Effects of cytidine-diphosphocholine on acetylcholine-mediated behaviors in the rat.

The phosphatidylcholine precursor, cytidine-diphosphocholine (CDP-choline), was injected intraperitoneally (IP) at the dose of 10 or 20 mg/kg/day for 20 days to 24-month-old male rats of the Sprague-Dawley strain that showed cognitive and motor deficits. The drug was also injected in animals with behavioral alterations induced pharmacologically with a single injection of the cholinergic receptor antagonist, scopolamine, with prenatal exposure to methylazoxymethanol (MAM rats), or with bilateral injections of kainic acid into the nucleus basalis magnocellularis (NBM). Learning and memory capacity of the animals, studied with tests of active and passive avoidance behavior, was improved after treatment with CDP-choline in all experimental groups. An improvement in motor performance and coordination in the rotorod and open field tests was also observed in aged rats. These results indicate that this drug affects central mechanisms involved in cognitive behaviors, probably through a cholinergic action.

[Cerebral actions of dihydroergocristine]. / Zerebrale Wirkungen von Dihydroergocristin.

Dihydroergocristine (DEC, CAS 17479-19-5) is a dihydrogenated ergot alkaloid with a potent dopaminergic activity that has been proved both in vitro and in vivo. Apart from its effect on the secretion of pituitary hormones, the following actions have been evidenced. It induces stereotyped behaviour and changes in the sleep-waking cycle, and reduces hypoxia-induced cerebral metabolic changes and emesis. The effect of DHEC on behaviour patterns has been studied in aged male rats in comparison with young animals. The acquisition of the active avoidance response in the shuttle-box test and the retention of the passive avoidance response in a step-through passive avoidance task were facilitated in aged rats by an acute treatment with DHEC. The effect on the acquisition and extinction of the pole-jumping performance after a single injection of DHEC at the beginning of the acquisition session was restricted to the first acquisition trial. A more potent effect on the acquisition of the shuttle-box response and on the retention of passive avoidance reaction was found in animals treated subchronically with DHEC. The latter animals also showed a facilitation of acquisition and an inhibition of extinction of the pole-jumping performance. In other experiments, the repeated administration of DHEC was followed by a decrease in the excessive grooming in aged rats, which is considered a sign of the lack of adaptability of these animals. A facilitation of the compensatory mechanisms in experimental models of vertigo has also been found in animals treated with DHEC.

Effects of thyrotropin-releasing hormone, oxytocin, and prolactin on thiopenthal-induced narcosis in rats.

Neuropeptides that may induce behavioral activation--thyrotropin-releasing hormone (TRH), oxytocin (OXY), and prolactin (PRL)--were tested on thiopenthal-induced narcosis after IV administration in male rats. TRH caused a significant shortening of sleeping time at the doses of 3 and 5 mg/kg, but did not change this parameter at lower doses. Oxytocin was effective at all doses tested (200, 300, and 400 micrograms/kg). Prolactin also shortened sleeping time at the doses of 0.2 and 1 mg/kg administered IV, slightly increasing it at the dose of 5 mg/kg. These results indicate that various neuropeptides are capable of reducing the duration of thiopenthal-induced sleep in rats.

Behavioral effects of L-alpha-glycerylphosphorylcholine: influence on cognitive mechanisms in the rat.

The phosphorylcholine precursor, L-alpha-glycerylphosphorylcholine (alpha-GPC), was injected at the dose of 100 mg/kg/day for 20 days to aged male rats of the Sprague-Dawley strain, 24 months old, showing a deficit of learning and memory capacity. The drug was also administered to rats with amnesia induced pharmacologically with bilateral injections of kainic acid into the nucleus basalis magnocellularis (NBM). Learning and memory capacity of the animals, studied with tests of active and passive avoidance behavior, was improved after treatment with alpha-GPC in all experimental groups. These results indicate that this drug affects cognitive mechanisms in the rat through an involvement of central neurotransmission.

Protective action of phosphatidylserine on stress-induced behavioral and autonomic changes in aged rats.

Phosphatidylserine (PS) was administered in aged rats subjected to various stressor stimuli in order to evaluate its effect on grooming behavior, core temperature and gastric ulcers. Novelty-induced grooming appeared to be increased in aged rats as compared to young controls. The subchronic intraperitoneal treatment with PS (20 mg/kg/day for 20 days) decreased grooming activity in aged rats, whereas it did not affect that of young animals. Restraint stress induced hyperthermia in both aged and young rats. However, 90 min after the beginning of restraint, PS-treated old rats showed a normalization of core temperature. Furthermore, restraint-plus-cold stress induced gastric ulcers in both aged and young rats. The treatment with PS was followed by a decreased incidence of gastric lesions in aged, but not in young rats. The mechanism of PS protective action against stress-induced behavioral and autonomic changes is unknown, but it may involve the brain level as this drug exerts a noteworthy influence on behavior and autonomic functions.