Linkage of plasminogen (PLG) and apolipoprotein(a) (LPA) in baboons.

Four allelic forms of serum plasminogen (PLG) were detected in baboons (Papio hamadryas Linneaus 1758) by isoelectric focusing and were determined to be inherited as autosomal codominant traits. Linkage analysis of data from 179 progeny and their parents revealed that PLG is tightly linked (lod score = 30.20) to the gene encoding apolipoprotein(a) (LPA), as in humans. No recombinant individuals were identified. This is the first linkage detected between PLG and LPA in any species other than humans and is the first genetic linkage identified in a nonhuman primate species by family studies.     

Rat brain proteome in morphine dependence

The aim of this study was to reveal potential markers associated with drug dependence, using the proteomic approach. Gels containing samples derived from morphine-treated and control animals were compared and analyzed. Inspection of protein profiles, following TCA/acetone precipitation and the use of nano-scale liquid chromatography coupled to tandem mass spectrometry, allowed for identification of eleven potential dependence markers, mainly cytoplasmic and mitochondrial enzymes, e.g. proteins that belong to GTPase and GST superfamilies, ATPase, asparaginase or proteasome subunit p27 families.     

Pharmacological manipulation of gamma-aminobutyric acid (GABA) in morphine analgesia,tolerance and physical dependence

The findings from our laboratory indicated that pharmacological manipulations of GABA system modified morphine analgesia, tolerance and physical dependence. Elevating brain levels of GABA by slowing its destruction with aminooxyacetic acid not only antagonized the analgesic action of morphine in both non-tolerant and tolerant mice, but also enhanced the development of tolerance and physical dependence. On the other hand, blockade of postsynaptic sites of GABA receptors by bicuculline resulted in an inhibition of tolerance and dependence development. Administration of 2,4-diaminobutyric acid, an inhibitor of GABA uptake in the neurons, antagonized morphine analgesia in both non-tolerant and tolerant mice. However, it did not modify naloxone precipitated withdrawal jumping. On the contrary, β-alanine, an inhibitor of the GABA uptake process in glial cells, potentiated naloxone precipitated withdrawal jumping in morphine dependent mice, but it had no effect on morphine antinociception in both non-tolerant and tolerant mice.     

Linkage between the loci for the Lp(a) lipoprotein (LP) and plasminogen (PLG)

Summary A locus, LP, that determines quantitative variation of Lp(a) lipoprotein phenotypes is linked to the plasminogen (PLG) locus (peak lod score =12.73). This linkage relationship assigns a locus with alleles that have an affect on risk for coronary artery disease to the long arm of chromosome 6.     

Inhibition of morphine dependence by a lipopolysaccharide from Pantoea agglomerans.

A lipopolysaccharide from Pantoea agglomerans (LPSp) was purified and examined for relief of morphine dependence by observing its inhibition of the jumping of mice on naloxone-precipitate withdrawal. Administration of LPSp either intravenously or intradermally showed marked inhibition of the jumping. Beta-endorphin in mouse serum and brain tissue were recognized to be in synchrony with the time course of the relief. Administration of TNF-alpha gave similar effect, suggesting that LPSp induces a cytokine cascade to produce endogenous TNF followed by ACTH/beta-LPH gene products and beta-endorphin. The effect of LPSp was better than that of LPS from E. coli or Bordetella pertussis, and thus is considered to be applicable for clinical use.     

Physical dependence in rats after low morphine doses

The minimum level of morphine administration necessary to produce physical dependence in rats was investigated. Rats received low doses of morphine (10 mg/kg) intraperitoneally once daily for 1, 3, or 5 days. Naloxone given intraperitoneally 1 hr. after the last morphine injection produced significant withdrawal signs after only three days.     

Antagonism of morphine tolerance and dependence by metoclopramide

Metoclopramide produced significant analgesic activity when tested by acetic acid induced writhing assay. Repeated injections of metoclopramide did not result in the development of tolerance to its analgesic activity. Pretreatment with metoclopramide antagonised acute morphine tolerance and suppressed the withdrawal signs (both in acute dependence type and abrupt withdrawal type). It is suggested that metoclopramide may be a useful tool in the management of morphine dependence.     

Attenuation of morphine tolerance and dependence by alpha-melanocyte stimulating hormone(alpha-MSH).

Repeated administration of morphine resulted in significant reduction of its analgesic potency. If 0.1 mg/kg α-MSH was coadministered, the tolerance development was attenuated, 1 mg/kg MIF (MSH release inhibiting factor), given simultaneously with morphine, did not affect tolerance. Injecting, however, MIF 1 hour prior to the daily opiate treatment resulted in accelerated development of tolerance supposedly by lowering the plasma α-MSH level at the time of morphine administration. Of the morphine abstinence symptoms the naloxone-induced jumping in morphine pretreated mice could not be modified either by α-MSH coadministration or by MIF pretreament, but the withdrawal body weight loss was found to be diminished by the former and increased by the latter peptide. The possible role of α-MSH in preventing the development of tolerance to the analgesic effect of endogenous opioid peptides is discussed.     

Rapid analysis of gene expression (RAGE) facilitates universal expression profiling.

Current techniques for analysis of gene expression either monitor one gene at a time, for example northern hybridization or RT-PCR methods, or are designed for the simultaneous analysis of thousands of genes, for example microarray hybridization or serial analysis of gene expression. To provide a flexible, intermediate scale alternative, a PCR-based method for the rapid analysis of gene expression has been developed which allows expression changes to be determined in either a directed search of known genes, or an undirected survey of unknown genes. A single set of reagents and reaction conditions allows analyses of most genes in any eukaryote. The method is useful for assaying on the order of tens to hundreds of genes in multiple samples. Control experiments indicate reliable detection of changes in gene expression 2-fold and greater, and sensitivity of detection better than 1 in 10 000. Analyses of over 400 genes in a mouse system transgenic for the E2F1 gene have identified several new downstream targets of E2F1, including Brca1 and Cdk7, in addition to several unidentified genes that are upregulated in the transgenic mice. Changes in expression of several genes related to apoptosis suggest a possible potentiation of apoptotic pathways in the transgenic keratinocytes.     

In-vitro evaluation of morphine dependence. III. Response of the rat ileum to ACh

The kinetic of cholinergic receptor systems was studied in an in vitro model for opiate tolerance and dependence. The isolated ileum of rate chronically treated with morphine and sacrificed at different time intervals and in different conditions (with and without abstinence signs) was used. In evaluating the response of this preparation to doses of ACh ranging from 5.5 x 10(-10) to 5.5 x 10(-7), no statistically significant response was found to the cholinergic receptor system in conditions of abstinence and non-abstinence in vivo and in vitro. On the other hand, statistically significant differences are related to duration of treatment in vivo. The pattern for these responses is similar to the one observed in the fundus (Note I) and it can be considered as an expression of morphine-induced tolerance.     

An opiate cocktail that reduces morphine tolerance and dependence

Morphine is an exceptionally effective analgesic whose utility is compromised by the development of tolerance and dependence to the drug. Morphine analgesia and dependence are mediated by its activity at the mu opioid peptide (MOP) receptor [1]. The MOP receptor is activated not only by morphine, but also by other opiate drugs such as methadone and endogenous opioids such as endorphins. Morphine, however, is a unique opioid agonist ligand because it fails to induce endocytic trafficking of the MOP receptor [2], whereas the endogenous ligands and methadone do facilitate endocytosis [3]. Using the unique pharmacology of the MOP receptor and its proposed existence as an oligomeric structure [4], we designed a pharmacological cocktail that facilitates endocytosis of the MOP receptor in response to morphine. This cocktail consists of morphine and a small dose of methadone. Importantly, this cocktail, while retaining full analgesic potency, does not promote morphine dependence. We further demonstrate that dependence is reduced, at least in part, because endocytosis of the MOP receptor in response to morphine prevents the upregulation of N-methyl-D-aspartate (NMDA) receptors.     

Possible role of cyclic AMP and dopamine in morphine tolerance and physical dependence.

In chronically morphinized rats undergoing naloxone induced withdrawal the cerebellar Cyclic 3′, 5′ adenosine monophosphate (Cyclic AMP) was significantly higher than the controls. The cerebellar dopamine (DA) and norepinephrine (NE) were decreased, elevated or unchanged depending on the duration of morphine treatment. The corpus striatal DA levels during withdrawal were markedly elevated and the striatal cyclic AMP levels were unchanged. The NE levels in the striatal tissue were either elevated or unchanged depending upon the duration of morphine administration. In sharp contrast to the chronically morphinized rats undergoing naloxone induced withdrawal, the rats made morphine dependent over a period of eight weeks showed quite moderate changes in the striatal and cerebellar cyclic AMP and DA levels. Thus alterations in the DA and the cyclic AMP levels in the central nervous system (CNS) may play an important role in the naloxone induced stereotyped morphine withdrawal behavior.     

In-vitro evaluation of morphine dependence. II. Response of the fat fundus to 5-HT

The kinetic of serotoninergic receptor systems was studied in an in vitro model for opiate tolerance and dependence. The fundus strip of rats chronically treated with morphine and sacrificed at different time intervals and in different conditions (with and without abstinence signs) was used. The differences between the response to the 5-HT in a situation of abstinence as compared to the same preparation in a situation of non-abstinence (in vitro model for dependence) are not statistically significant. The variations in the response as related to duration of treatment in vivo of the various groups of animals, cannot be significantly correlated to morphine-induced tolerance.     

Effect of cyclic nucleotides and phosphodiesterase inhibition on morphine tolerance and physical dependence.

The effects of cyclic nucleotides and theophylline were assessed in mice rendered tolerant to and physically dependent on morphine by the pellet implantation procedure. Tolerance was quantified by the increase in amount of morphine to produce analgesia and dependence by the decrease in amount of naloxone to precipitate withdrawal jumping. By these criteria, pretreatment with a single intravenous injection of cyclic 3′, 5′-adenosine monophosphate (cAMP) was found to enhance markedly tolerance and dependence development. Repeated injections of theophylline were also affective. Cycloheximide and beta-adrenergic blockers prevented the accelerating effect of cAMP and with more frequent administration also decreased the development of tolerance and dependence. It is concluded that cAMP may have a role in morphine tolerance and dependence development.     

In-vitro evaluation of morphine dependence. I. Response of the rat fundus to ACh]

The kinetic of cholinergic receptor systems was studied in an in vitro model for opiate tolerance and dependence. The fundus strip of rats chronically treated with morphine and sacrificed at different time intervals and in different conditions (with and without abstinence signs) was used. In evaluating the responses of fundus to ACh, the cholinergic receptor system showed the same response both in a condition of abstinence and in a condition of non-abstinence in vivo and in vitro. The response does vary however, according to the duration of the treatment: after an initial increase it comes back to its normal values, thus reproducing the tolerance pattern.