[ effect of silymarin on learning and histological changes of hippocampal regions of rats]

Silymarin, an extract from seeds of milk thistle [Silybum marianum], is known to have hepato-protective, anticarcinogenic, antioxidant and estrogenic effects. The aim of the present study was to test the effect of silymarin on passive avoidance learning in rats. This was an experimental study carried on Wistar rats in Arak Unviersity, Iran. The animals were provided with silymarin [from day 7 of gestational age to 4 weeks after birth] at 2 doses of 180 mg/kg in the experimental group 1 [Exp 1] and 90mg/kg in the experimental group 2 [Exp 2] while the sham group received saline and the control group with regular food and water. The memory retention and duration of step-through latency in male offsprings was determined by passive avoidance apparatus. Neuronal density in hippocampus was established by histopathological value less than 0.05 was considered as significant. Both experimental groups showed significantly longer step-through latency compared to control group [p<0.05]. The average number of pyramidal cells in hippocampal CA1 and granular cells in the hippocampal DG were remarkably higher in Exp 1 and Exp 2 groups compared to control group. The difference between Exp 1 and Exp2 for pyramidal cells was found to be significant [p<0.01 and p<0.05, respectively]. Silymarin produced a significant increase in learning and memory. Also, our results indicate that silymarin is a dose dependent component. These data may lay a background for application of silybin in treatment of memory impairment diseases

[Effect of tamoxifen on reproduction capability of male wistar rats]

Tamoxifen is a nonsteroidal antiestrogen agent which is prescribed for treatment of breast cancer. The aim of this study is to investigate the effect of tamoxifen on testosterone concentration and structure of testis in male Wistar rats. In this experimental study One group of rats [45 days old and 90g body weight] received 800 micro g/kg b.w tamoxifen dissolved in solvent [consisted of ethanol [60%] and physiological solution] for 10 consecutive days. The sham group received the solvent and controls did not receive any drug or solvent. After treatment period, serum testosterone level of rats was measured by ELISA method and 5 micro m thickness tissue sections from testes were stained with Haematoxylin and Eosin. Results showed that testosterone concentration decreased significantly in group which received tamoxifen compared with control group [p<0.01]. A significant decrease was observed in testis diameter, thickness of seminiferous tubules and the number of spermatid and sperm cells [p<0.001]. According to these results, we concluded that the reproduction capability of adult male Wistar rats decreased significantly in animals which received tamoxifen in prepubertal stage

Interaction of alpha[2]-adrenergic system and caffeine on passive avoidance learning in male Wistar rats

There are numerous studies on the effects of caffeine on memory and learning. The activation of alpha[2]-adrenoreceptors has been reported to impair memory functions in both rats and humans. In this study, interaction of alpha[2]-adrenergic system and caffeine on memory and learning was evaluated. In this experimental study, 90 wistar rats assigned into six groups of fifteen. Rats received yohimbine [4, 6, 8, 10 micro g]. The cannula was implanted into the right lateral ventricle of all rats with steriotaxi method. Then, they were trained in shuttlebox. Post-training intracerebroventricular [ICV] injection was carried out in all experiments and optimum doses were identified. Caffeine and yohimbine fostered memory and learning [p<0.001], while clonidine diminished these abilities compared to saline injection [p<0.05]. Co-administration of the optimum doses of clonidine and yohimbine showed statistically significant reduction in the time of step-through latency [p<0.05]. Instead, co-administration of clonidine and caffeine revealed no significant increase in the time of step-through latency [NS]. It is concluded that yohimbine and caffeine, unlike clonidine, increase memory

Effect of tamoxifen on histological structure of testis in adult male wistar rats

Effect of tamoxifen on histological structure of testis in adult male Wistar rats Oryan S1, Parivar K1, Asle rousta M2 1 Professor, Department of Biology, Islamic Azad University, Science and Research Campus, Tehran, Iran. 2 Student of MSc of Physiology, Islamic Azad University, Science and Research Campus, Tehran, Iran. Tamoxifen is a non-steroidal anti-estrogen which is prescribed for treatment of breast cancer. The aim of this study was to investigate the effect of tamoxifen on of testes in adult male Wistar rats. This study was an experimental survey. Three groups of adult male Wistar rats received 200, 400 and 600 micro g/kg bw tamoxifen dissolved in a solvent [consisted of ethanol [60%] and physiologic solution] for 30 consecutive days. The sham group received the solvent and controls did not receive any drug or solvent. At the end of this period, the animals were sacrificed and their testes were removed and fixed in Bouin's fluid. Sections of 5 micro m thickness from testes stained with Haematoxylin and Eosin method. Results showed that thickness of tunica alboginea in experimental groups significantly increased compared with control group. Diameter and thickness of seminiferous tubules and number of spermatogonium A, spermatogonium B, primary spermatocyte, spermatid, spermatozoon, leydig and sertoli cells were decreased in experimental groups [p > 0.05]. The most profound effect was observed in the group which received 600 micro g/kg bw of tamoxifen. According to these findings, we concluded that tamoxifen in a dose dependent manner, via negative effects on testis, decreases the fertilization ability in adult male Wistar rats

Control of environmental health and removal of rats by alpha[2]-adrenergic antagonist and potassium channel blocker

In the present study, it is shown that in vivo oral administration of glibenclamide [1-10 mg/kg/day], an adenosine triphosphate -sensitive potassium channel blocker, and yohimbine [1-5 mg/kg/day], an alpha 2-adrenoceptor antagonist, potently reduced glycemia in male rats. Diazoxide [1-45 mg/kg/day], a potassium channel opener, and clonidine [0.05-0.5 mg/kg/day], an alpha 2- adrenoceptor agonist, antagonized the effects of glibenclamide and yohimbine respectively. Administration of glibenclamide and yohimbine separately decreased the serum glucose levels, so it was expected that coadministration of these two drugs significantly decreased this parameter in fasted animals. It is well known that glibenclamide blocks the potassium channels and it is likely that, yohimbine also blocks these channels, but according to our data, it seems that yohimbine acts via a different binding site to that of glibenclamide. In this research it is also observed that administration of yohimbine and glibenclamide causes death in rats, it seems that these drugs causes death in the experimental animals by lowering blood glucose level, which were the aim of this study and could be applied as a way to control the environmental health by abolishing rats

effects of baclofen [GABA-B receptor agonist] administration alone and accompanied with LRH-A and metoclopramid on GTH-I release in carp [Cyprinus caipio L.]

Investigation of possibility and the role of aminobutyric acid [GABA]in the fish pituitary functional regulation ,by measuring the changes in blood serum GTH-I levels. Experimental study. Fifty sexually regressing female carps. Seven experimental conditions were tested.Injection with just normal saline [control or basal] and intraperitoneal injection of Bac.[9 mg/kg], LRH-A [50 microg/kg], Met.[15 mg/kg], Bac.+LRH-A, Met.+LRH-A, Bac.+ Met.+LRH-A were done. In this study fishes were bled imediately before injection and 5 hours after then. Statistical analysis: Pre and post-treatment GTH-I values were compared by t-test and Mann-Whithney U test. Experiments indicated that only the injection of baclofen alone could produce a significant decrease in the serum GTH-I levels. Other factors, whether alone or in combination with each other did not produce acceptable changes in GTH-I secretion at least in this stage of sexual cycle. The results of the present study suggest that GAB A may be one modulator for serum GTH-I levels in the sexually regressing female carps

effects of exercise [Treadmill Running] on passive- avoidance learning and memory in morphine dependent male rats

In this research, the effects of treadmill running was studied on the passive avoidance learning and memory [PA] in matured male rats having been morphine dependent. In the behavioral stage, 36 rats weighing about 250g were housed in four groups as follows: Control; Morphine dependent; Exerciser and Exerciser's morphine dependent. Intraperitoneal injection [IP] of solved morphine with increased doses of, respectively; first three-day: 10mg/kg, second three-days 20mg/kg and third three-day, 40mg/kg were applied to make rats morphine-dependent. Treadmill running was performed in a ten-day period [two hours a day, at a speed of 12m/min and a incline of 15 degree] for the two groups of exerciser and exerciser's morphine dependent. Passive avoidance learning and memory test after attending physical exercises and making morphine- dependent were performed in similar conditions for all groups. On the basis of these results, in comparision to the average of the Control group with that of the Exerciser and Exerciser's morphine dependent groups; it is confirmed that physical activity strengthen the indicators of positive criterion [LS and Latency] and weaken the negative criterion [DS]. About the first indicator [Latency]: In the comparison of control group with the two groups of exerciser and exerciser's morphine dependent, a significant increase until 24 hours after footshock, and for the third indicator [LS] until one week after shock and for the second indicator [DS] a significant decrease until one week after shock was observed [***p<0.001, **p<0.01, *p<0.05]. In the meantime, no significant difference was observed for one month after shock [p>0.05].In comparison to control group with morphine-dependent group, except for the second indicator [DS] in which a negative criterion was considered, only a significant increase was observed 24 hours after footshock [p<0.05]. In comparison to the average of the second group [morphine-dependent] with the fourth group [exerciser's morphine-dependent], it was observed that there is a significant difference for Latency indicator until 24 hours after shock and for the indexicator of LS and DS until one week after footshock [+++p<0.001, ++p<0.01, +p0.05]. The result of behavioral steps showed that physical exercises increase the learning rate and strengthen short-term memory [STM] recalling, but it does not have any sensible effect on past event memory. Accordingly, it is said that probably some parts of hippocampus were influenced by physical activity. Moreover, physical exercise had treated the negative effects caused by morphine on the memory and learning in morphine-dependent rats, so that they recalled the past memories in the same way as the control group

Effects of cadmium on plasma cortisol and prolactin levels in the rainbow trout [oncorhynchus mykiss]

Cadmium occurs as a contaminant in freshwater systems, primarily are a result of lead mining, smelting and electroplating. In freshwater fish, prolactin and cortisol are thought to be in volved in the maintenance of ionic and osmotic balance and since this regulation is apparently disrupted by cadmium, related changes in prolactin and cortisol might occur. In view of this, it was decided to investigate the effect of cadmium on plasma cortisol and prolactin levels in the rainbow trout. The objectives of this research were to determine the LC50 values during 120 h period after acute exposure to poison of cadmium chloride. The LC50 values for 24, 48, 72, 96 hours were, found to be 7.76, 1.95, 0.5, 0.45 mg/lit respectively. Exposure of rainbow trout to 10, 1, 0.5 mg/lit cadmium during 24h did not have any change in plasma prolactin levels [p>0.05]. Exposure of fish to 0.1 mg/lit cadmium 5, 24, 48, 96 hours in tank water produced time dependent changes [p=0] in plasma prolactin levels. Exposure of trout to 0.05 mg/lit cadmium did not change plasma prolactin levels [p>0.05]. Exposure of trout to 0.05 mg/lit cadmium for 24 and 27 h. didnot have any change in plasma cortisol levels [p=0.08]. Exposure of trout to 0.1 mg/lit of cadmium in the tankwater in 5, 24, 28, 26 h. Producedtime dependent changes in plasma cortisol levels which may reflect the alarm resistance and exhaustion stages in the response of the fish to the cadmium