical subjects

Ann Ho

Publications and source records attributed to Ann Ho.

34 records · Page 2Linked to original sources

PubMed2003

Increased CRH mRNA levels in the rat amygdala during short-term withdrawal from chronic 'binge' cocaine.

There is evidence that suggests that increased corticotropin-releasing hormone (CRH) release in the central nucleus of the amygdala underlies the anxiogenic and stress-like consequences of withdrawal that are common in phenomenology to all drugs of abuse. The present studies were undertaken to determine levels of CRH mRNA in the amygdala, and also in the hypothalamus, frontal cortex and brainstem after short-term (2 days) and intermediate-term (10 days) cocaine withdrawal (with continued saline injections) from chronic (14 days) 'binge' pattern cocaine administration (3 x 15 mg/kg per day at hourly intervals). Confirming our recent finding of an activation of stress responsive hypothalamic-pituitary-adrenal activity during early cocaine withdrawal, there was a significant elevation of plasma corticosterone level after 2-day cocaine withdrawal. There was also a significant elevation of CRH mRNA levels in the amygdala, but not in the hypothalamus, frontal cortex or brainstem after 2-day cocaine withdrawal. A negative correlation between amygdalar CRH mRNA and plasma corticosterone levels was found in the 2-day cocaine withdrawn rats but not in control rats, suggesting that CRH neurons in the amygdala may be differentially responsive to glucocorticoids after chronic cocaine exposure and withdrawal. There were no changes in either plasma corticosterone or amygdalar CRH mRNA levels after 10-day cocaine withdrawal. Our findings of an increase in amygdalar CRH gene expression during early cocaine withdrawal support a potentially important role for amygdalar CRH activity in the anxiogenic and aversive consequences of withdrawal from cocaine during a time when humans are most subject to relapse.

Amygdala↗

PubMed2003

Suppressed prolactin response to dynorphin A1-13 in methadone-maintained versus control subjects.

Dynorphin A1-13, a shortened sequence of the natural peptide dynorphin A1-17, is a primarily kappa-opioid receptor-preferring peptide. Previously, we showed that dynorphin A1-13 administered to normal volunteers causes a prompt dose-dependent elevation in serum prolactin that may reflect a reduction in tuberoinfundibular dopaminergic tone. This study was conducted to determine whether tuberoinfundibular dopaminergic tone is reduced in methadone-maintained patients. Eight former heroin addicts on stable-dose methadone maintenance with no ongoing drug or alcohol abuse or dependence and 15 normal volunteer controls with no history of drug or alcohol dependence received dynorphin A1-13 intravenously at doses of 120 microg/kg and 500 microg/kg. Studies began one hour before methadone dosing to avoid the expected increase in prolactin that coincides with peak plasma levels of methadone. After intravenous dynorphin A1-13, a dose-response increase in serum prolactin, which peaked within 20 min, was observed in both groups. There was no difference in prolactin between the two groups at baseline or following a placebo. The prolactin response to each dose of dynorphin A1-13 was significantly lower in the methadone-maintained volunteers compared with the controls. These results suggest that tuberoinfundibular dopaminergic tone is altered in methadone-maintained subjects. It is unknown whether altered dopaminergic tone existed before opiate addiction, is a result of heroin addiction, or is reflective of methadone maintenance. Whether methadone-maintained subjects also have decreased dopaminergic response to dynorphin and other kappa-opioid receptor ligands in mesolimbic-mesocortical and nigrostriatal dopaminergic systems cannot be determined from this study.

Adult↗

PubMed2003

Quantification of multiple mRNA levels in rat brain regions using real time optical PCR.

TaqMan is significantly more sensitive than other methods of mRNA quantification and makes possible the simultaneous analysis of numerous genes in small brain regions. This technique was used to quantify levels of mRNAs of 21 genes in tissue extracts from caudate putamen and nucleus accumbens from individual rats after 1 day 'binge' cocaine or saline administration. Expression of glyceraldehyde-3-phosphate-dehydrogenase, cyclophilin and actin mRNAs as well as 18S ribosomal RNA were evaluated for normalization of levels of gene expression.

Animals↗

PubMed2003

Corticotropin-releasing factor testing reveals a dose-dependent difference in methadone maintained vs control subjects.

Opiate addiction is associated with abnormal function of the stress-responsive hypothalamic-pituitary-adrenal (HPA) axis. In general, addiction and withdrawal are associated with abnormal HPA responsivity as demonstrated by baseline, dexamethasone, and metyrapone testing. Following stabilization in methadone maintenance treatment, normalization of HPA axis responsivity is observed. To further investigate HPA axis function associated with heroin addiction and its treatment, saline placebo and human corticotropin-releasing factor (hCRF) were administered intravenously in two doses, one dose lower (0.5 microg/kg) and one dose higher (2.0 microg/kg) than the dose used in standard clinical diagnostics (100 microg), to 16 normal male volunteer controls (NV) and eight male stable-dose methadone-maintained former heroin addicts without ongoing drug or alcohol abuse or dependence (MM). Plasma adrenocorticotrophic hormone (ACTH) and cortisol levels were determined at serial time points. There was no difference in hormonal measurements between the two groups following placebo. NV as well as MM displayed a dose-response effect in plasma ACTH and cortisol levels. MM displayed a significantly greater increase in plasma ACTH levels than the NV following high-dose but not low-dose hCRF (p <0.05). There was no significant difference in plasma cortisol levels between the two groups following high-dose hCRF. Thus, despite earlier documented normalization of behavioral function and of several measures of neuroendocrine function during long-term methadone maintenance, some abnormalities in HPA axis responsivity that may be a consequence of heroin exposure, or that may have existed prior to the addiction, can persist during stable methadone treatment.

Adrenocorticotropic Hormone↗

PubMed2003

The Kreek-McHugh-Schluger-Kellogg scale: a new, rapid method for quantifying substance abuse and its possible applications.

The new Kreek-McHugh-Schluger-Kellogg scale ('KMSK scale') is designed to quantify self-exposure to opiates, cocaine, alcohol, and/or tobacco. Each section of the KMSK scale assesses the frequency, amount, and duration of use of a particular substance during the individual's period of greatest consumption. The scale also assesses the mode of use, whether the substance use is current or past, and whether each substance is the substance of choice. The administration time is under 5 min. In an initial validation study of this scale, 100 human subjects were administered the KMSK scale concurrently with the Structured Clinical Interview for DSM-IV (SCID-I DSM-IV version). The sensitivity and specificity were very good for opiates, cocaine, and alcohol use. In addition, the correlations between KMSK scores and the number of SCID-I criteria items met were excellent for opiates and cocaine and good for alcohol use. Nicotine dependence was not assessed in this study as there is no SCID-I nicotine criteria. These preliminary results show that the KMSK scale may have both construct validity similar to that of other established self-report measures and the potential to be an effective screening instrument for the assessment of a lifetime diagnosis of alcohol, opiate, or cocaine dependence.

Adult↗

PubMed2003

Alterations in hypothalamic-pituitary-adrenal axis activity and in levels of proopiomelanocortin and corticotropin-releasing hormone-receptor 1 mRNAs in the pituitary and hypothalamus of the rat during chronic 'binge' cocaine and withdrawal.

Tolerance to the stimulatory effects of cocaine on the hypothalamic-pituitary-adrenal (HPA) axis develops after chronic 'binge' cocaine exposure in the rat. This blunting of HPA axis activity in response to cocaine is associated with a cocaine-induced reduction of corticotropin-releasing hormone (CRH) mRNA level in the hypothalamus. There is limited information about the effects of withdrawal from chronic cocaine on HPA activity. The present studies were undertaken to determine levels of the HPA hormones adrenocorticotropic hormone (ACTH) and corticosterone across 10 days of withdrawal following chronic 'binge' pattern cocaine administration (3 x 15 mg/kg/day at hourly intervals) for 14 days. Male Fischer rats showed a significantly attenuated HPA axis response to chronic 'binge' pattern cocaine administration 30 min after the last injection on the 14th day, as measured by both plasma ACTH and corticosterone levels at the nadir time point. Twenty-four hours following the final administration of 'binge' cocaine (the 1st day of withdrawal), a significant elevation of plasma ACTH levels and a modest, but significant, elevation of plasma corticosterone levels were found at the nadir time point. This acute withdrawal-related activation of the hormones of the HPA axis was no longer found on the 10th day of withdrawal. In the anterior pituitary, levels of both proopiomelanocortin (POMC) and CRH-receptor 1 (R1) mRNAs were significantly higher than saline controls on the 14th day of chronic 'binge' cocaine and were at control levels on the 4th day of withdrawal. In the neurointermediate lobe of the pituitary, a sustained reduction in POMC mRNA levels was observed on the 3rd, 7th and 14th day of chronic 'binge' cocaine, but POMC mRNA was at control levels by the 4th day of withdrawal. In the hypothalamus, POMC mRNA levels showed a transient decrease on the 1st day of 'binge' cocaine with no change during chronic 'binge' cocaine or its withdrawal. CRH mRNA levels in the hypothalamus were not different from saline controls on the 1st and 4th days of withdrawal. Taken together, the present results show that after development of adaptation or tolerance to chronic 'binge' cocaine there is an increase in HPA activity during acute cocaine withdrawal. In addition to being associated with CRH input from the hypothalamus, the activation of the HPA axis by cocaine withdrawal may be, at least in part, due to the increased POMC and/or CRH-R1 gene expression observed in the anterior pituitary after chronic 'binge' cocaine.

Adrenal Glands↗

PubMed2003

Optimizing primer--probe design for fluorescent PCR.

TaqMan, a variation of fluorescent PCR, is a powerful tool for gene expression and polymorphism studies. Here we describe the design and evaluation of 27 new TaqMan primer-probe sets for rat genes that play a key role in neural signaling. These newly designed and synthesized probes were tested and then used for quantification of RNA isolated from rat brain. The usual length of common TaqMan probes is 25 bases or less. In these studies we constructed probes with lengths of 25-39 bases to span exon-exon junctions of nucleic acids to avoid the influence of DNA contamination upon the RNA quantification. The specific sequences at these positions required probes of these lengths to optimize hybridization. We found that the relocation of the quencher from the traditional 3' position to an internal one increases the sensitivity of probe up to 30 fold. Substitution of 6-carboxyfluorescein with Alexa Fluor 488 as fluorophore and TAMRA with non-fluorescent quencher dabcyl was also investigated. We also describe the evaluation of part of a newly designed set of 27 TaqMan primer-probes for the measurement of differences in gene expression levels in samples from the caudate putamen region of rat brain after 'binge' paradigm cocaine administration. Cocaine-induced alterations in expression of c-fos and preprodynorphin mRNAs measured by TaqMan were confirmed by ribonuclease protection assay.

Animals↗

PubMed2003

"Binge" cocaine differentially alters preproenkephalin mRNA levels in guinea pig brain.

Male Hartley guinea pigs were administered i.p. injections of cocaine or saline for 2 or 7 days in a "binge" paradigm. RNA was isolated from dissected brain regions and levels of preproenkephalin mRNA and total RNA were quantified by RNase protection assays. Following 2 days of "binge" cocaine administration, no significant alterations in preproenkephalin mRNA levels were detected in six brain regions. Following 7 days of cocaine administration, however, lower levels of preproenkephalin mRNA were observed in the nucleus accumbens and hypothalamus of cocaine-treated animals and higher levels in the frontal cortex and amygdala. These findings differed from previous studies in the rat, so an additional experiment was performed with animals treated at the 7 day time point. For increased statistical power, data from the two experiments were combined and examined by two-way ANOVAs; in this combined analysis, increases in preproenkephalin mRNA were observed in frontal cortex, amygdala, and hippocampus, decreases were found in the nucleus accumbens and hypothalamus, with no change in thalamus, caudate putamen, or cerebellum. These observed differences between guinea pigs and rats make this species an interesting model for neurobiological studies of cocaine-induced alterations in neuropeptide gene expression in the mammalian brain.

Animals↗

PubMed2003

Locomotion, stereotypy, and dopamine D1 receptors after chronic "binge" cocaine in C57BL/6J and 129/J mice.

We have shown that C57BL/6J and 129/J mice differ in their behavioral response to "binge" pattern cocaine (three daily injections of 15 mg/kg separated by 1 h). To determine if these differences persist during chronic binge cocaine administration, we examined the effects of 14-day binge pattern cocaine on home cage behavior. Since the dopamine D(1) receptor may be an important mediator of cocaine-induced locomotor activity, we examined binding to the dopamine D(1) receptor. Locomotor activity was increased by chronic binge cocaine in C57BL/6J (P<.0001) but not in 129/J mice. C57BL/6J mice developed tolerance to the locomotor-activating effects of cocaine. Stereotypic responses were greater in C57BL/6J than in 129/J mice (P=.03), with neither tolerance nor sensitization in either strain. Dopamine D(1) receptor binding in the nucleus accumbens and olfactory tubercle did not differ between strains and was not affected by chronic binge cocaine. In the caudate putamen, subregion specific strain differences in dopamine D(1) receptor binding were observed; chronic binge cocaine increased dopamine D(1) receptor binding in the caudal (P<.05), but not rostral caudate putamen. There was no correlation between locomotor activity or stereotypy and dopamine D(1) receptor density. Thus, with chronic binge cocaine administration, behavioral differences persist between the C57BL/6J and 129/J mice, and cocaine-induced locomotor activity is not correlated with changes in dopamine D(1) receptor binding.

Animals↗

PubMed2002

Effects of acute "binge" cocaine on preprodynorphin, preproenkephalin, proopiomelanocortin, and corticotropin-releasing hormone receptor mRNA levels in the striatum and hypothalamic-pituitary-adrenal axis of mu-opioid receptor knockout mice.

Cocaine administration increases activity at dopamine receptors, increases preprodynorphin (ppDyn) gene expression in the caudate-putamen (CPu), and activates the stress responsive hypothalamic-pituitary-adrenal (HPA) axis. To examine the hypothesis that mu-opioid receptors (MOR) may play roles in these cocaine effects, we tested the effects of acute "binge" pattern cocaine administration in mice with targeted disruption of the MOR gene. Wild-type (+/+) and homozygous MOR-deficient (-/-) mice received three injections of 15 mg/kg cocaine at 1-h intervals. Mice were sacrificed 30 min after the last injection and mRNAs for ppDyn and preproenkephalin (ppEnk) in the CPu and nucleus accumbens (NAc), and for type I corticotropin-releasing hormone receptor (CRH(1) receptor) and pro-opiomelanocortin (POMC) in the hypothalamus and pituitary, were measured by solution hybridization RNase protection assays. Cocaine elevated ppDyn mRNA in the CPu, but not NAc, of both the MOR -/- and wild-type mice. ppEnk mRNA in the CPu, but not NAc, was lower in MOR -/- mice than in wild-type mice following cocaine administration. Hypothalamic CRH(1) receptor and POMC mRNAs were expressed at similar levels in untreated and in cocaine-treated mice of each genotype. However, there were lower basal levels of CRH(1) receptor mRNA in the anterior pituitary of the MOR -/- mice than in wild-type mice and the MOR -/- mice failed to show the cocaine-induced decreases in CRH(1) receptor mRNA found in the wild-type mice. Cocaine activated the HPA axis similarly in MOR -/- and wild-type mice, as reflected in similar increases in plasma corticosterone levels in both genotypes. These results support a specific role for MORs in acute cocaine effects on striatal ppEnk gene expression and fail to support critical roles for these receptors in acute cocaine's effects on either ppDyn gene expression or HPA activation. MOR -/- mice are useful models for studying cocaine effects on ppEnk gene expression that could aid interpretation of the similar postmortem phenomena found in human cocaine addicts.

Animals↗

PubMed2002

Potentially functional polymorphism in the promoter region of prodynorphin gene may be associated with protection against cocaine dependence or abuse.

It has been demonstrated that the opioid peptide dynorphin plays a role in modulating responses to several psychoactive substances including cocaine. Our laboratory and others have found that mRNA levels of dynorphin in the caudate and putamen are elevated after acute or chronic cocaine exposure in rats. Recently, a 68-base pair (bp) repeat polymorphism within the core promoter region of the human prodynorphin gene has been reported to occur in alleles containing one, two, three, or four copies. This repeat contains a putative AP-1 transcription factor binding site; reporter gene constructs with three or four, but not one or two, copies of the tandem repeats were shown to be associated with increases in transcriptional activation in in vitro cellular assays. We hypothesize that this polymorphism may be associated with individual differences in vulnerability to cocaine dependence or abuse. From an ongoing study of the genetics of addiction, 174 subjects were studied, including individuals with a primary diagnosis (DSM-IV criteria) of cocaine dependence (N = 61) or abuse (N = 22), and controls with no history of any substance dependence or abuse (N = 91). We designed primers for polymerase chain reaction (PCR) to amplify sequences of the promoter region of the prodynorphin gene containing the repeat element. The association of alleles containing three or four repeats with cocaine dependence/abuse was examined. With data stratified by ethnic group, pooled relative risk (RR) with Mantel-Haenszel Chi square was calculated: RR = 0.59 (95% confidence interval 0.37-0.95), chi2 (1) = 4.14, P = 0.042. Our results suggest that this allelic variation at the promoter region of the prodynorphin gene (alleles with three or four repeats), which may result in enhanced transcription of the gene, may contribute to relative protection and decrease individual vulnerability to develop cocaine dependence or abuse.

Alleles↗

PubMed2002

Conditioned place preference after single doses or "binge" cocaine in C57BL/6J and 129/J mice.

The rewarding effect of cocaine as reflected by the development of conditioned place preference was examined in C57BL/6J and 129/J mice. Cocaine was administered in a single daily dose (2.5, 5, 10 and 20 mg/kg ip) or in a "binge" pattern (15 mg/kg ip x3, hourly). Mice remained in the conditioning compartment for 30 min immediately after each injection. Single injections of cocaine from 5 to 20 mg/kg induced conditioned place preference in each strain of mice. Only C57BL/6J mice developed conditioned place preference after "binge" cocaine administration. Both strains showed significantly greater locomotion in the conditioning compartment across the range of single doses of cocaine and after "binge" cocaine administration, but only 129/J mice showed sensitization. When mice that had received the single 10 mg/kg dose were retested 4 weeks later, the amount of time spent in the preferred side was significantly reduced compared to the initial test in the 129/J, but not in C57BL/6J mice. Thus, the persistence of conditioned place preference is strain dependent. The fact that 129/J mice did not develop conditioned place preference after "binge" cocaine administration, but did after single doses, suggests that the rewarding effects of cocaine are influenced by pattern of administration, a factor that may be relevant to the development of human cocaine addiction.

Animals↗

PubMed2002

Hypothalamic-pituitary-adrenocortical (HPA) axis response and biotransformation of oral naltrexone: preliminary examination of relationship to family history of alcoholism.

We examined HPA axis response to 50 mg oral naltrexone compared with placebo in 17 healthy male and female nonalcoholic subjects, approximately half of whom had a positive family history of alcoholism (FH+) and half of whom who did not (FH-). Mood response and naltrexone biotransformation were also examined at various intervals. Subjects participated in two morning test sessions (50 mg naltrexone or identical placebo pill) after an overnight stay in the Rockefeller University GCRC. For the total sample, ACTH and cortisol significantly increased after naltrexone compared with placebo (p <.05). Secondary analyses showed the FH+ subgroup had a different pattern of response over time compared with the FH- subgroup, with heightened ACTH and cortisol, and decreased vigor ratings, during naltrexone (p <.05). The results demonstrate that orally administered naltrexone acutely disinhibits the HPA axis, and that individuals with an assumed greater biological vulnerability to addiction, by virtue of familial alcoholism, had altered regulation of the HPA axis in part under the control of the endogenous opioid system. 166 words.

Administration, Oral↗

PubMed2002

The Personality Assessment Inventory Drug Problems Scale: a validity analysis.

An analysis of the relationship among the Personality Assessment Inventory (PAI; Morey, 1991, 1996) Drug Problems (DRG) scale scores, the Addiction Severity Index (ASI; McLellan et al., 1992) scores, and urine toxicology reports revealed that the PAI Drug Problem scale scores of 100 substance-using and substance-abusing men and women were distributed in a manner that was in agreement with the guidelines suggested by Morey (1991, 1996) in the PAI manual. There were significant correlations among the PAI DRG scale and the ASI scales related to frequency of use, negative consequences of use, and need and desire for treatment. Overall, higher scores did reflect both more serious involvements with drug use and more serious problems as a consequence of their involvement.

Adult↗

PubMed2002

The use of levo-alpha-acetylmethadol (LAAM) in methadone patients who have not achieved heroin abstinence.

Levo-alpha-acetylmethadol (LAAM) pharmacotherapy was offered to twelve patients who continued illicit opioid abuse after > or = eleven months in methadone maintenance treatment. After 6-8 weeks on LAAM, plasma concentrations of the norLAAM metabolite varied significantly by LAAM dosing day, plasma adrenocorticotropin (ACTH) concentrations were significantly increased compared to methadone, and two of the seven subjects remaining in LAAM treatment were free of illicit opioids and nonprescribed methadone. After one year, one of five remaining subjects was using illicit opioids, and three were using non-prescribed methadone. While subject acceptance of LAAM was high, subjects were not in a "steady-state," with evidence of ongoing illicit opioid abuse.

Adrenocorticotropic Hormone↗

PubMed2002

Hepatitis C virus and human immunodeficiency virus-1 co-infection in former heroin addicts in methadone maintenance treatment.

OBJECTIVES: To investigate hepatitis C (HCV) and human immunodeficiency virus (HIV-1) prevalence in former opiate or heroin addicts currently in methadone maintenance treatment (MMT). METHODS: Retrospective chart review for patients (n = 342) currently attending two MMT clinics affiliated with New York Presbyterian Hospital (Adolescent Development Program, ADP: n = 106, median age 30 years; Adult Clinic, AC: n = 236, median age 45 years), as of May 2000. RESULTS: Overall seroprevalence of those tested was 67% for HCV (ADP, 44%; AC, 80%), and 29% for HIV-1 (ADP, 13%, AC, 39%). Co-infection was present in 26% of patients (ADP, 13%; AC, 35%). Prevalence of HCV reached 92% in the 45-49 year old group (n = 53). The greatest HIV-1 prevalence (45%) was in the 35-39 year old group (n = 33). There was a linear relationship between infection seroprevalence and age at admission into MMT. CONCLUSIONS: The high prevalence of HCV and HIV-1 infections in MMT patients varies both by current age and by age at admission to MMT. This population needs risk reduction education and treatment for HCV and HIV- 1.

Adult↗