Monoaminergic drugs and directly observable signs of LAAM withdrawal in rhesus monkeys.

Monoaminergic ligands modified a naltrexone discriminative stimulus in rhesus monkeys dependent on 2 mg/kg per day of the mu opioid L-alpha-acetylmethadol (LAAM). This study examined a role for monoamines in the directly observable and physiologic manifestations of LAAM withdrawal induced by naltrexone in the same monkeys. The effects of saline, clonidine (0.032 mg/kg), haloperidol (0.032 mg/kg), cocaine (1.0 mg/kg), amphetamine (1.0 mg/kg) and imipramine (10.0 mg/kg) were examined in LAAM-dependent monkeys that subsequently received saline or naltrexone (0.0001-1.0 mg/kg). Naltrexone dose-dependently increased respiration, abdominal rigidity and salivation. Clonidine attenuated each of these withdrawal signs, whereas haloperidol increased some (i.e. respiration) and decreased others (i.e. salivation). When administered alone, cocaine and amphetamine increased respiration and also increased the respiratory stimulant effects of naltrexone; cocaine and amphetamine did not attenuate any measure of withdrawal. With the exception of a decrease in naltrexone-induced salivation, imipramine was without effect. These results are strikingly different from results in these same LAAM-dependent monkeys showing that cocaine and amphetamine, but not clonidine, markedly attenuated a naltrexone discriminative stimulus. That monoaminergic ligands differentially alter the directly observable and discriminative stimulus effects of naltrexone in LAAM-dependent monkeys supports the view that monoamines differentially mediate the physical manifestations (norepinephrine) and subjective experience (dopamine) of opioid withdrawal.

Influence of ovarian hormones and estrous cycle on the behavioral response to cocaine in female rats.

Both humans and experimental animals demonstrate gender differences in response to cocaine. However, the mechanisms underlying these differences remain unclear. The purpose of the present study was to determine whether ovarian steroid hormones play a role in the locomotor response to cocaine in rats. Initial assessments of locomotor activity measured using photobeam monitors verified the robust gender difference in response to cocaine in our experimental paradigm. Subsequently, cocaine (5.0, 7.5, and 10.0 mg/kg) was shown to increase total horizontal activity in a dose-dependent manner in independent groups of intact females; the 5.0 mg/kg dose was selected for use in additional studies to determine the effect of estrogen (E) and progesterone (P) on the response to cocaine. Mature female rats were ovariectomized (OVX) or OVX and implanted with hormone-filled (E or P) Silastic capsules. Three to 4 weeks later, automated and observational measures of behavior were recorded after the administration of 5 mg/kg cocaine. Hormone replacement with E or E + P (but not P alone) resulted in greater cocaine-evoked hyperactivity than was observed in OVX animals. On measurement in normally cycling rats, hyperactivity induced by 5 mg/kg cocaine was greater during proestrus and estrus than during diestrus 2. The results of this series of experiments demonstrate that E significantly influences the responsiveness of female rats to cocaine. The enhanced response to cocaine was demonstrated in the presence of pharmacologically administered E as well as correlated with the normal estrous cycle.

Perfusion deficit parallels exacerbation of cerebral ischemia/reperfusion injury in hyperglycemic rats.

Magnetic resonance imaging (MRI) techniques were used to determine the effect of preexisting hyperglycemia on the extent of cerebral ischemia/reperfusion injury and the level of cerebral perfusion. Middle cerebral artery occlusion (MCAO) was induced by a suture insertion technique. Forty one rats were divided into hyperglycemic and normoglycemic groups with either 4 hours of continuous MCAO or 2 hours of MCAO followed by 2 hours of reperfusion. Diffusion-weighted imaging (DWI) was performed at 4 hours after MCAO to quantify the degree of injury in 6 brain regions. Relative cerebral blood flow (CBF) and cerebral blood volume (CBV) were estimated using gradient echo (GE) bolus tracking and steady-state spin echo (SE) imaging techniques, respectively. Brain injury correlated with the perfusion level measured in both SE CBV and dynamic GE CBF images. In the temporary MCAO model, mean lesion size in DWI was 118% larger and hemispheric CBV was reduced by 37% in hyperglycemic compared with normoglycemic rats. Hyperglycemia did not significantly exacerbate brain injury or CBV deficit in permanent MCAO models. We conclude that preexisting hyperglycemia increases acute postischemic MRI-measurable brain cellular injury in proportion to an associated increased microvascular ischemia.

Inherited unbalanced subtelomeric translocation in a child with 8p- and Angelman syndromes.

A 10 1/2-month-old boy was found to have an unbalanced karyotype, 45,XY,der(8)t(8;15) (p23.3;q13). One of 83 analyzed cells also contained an unidentified small marker. Fluorescence in situ hybridization (FISH) using cosmid probes for SNRPN, D15S10, and GABRB3 for the Prader-Willi syndrome (PWS)/Angelman syndrome (AS) critical region were not present on the derived chromosome. The child had some physical findings compatible with monosomy 8p. The mother also was a balanced carrier for the translocation. She also had 2/80 cells with an additional small marker chromosome, similar in size to the extra chromosome in the one cell of the propositus. FISH using an 8 paint did not show the reciprocal exchange on the der(15) but was demonstrated by using an 8p telomeric probe. At 18 months of age the child has some manifestations of AS. Earlier diagnosis may have been masked by the 8p- phenotype, or related to difficulty in diagnosing AS in infants.

Cloning and expression of unique murine macrophage colony-stimulating factor transcripts.

Cocultivation of cells from the gamma-irradiated D2XRII murine bone marrow stromal cell line with an interleukin-3/granulocyte-macrophage colony-stimulating factor (GM-CSF)-dependent hematopoietic progenitor cell line FDC-P1JL26 stimulates the emergence of factor-independent hematopoietic cell sublines. Several lines of evidence suggested that M-CSF or a protein antigenically related to M-CSF, termed leukemogenic stromal factor (LSF), that was expressed by D2XRII cells may have played a role in the emergence of the factor-independent sublines. In an effort to isolate a factor antigenically related to M-CSF, molecular clones were isolated from a D2XRII cDNA library that hybridized to a mouse M-CSF genetic probe. Two of these molecular clones, designated 60.8.2 and 6452, contained an 885-bp deletion in the M-CSF coding region. Such a cDNA clone has not been previously described in the mouse, but a cDNA clone homologous to it has been isolated from a human pancreatic tumor cell line, MIA-PaCa-2. Three transcripts (4.8, 3.4, and 1.8 kb) were detected that hybridized to an oligonucleotide probe that was specific to RNA transcripts containing the 60.8.2 deletion. The level of the 1.8-kb transcript was not detectably induced by ionizing irradiation; however, the levels of the 4.8-kb and 3.4-kb transcripts and two other M-CSF transcripts of sizes to 4.4 kb and 2.3 kb showed a 1.4- to 2.2-fold increase after gamma irradiation. Reverse transcription-polymerase chain reaction showed that the deletion-specific transcript(s) was detected in multiple mouse bone marrow stromal cell lines and in normal mouse tissues. The present studies establish the existence of an increased spectrum of murine M-CSF transcripts in bone marrow stromal cells and other tissues. This complexity of transcripts along with their increased accumulation after irradiation provides additional evidence for a role of proteins encoded by M-CSF transcripts in the response of bone marrow stromal cells to ionizing irradiation.

Cold-induced increases in phenylethanolamine N-methyltransferase (PNMT) mRNA are mediated by non-cholinergic mechanisms in the rat adrenal gland.

Previously, we reported that cold stress induces a rapid increase in adrenomedullary PNMT mRNA levels, followed by concomitant increases in PNMT immunoreactivity (10). In the present study, the extracellular signals mediating this adaptive response to stress were investigated using northern analysis and RNA slot-blot hybridization. Although adrenal denervation significantly diminished cold-induced increments in adrenomedullary PNMT mRNA levels, it did not completely abolish the cold stress response. In contrast to these results, splanchnectomy completely inhibited cold-induced increments in TH mRNAs in the same tissue samples. These findings indicate that the effects of cold exposure on PNMT mRNA levels are mediated by both neural and non-neural mechanisms, and that adrenal PNMT and TH are differentially regulated in response to cold stress. Surprisingly, the neural component of the PNMT stress response could not be attenuated by peripheral administration of chlorisondamine, a powerful nicotinic ganglionic blocking agent. In contrast, chlorisondamine was effective in inhibiting sympathetic neural activity, as judged by the drug's ability to completely block increases in blood pressure, heart rate, and plasma catecholamines resulting from spinal cord stimulation in pithed rats. The administration of atropine, a muscarinic receptor antagonist, also failed to inhibit cold-induced alterations in adrenal PNMT mRNA. These results suggest that the trans-synaptic induction of adrenal PNMT mRNA involves a non-cholinergic component, and that cold-induced increases in PNMT mRNA are not coupled to acetylcholine-mediated adrenal catecholamine release.

Cold-induced alterations in the binding of adrenomedullary nuclear proteins to the promoter region of the tyrosine hydroxylase gene.

It is well documented that cold stress induces a rapid trans-synaptically mediated increase in the relative abundance of rat adrenomedullary tyrosine hydroxylase (TH) mRNA. To investigate the transcriptional mechanisms regulating the cold stress response, we have employed a gel mobility shift assay, using DNA fragments prepared from the proximal 5' flanking region of the bovine TH gene as a heterologous molecular probe. In pilot studies, this region of the bovine TH promoter (nucleotides -246 to +21) was fused to the bacterial reporter gene, chloramphenicol acetyltransferase, and the chimeric construct transfected into human neuroblastoma SK-N-BE(2)-C, hepatoma HepG2, and rat pheochromocytoma PC-12 cells. Results of this analysis indicate that the proximal 5' flanking region of the bovine TH gene contains sufficient information to drive transient reporter gene expression in both human and rat catecholaminergic clonal cell lines. The findings derived from the gel mobility shift studies demonstrate that cold exposure causes rapid and selective alterations in the binding of adrenomedullary nuclear proteins to the proximal 5' flanking region of the TH gene. The most striking cold stress-induced alteration in DNA/nucleoprotein binding occurs in a region of the TH promoter (nucleotides -246 to -189) which contains an element bearing marked sequence similarity to an AP1 binding site and is highly conserved among animal species. This alteration occurs within 1 hr of cold exposure and persists for up to 48 hr after the onset of stress. The results of adrenal denervation experiments indicate that the cold-induced change in DNA/nucleoprotein binding is neurally mediated, requiring intact sympathetic innervation of the gland.(ABSTRACT TRUNCATED AT 250 WORDS)