interaction between temperature humidity index and some health parameters of sheep under the Egyptian oasis environment [with 9 tables and 3 figures]

Darb Al-Arbain is a virgin area and represents the southern boundary of the Egyptian oasis depression. It considers one of the most promising areas for agricultural expansion in Egypt. This study aimed to setup a preliminary data on some health indices including clinical, haematological, hormonal and metabolic picture in desert [Barki] and Nile valley [Rahmani and Ossimi] sheep 'which were recently transported with their owners to this newly reclaimed area. Also, to correlate between these indices and the temperature humidity index [THI] as a trial to evaluate the effect of heat stress on the health indices of these sheep. To nullify the effect of age throughout the study period [6 months], this work was designed to select 3 groups of male lambs [15 each; average 7 months and around 24 kg]. Each group represented two months of the study period, so that the three groups represented a cycle of 6 consecutive months began by February [basal data] to July [intensified dry summer stress]. Each group included three subgroups of Rahmani, Ossimi and Barki lambs [5/breed]. Clinical, haematological and biochemical investigations were carried out monthly throughout 6 months study period. The average of maximum ambient temperatures at the end of July was 154.7% higher and the relative humidity was116.8 lower than the basal thermoneutral data. The effect of breed under the changes of THI was significant for rectal temperature, respiratory rate, PCV, potassium and cortisol. The patterns of estimated parameters were insignificantly fluctuated in Barki and Ossimi sheep except the significant elevation of rectal temperature and respiratory rate [at THI above 90]. In Rahmani sheep, the magnitude of rectal temperature and respiratory rate [at THI 85 and 88 respectively] preceded those in other breeds. On the other hand the values of RBC, Hb, PCV, plasma total protein, albumin, K, T[3] were decreased and Na and cortisol values were increased in Rahmani sheep when THI reached 92. Correlation coefficient showed that respiration rate was highly correlated with increasing THI [r=0.738, P=0.0005], whereas rectal temperature was less responsive to THI [r = 0.561, P=0.015]. It was noticed also that THI was negatively correlated with RBC, PCV, total protein, albumin, potassium, T[3], T[4] and positively correlated with Na. The hot arid and drought desert environment did not affect health indices in Barki and Ossimi sheep inhabiting Darb Al-Arbain area. The measured values were within the normal physiological ranges reported for sheep. In despite, the changes in clinical and biochemical indices showed that health of Rahmani breed was at risk only when THI was above 85 and not at 81 as reported for temperate breeds. From these results, this study recommends to establish suitable new THI categories for native breeds reared under tropical environment

Influence of melatonin and serotonin on some parameters of respiratory activity in rabbits

This study showed the effect of intravenous [iv] injection of melatonin in doses of 0.1, 0.5 and 1.0 mg/kg and serotonin in doses of 0.1, 0.3 and 0.5 mg/kg on the rate and depth of respiration in adult male rabbits. Intravenous injection of melatonin [1 mg/kg] caused a decrease in the frequency and an increase in the depth of respiration which resulted in a fall in PaCO2 and SaO2. Hypoventilation led also to an increase in PaCO2. The effect of melatonin on the rate and depth of respiration started immediately post-injection of melatonin and the maximum effect was recorded after 5 minutes and returned to the normal levels within 10 minutes of injection. Based on the results it can be concluded that melatonin as well as serotonin may have an important effect on the regulation of ventilation. Melatonin may affect respiration by acting directly on the muscle of respiration, while serotonin effect may be due to its direct action on chemoreceptors

Effect of midazolam and diazepam on either spontaneous or oxytocin induced contractions of isolated pregnant mouse uterus near term

Midazolam is a water soluble member of the benzodiazepine group of drugs which were thoroughly investigated as sedative hypnotics and anticonvulsant drugs. However its effect on the uterus was not yet sufficiently explored. Therefore the present study was carried on to investigate the effect of midazolam and diazepam on the isolated uterus of pregnant mouse near term. Doth midazolam and diazepam were added to the organ bath either alone or after oxytocin. The effects of these drugs on the uterus were recorded and compared with the effect of magnesium sulfate as a tocolytic agent. Diazepam produced significant decrease in the spontaneous uterine activities. Neither midazolam nor diazepam could produce any effect on the oxytocin induced uterine contractions compared to magnesium sulfate which could inhibit both spontaneous as well as oxytocin induced uterine activities. It was concluded that midazolam and diazepam can be used therapeuticaly as an alternative for magnesium sulfate to control eclamptic fits without interference with the effect of oxytocin if it is indicated to induce labour

Effect of melatonin on baroreflex control of heart rate in rabbits

The effect of intravenous injection of melatonin [0.1 mg/kg, 0.5 mg/Kg and 1 mg/Kg] on arterial blood pressure and heart rate in adult male rabbits was investigated in this study. Baroreflex function was assessed using phenylephrine [the pressor test] to induce moderate changes in arterial blood pressure and to alter the stimulation of baroreceptor sites. In addition, the effect of melatonin on sympathetic and parasympathetic efferent nerve activity was also investigated. Melatonin resulted in a lowering effect on arterial blood -pressure with a decrease in heart rate. The significant decrease of arterial blood pressure was observed at a dose as low as 0.5 mg/Kg. The lowering effect of melatonin on heart rate was detected at 1 mg/Kg. Baroreflex slope was not depressed significantly with a significant increase in pulse interval, until I mg/Kg melatonin. Sympathetic and vagal nerve activities were attenuated significantly by melatonin. This study indicated that baroreflex control of heart rate was depressed by intravenous administration of melatonin. There was a dissociation between the effect of melatonin on baroreflex sensitivity versus the effect of low blood pressure. Melatonin was found to alter the baroreflex heart rate response through its direct depressant effect on baroreceptors and on both sympathetic and parasympathetic efferent nerve pathways