Latest research on Morphine

The principal alkaloid in opium and the prototype opiate analgesic and narcotic. Morphine has widespread effects in the central nervous system and on smooth muscle. [PubChem]

Latest findings

75 mg Morphine alkaloid pellets and placebo pellets were obtained from the National Institute on Drug Abuse (Bethesda, MD). [source, 2016]
We have studied the effects of Morphine on mice breathing 5% CO2 in air. [source, 2016]
Administration of Morphine (3–30 mg/kg i.p.) produced significant dose-dependent depression of respiration, which developed rapidly within 5 min of drug injection, and was maintained for the remainder (30 min) of the observation period (Figure 1a–c). [source, 2016]
As the experiments were performed in 5% CO2 in air, it is not possible to tell if the decrease in minute volume induced by Morphine is due to an action on respiratory rate generation or on chemoreflexes. [source, 2016]
As can be seen in Figure 1c, all mice tested responded to Morphine with a decrease in respiration, we did not observe any Morphine-insensitive animals. [source, 2016]
Morphine is known to induce locomotor activity in mice (Lessov and Phillips, 2003; Valjent ) and as this would likely increase respiration, it could mask the respiratory depressant actions of the drug, especially at high doses. [source, 2016]
Therefore, in a separate series of experiments, we measured locomotor activity for 30 min after Morphine (10–30 mg/kg) injection (Figure 1f). [source, 2016]
Only at 30 mg/kg did Morphine increase locomotor activity. [source, 2016]
For this reason, we have chosen in our subsequent experiments to use a dose of 10 mg/kg Morphine as the challenge dose, as the results would not be confounded by any change in locomotor activity. [source, 2016]
One possibility that we wished to exclude was that having the animals breathing 5% CO2 in air might induce stress and that the depression of respiration was due to an antianxiety effect of Morphine, not a direct effect on respiration. [source, 2016]