Otas E. Ukponmwan

Neuropeptide-Y Y2-receptor agonist, PYY3-36 promotes non-rapid eye movement sleep in rat

PYY3-36 is a major component of the gut-brain axis and peripheral administration has been reported to exert significant effects on feeding, brain function and is more selective for neuropeptide Y2 receptor. Therefore, we investigated the effects of nocturnal intraperitoneal administration of single doses of PYY3-36 (30 and 100 microg/kg i.p.) on food intake, water intake and the sleep-wake cycle in rats. Sleep recordings were carried out in male Sprague-Dawley rats implanted with cortical electroencephalogram (EEG) and neck electromyogram (EMG) electrodes. The EEG, EMG, food intake and water intake were assessed. The electrographic recordings obtained were scored visually as rapid eye movement (REM) sleep, non-REM (NREM) sleep and wakefulness. PYY3-36 administration 15 min prior to dark onset significantly (p<0.05) increased non-rapid eye movement (NREM) sleep and decreased wakefulness. Analysis of the dark-period at 4-h time intervals showed that nocturnal administration of PYY3-36 (30 and 100 microg/kg) significantly suppressed wakefulness and increased non-REM sleep during the first 4-h time interval. Time spent in wakefulness was significantly decreased after administration of PYY3-36 (30 and 100 microg/kg) when compared with administration of vehicle. In addition, PYY3-36 (30 and 100 microg/kg i.p.) induced an increase in the time spent in NREM sleep. The nocturnal intraperitoneal administration of the lower dose of PYY3-36 (30 microg/kg) also significantly decreased food intake [F (2,23)=4.90, p<0.05] but had no effect on water intake. These findings suggest that PYY3-36 may play an important role in the enhancement of NREM sleep and feeding behavior.

Acute and Sub-Chronic toxicity potential effects of Alchornea Cordifolia (Euphorbiaceae) in rats

Alchornea cordifolia (Euphorbiaceae) is a plant that has been shown to have considerable activity against a broad spectrum of bacteria including those that have developed resistance to several antibiotics. In view of the high prevalence of antibiotic resistant bacteria, the search for new effective antimicrobial substances is urgent and must be extended to higher plants such as A. cordifolia . A useful antimicrobial substance must however have a defined toxicity profile which is why this attempt was thought to be worthy of serious consideration. Both oral acute and sub-chronic toxicity studies were carried out in rats. Acute toxicity study revealed that the ethanolic extract has no significant effect on both Packed cell volume (PCV) and Hemoglobin (Hb) and biochemical parameters. Similarly, the sub-chronic administration had no significant effect on hematological parameters and biochemical parameters such as protein, total cholesterol, aspartate aminotransferase (AST), alanine aminotransferase (ALT), and glutathione (GSH), however, triglyceride (TG) and lactate dehydrogenase (LDH) were significantly increased at the dose of 250 mg/kg/day when compared with the vehicle-treated rats. Furthermore, there was a significant increase in protein, TG and LDH at the dose of 500 mg/kg/day when compared with the dose of 250 mg/kg/day. Histopathological results revealed that there were no significant changes in the organs of the treated animals when compared with vehicle-treated group. The open field test showed that sub-chronic administration increased rearing behavior significantly at the dose of 250 mg/kg/28 days but had no effect on grooming. In conclusion, the ethanolic extract has no toxicological effect as observed on hematological, biochemical and histopathological parameters even at the maximum dose administered suggesting that the plant ethanolic leaf extract is devoid of any toxicity effects.