Resistance to extrapyramidal effects of opiates in rats chronically treated with SCH 23390

Endogenous retroviruses drive species-specific germline transcriptomes in mammals

Gene regulation in the germline ensures the production of high-quality gametes, long-term maintenance of the species, and speciation. Male germline transcriptomes undergo dynamic changes after the mitosis-to-meiosis transition and have been subject to evolutionary divergence among mammals. However, the mechanisms underlying germline regulatory divergence remain undetermined. Here, we show that endogenous retroviruses (ERVs) influence species-specific germline transcriptomes. After the mitosis-to-meiosis transition in male mice, specific ERVs function as active enhancers to drive germline genes, including a mouse-specific gene set, and bear binding motifs for critical regulators of spermatogenesis such as A-MYB. This raises the possibility that a genome-wide transposition of ERVs rewired germline gene expression in a species-specific manner. Of note, independently evolved ERVs are associated with the expression of human-specific germline genes, demonstrating the prevalence of ERV-driven mechanisms in mammals. Together, we propose that ERVs fine-tune species-specific transcriptomes in the mammalian germline.

Selective interaction of homophtalazine derivatives with morphine

Homophtalazines show specific binding sites in the nigrostriatal system and to find their target of action the interactions between these derivatives, nerisopam and girisopam, and chlorpromazine, chlordiazepoxide and morphine were assessed. The compounds did not influence the chlorpromazine induced decrease in motility and catalepsy, nor did they alter the antiaggressive and anticonvulsive action of chlordiazepoxide. However, nerisopam and girisopam augmented the agonist potency of morphine to induce catalepsy or analgesia; they also altered the opioid antagonist potency of naloxone. The naloxone-induced decrease in sucrose consumption in drinking water was augmented by nerisopam and girisopam. It is suggested that a possible target of action of homophtalazines is the opioid signal transduction.

Effect of morphine-induced catalepsy, lethality, and analgesia by a benzodiazepine receptor agonist midazolam in the rat

Previously we have shown that intrathecal administration of midazolam can increase or decrease morphine-induced antinociception, depending upon relative concentration of these drugs by modulating spinal opioid receptors, and it also can inhibit morphine-induced tolerance and dependence in the rat. Now we report that midazolam also influences catalepsy, lethality, and analgesia induced by morphine in the rat. In the acute treatment, animals were first treated with saline or midazolam (0.03 to 30.0 mg/kg, b.wt., IP), and 30 min later with a second injection of saline or morphine (1.0 to 100.0 mg/kg, b.wt., SC). The catalepsy was measured 60 min after the second injection and lethality was checked after 24 h. Midazolam injection increased the morphine-induced catalepsy and lethality. In the chronic treatment, animals were injected with two injections daily for 11 days. The first injection consisted of saline or midazolam (0.03 to 3.0 mg/kg, b.wt., IP), and 30 min later with a second injection of saline or morphine (10.0 mg/kg, b.wt., IP) was given. Lethality, antinociception, and body weight were measured. Chronic morphine treatment also increased lethality in a dose-dependent manner. Chronic treatment with midazolam and morphine increased the antinociception on day 11, as measured in the tail-flick and hot-plate tests. Midazolam administration also prevented the morphine-induced weight loss. These results suggest a strong interaction between midazolam and morphine in altering catalepsy, lethality, and analgesia in rat.

Naloxone antagonizes ethanol- but not gamma-hydroxybutyrate-induced sleep in mice

The present study examined the effect of naloxone on ethanol- and gamma-hydroxybutyric acid-induced narcosis in mice and the changes induced by these drugs on striatal dopamine metabolism. The results show that naloxone (1-10 mg/kg s.c.) markedly reduced ethanol-induced narcosis but failed to modify the duration of sleep induced by gamma-hydroxybutyrate. Naloxone (10 mg/kg) modified neither ethanol- nor gamma-hydroxybutyrate-induced changes in striatal dopamine and dihydroxyphenylacetic acid (DOPAC) content. The results suggest that gamma-hydroxybutyrate- and ethanol-induced narcosis are mediated by different mechanisms and that opioid receptors are not involved in the changes in dopamine metabolism induced by these compounds.

Endogenous opiates: 1989

This paper is the twelfth installment of our annual review of the research published during 1989 involving the behavioral, nonanalgesic, effects of the endogenous opiate peptides. The specific topics this year include stress; tolerance and dependence; eating; drinking; gastrointestinal and renal functions; mental illness; learning, memory, and reward; cardiovascular responses; respiration and thermoregulation; seizures and other neurological disorders; electrical-related activity; locomotor activity; sex, development, pregnancy, and aging; immunological responses; and other behavior.