Physiology and Pharmacology
Volume:17 Issue: 4, 2014

Ghrelin and Orexin A exert inhibitory effects on gonadotropins secretion. Aromatase is a key enzyme in the steroidogenesis pathway which converts testosterone to the estradiol. Treatment of neonatal female rats with testosterone propionate (TP) alters gonadotropin secretion patterns in the adulthood. In the present study the effects of central injection of ghrelin or orexin A on the expression of aromatase gene in the ovaries of pubertal androgenized female rats. Forty two neonatal female rats were androgenized on the third day after birth by subcutaneous injection of 50μg TP and 6 neonatal female rats in one group received subcutaneous injection of olive oil as controls. After puberty, the animals in seven groups (n=6 in each group) received central injections of saline, different doses of ghrelin (2, 4 or 8μg) or Orexin A (2, 4 or 8μg). The ovaries were removed bilaterally and frozen. Aromatase gene expression levels was determined by semi quantitative RT-PCR. The mRNA levels of aromatase (CYP19) increased significantly in the ovaries of the androgenized rats compared to the control group. Orexin A and ghrelin injections significantly decreased aromatase gene expression compared to the androgenized rats (P <0.05). Androgens may stimulate aromatase gene expression in the ovaries. Orexin A and ghrelin may exert inhibitory effects on reproductive axis partly via reducing the expression of genes involved in the steroidgenesis.

Arginine-phenylalanine-amide-related peptide-3 (RFRP-3) is an inhibitor of gonadotropin releasing hormone (GnRH) secretion and an appetizer. Kisspeptin is a stimulator of GnRH and a regulator of energy metabolism. The objectives of the present study were to compare the effect of long term malnutrition on expression of RFRP-3 mRNA in dorsomedial hypothalamic nucleus (DMH) and KiSS-1 mRNA in arcuate nucleus (ARC) of rat hypothalamus. Sixteen female ovariectomized rats of the Sprague-Dawley strain were randomly allotted into three groups. After 2 weeks recovery period, one group was fed with perfect diet (rat standard feed) and the other group was fed with the half dietary of perfect diet for 14 days. The control group (n=4) were sacrificed 2 weeks after surgery (day 0). Relative expression of RFRP-3 and KiSS-1 mRNAs (compared to the control group) were measured using real-time PCR method in DMH and ARC of hypothalamus, respectively. Mean and SE of relative expression of RFRP-3 mRNA in DMH in the half dietary rats was higher than that of the perfect diet ones (P=0.01). Relative expression of KiSS-1 mRNA in ARC was not different between two groups of rats (P=0.1). Long term malnutrition (2 weeks) increased RFRP-3 mRNA expression in DMH of rats hypothalamus, but had no effect on KiSS-1 mRNA expression in the ARC nucleus of ovariectomized female rats.

Uncontrolled diabetes mellitus could lead to neuropathy in central and peripheral nerve tissues and one of its main signs can be hyperalgesia and motor coordination defect. Due to the blood glucose lowering effect of Thymus species and the presence of polyphenolic compounds with high antioxidant capacity, in this study the effect of Thymus caramanicus jalas extract was investigated on animal model of diabetes-induced neuropJavascript:FormatThis(''B'')athy. In the present study development of hyperalgesia was examined by tail-flick and rota-rod tests, in streptozotocin-induced diabetic male wistar rats (subcutaneous injection). Animals were given Thymus caramanicus jalas extract (50, 100, 150 and 200 mg/kg) for 6 weeks. The levels of blood glucose were measured at the beginning and the end of the experimental period. Blood glucose levels in diabetic animals which received Thymus extract at the doses of 150 and 100 mg/kg was reduced as compared to the pretreatment levels (p<0.05 and p<0.01, respectively). Untreated diabetic rats showed lower threshold in pain sensation and motor deficit compared with the control animals. However, tail-flick latency and ability to stay on rota-rod were significantly decreased in diabetic animals that received 100 mg/kg (p<0.01) and 150 mg/kg (p<0.001) of extract. The data show that Thymus caramanicus jalas extract has ability to reduce serum glucose levels and attenuate hyperalgesia and motor deficit induced by diabetes in rats. The mechanisms of this effect may be related to (at least in part) the attenuation of blood glucose and prevention of neural damage.

Diabetes mellitus is a metabolic disorder and it is estimated that its annual incidence rate will continue to increase in the future worldwide. Increased oxidant factors and decreased antioxidant defense are two of the factors resulting in diabetes. In the present study, we aimed to investigate Citrullus Colocynthis pulp effects on oxidant and antioxidant factors of liver in streptozotocin-induced diabetic rats. Thirty-two male rats were divided into four groups eight each: N (normal) group, N+C group, D (diabetic) group, and D+C group. Groups N and D received normal saline 2ml orally for 2 weeks and Groups N+C and D+C received 10mg/kg Citrullus Colocynthis pulp orally for 2 weeks. Diabetes was induced by a single intraperitoneal injection of streptozotocin (STZ) at 65 mg/kg. Diabetic group had a significant increase in H2O2 (Hydrogen peroxide), MDA (malondialdehyde) and CAT (catalase) activity and a significant decrease in POD (peroxidase) activity in liver tissues compared to N and D groups. Group D+C had a significant decrease in H2O2, MDA, and CAT concentrations in liver tissues and significant increase in POD activity in liver tissues compared to D group. These results suggest that treatment of diabetic rats with Citrullus colocynthis pulp decreased oxidant stress and support antioxidant defense in liver STZ-Induced diabetic rats.

Memory impairment is one of the complications of diabetes which may accompany with changes in expression of apoptotic and antiapoptotic genes. The aim of the present study was the evaluation of intra-hippocampal injection of aminoguanidine (AG), as an antioxidant and inducible nitric oxide synthase inhibitor, on passive avoidance memory and Bcl-2 family genes expression in diabetic rats. Diabetes was induced in male rats using streptozotocin (STZ) (50 mg/kg, i.p). AG (10 and 90 μg/rat) was injected by intra-hippocampal implanted cannulae. Passive avoidance memory was assessed 7 weeks later. Then, animals were killed and hippocampus was removed. The expressions of Bcl-2, Bcl-xLand Bax mRNA were measured using semi-quantitative RT-PCR technique. Diabetes caused significant impairment in passive avoidance memory. None of the AG doses improved the memory impairment. In diabetic rats, the levels of Bcl–2 and Bcl-xL were decreased in hippocampus while the expression of Bax, Bax/Bcl-2 and Bax/Bcl-xL was increased. In comparison to diabetic control group, AG treatment increased the levels of Bcl–2 and Bcl-xL but decreased Bax/Bcl–2 and Bax/Bcl-xL. Although AG was not associated with the significant improvement of memory but it modified the expression of the apoptosis involved genes in hippocampus of STZ-induced diabetic rats.

Topiramate is an anti-convulsant drug, which produces its effects via glutamate metabotropic receptors inhibition and/or GABA receptor excitation. In the present study, attempts were made to investigate the effects of topiramate on the tolerance to morphine-induced analgesia activity in male NMRI mice (20-30 g). Hot plate method was chosen for the study. First of all the analgesic effects of morphine and topiramate on mice were investigated. Then, the animals became tolerant to morphine (50 mg/kg; twice daily for three consecutive days). Different doses of topiramate were administered to the animals 30 min before each morphine (50 mg/kg) injections (acquisition) during tolerance development or on the test day, 30 min before the experiment. Subcutaneous morphine injection (10 mg/kg) induced analgesia. However, intraperitoneal administration of topiramate (0.5, 2.5 and 5 mg/kg) had no effect. In addition, topiramate (0.5, 2.5 and 5 mg/kg) did not affect morphine-induced analgesia. Administration of a single daily dose of morphine (50 mg/kg; twice daily) for 3 days, induced tolerance. Injections of topiramate (0.5 and 2.5 mg/kg) had no effects on the acquisition of morphine tolerance. However, topiramate (0.5 and 2.5 mg/kg) enhanced the expression of morphine tolerance. The drug reduced the expression of morphine tolerance at the dose of 5 mg/kg. Topirmate showed a biphasic effect on the expression of tolerance to morphine-induced analgesia in lower and higher doses which may be due to glutamate and/or GABAergic mechanisms.

Iron plays an important role in physiological processes as a trace element. Today, iron oxide nanoparticles have attracted extensive attention due to their super paramagnetic properties and a variety of potential applications in many fields. The main objective of this study was to evaluate in vitro and in vivo toxic effects of the iron oxide nanoparticles on L929 cell line, kidney and liver function, in order to achieve a safe application of the mentioned nanoparticles. The toxicity effects of 200 and 800 μg/ml iron oxide nanorods on L929 were determined using (3-(4, 5- dimethylthiazol-2-yl) -2, 5-diphenyltetrazolium bromide)MTT (test. One and 24 h after the injection of iron oxide via tail vein, serum iron, blood urea nitrogen (BUN) and liver enzymes (ALT, AST, and ALP) were measured as indicators of the kidney and liver function, respectively. Histopathological studies on liver and kidney was carried out using light microscopy following tissue processing steps and standard H&E staining. The viability of the cells exposed to iron oxide nanorods, was decreased with increasing dose. No significant differences were observed between biochemical factors, 1 and 24 h after the injection of nanoparticles. Serum iron level showed no difference with control 1 h after the injection. However, it exhibited a significant increase 24 h after the injection as compared to the control. Meanwhile, pathological studies did not show any acute toxic damage. Use of the iron oxide in short-time and in doses less than 800μg/ml may be safe. More studies are needed for accurate assessment of the toxicity of these particles in terms of dose، time and the type of covering.

Ethanol can induce a wide spectrum of neurophysiological effects via interaction with multiple neurotransmitter systems and disruption of the balances between inhibitory and excitatory neurotransmitters. Prefrontal cortex is involved in cognitive process including working memory and is sensitive to ethanol. Present study investigates the effects of intraperitoneal (i.p.) administration of multiple doses of ethanol and intra-prefrontal cortex (i.c.) administration of ethanol on spatial working memory performance. Adults male wistar rats (200-250g) were used. Rats in various groups received saline (i.p.), saline (i.c.), ethanol (10%, 20% and 30%, i.p.) and ethanol (30%, i.c.). Surgery for intra-prefrontal cortex cannulation was performed for i.c. administrations. The spatial working memory was assessed 15 and 30 minutes after i.p and 5 minutes after i.c. injections at first, second, and third day using the 8-shape maze apparatus. Ethanol (10%, i.p.) had no significant effects, but 15 and 30 min after administrations of ethanol (20%, i.p.) (P<0.05), and 15 min after administration of ethanol (30%, i.p.) (P<0.001), spatial working memory performance decreased significantly. Only i.c. administration of ethanol 30% at the first day, diminished working memory performance (P<0.001). Because working memory was impaired in both intraperitoneal and intra-prefrontal cortex administration, therefore probably a part of spatial working memory deficits is related to effects of ethanol on prefrontal cortex and disruption of neuronal circuits involved in working memory in this region.

Consumption of vitamin D3 is effective to reduce intensity of autoimmune diseases such as multiple sclerosis. Neurons of the central nervous system are constantly exposed to reactive oxygen species and these factors play a key role in the destruction of myelin and damage of axons. The hippocampus is a vital center for learning and memory in central nervous system. This area is extremely vulnerable to neurodegenerative diseases and oxidative damage. In the present study the effects of vitamin D3 on learning, spatial memory and lipid peroxidation following demyelination of rat hippocampal CA1 neurons was investigated. For demyelination induction, 2μl lysolecithin was injected into the CA1 area of rat brain using stereotaxic surgery. After induction of demyelination, animals received 5 μg/kg vitamin D3 for 7 days. The learning and spatial memory of rats were investigated by radial maze. The extent of demyelination in hippocampus was studied using myelin specific Luxol fast blue staining. On day 7, lipid peroxidation was evaluated by Esterbauer and cheeseman methods. The results of this study showed that administration of vitamin D3 caused significant improvement of spatial learning and memory compared to the group receiving lysolecithin alone (p<0.001). Levels of lipid peroxidation in group treated with vitamin D3 showed significant reduction compared to the group receiving lysolecithin alone (p<0.01). Vitamin D3 acts as an antioxidant agent and caused improvement in learning and spatial memory through reduction of demyelination and lipids peroxidation products.

Considering the importance of uterine contractions in uterus retraction and reducing post-partum hemorrhage and the current findings on the effect of the alcoholic extract of pomegranate seed on the uterine contractility, only few studies were made on this issue. In the present study the cumulative effect of the aqueous extract of pomegranate seed on the uterine smooth muscle contractility of virgin rats were studied. This experimental study was made on 12 strips taken from the middle part of the uterine of rats (Sprague Dawley, weight 200-250 g). During the experiments the cumulative effect of the aqueous extract of pomegranate seed (2, 22, 222, 2222, 22222 μg/ml) on the basal activity of rat uterine muscle was studied. The data were analyzed using repeated measure tests at the significance level of p<0.05. The cumulative effect of different concentrations of the aqueous extract of pomegranate seed significantly increased the contractile response of uterine smooth muscle in a dose-dependent manner (p<0.05). The aqueous extract of pomegranate seed could have potentials for the treatment of post-partum hemorrhages.

Alzheimer’s Disease (AD) is a chronic neurological disorder characterized by memory impairment, cognitive dysfunction, behavioral disturbances, and deficits in activities of daily living. AD has been found to be associated with a cholinergic deficit in the post-mortem brain characterized by a significant decrease in acetylcholine amount and loss of cholinergic neurons of the nucleus basalis of Meynert (NBM). This study investigated the effect of Zizyphus jujuba (ZJ) extract on motor activity in NBM-lesioned rat model of AD and intact rats. In this study, 49 wistar rats were divided into 7 groups. Rats received bilateral electrolytic lesions of the NBM. The control and sham group received distilled water while NBM-lesioned groups received ZJ extract via gastric gavage for 20 days. Intact rats received ZJ extract for 20 days without any surgery. The motor activity assessed with rota-rod apparatus. Data were compared using one way ANOVA followed by LSD post test. ZJ extract for 20 days improved motor activity in NBM-lesioned rats and intact rats that received extract at the dose of 1000 mg/kg. Results suggest that ZJ extract can improve the motor coordination both in NBM-lesioned rats and in intact rats.

Epilepsy is one of the most common neurologic disorders. Pharmacoresistance and adverse effects of current antiepileptic drugs (AEDs) necessitate development of new drugs and strategies for treatment of epilepsy. Omega 3-Polyunsaturated fatty acids (ω3-PUFAs) are safe nutritional supplements that recently considered for treatment of epilepsy. Anticonvulsant effect of docosahexaenoic acid (DHA), the most fatty acid in the brain and neural membrane with important role in modulation of neuronal function, is reported by some researchers. In the present study, the anticonvulsant effect of DHA (before conversion to metabolites) was examined in pentylenetetrazole (PTZ) and maximal electroshock (MES) model of seizures. Different doses of DHA (0.01, 0.03, 0.075, 0.3, 300 and 1000 μM) were injected into lateral cerebral ventricles (i.c.v.) of adult male NMRI mice. After 15min, clonic seizures were induced by PTZ (60 mg/kg, i.p.) or tonic seizures were induced by maximal electroshock (MES, 50mA, 50Hz, 0.5sec duration). Sodium valproate and phenytoin were injected i.p. as positive control groups for PTZ and MES tests, respectively. Latency to seizure occurrence, number of protected mice and any abnormal behavior in mice were recorded. DHA did not show any protective effect in MES model but increased the latency of seizures and inhibited clonic seizures induced by PTZ with ED50 value of 0.1 μM. Acceptable anticonvulsant activity, good tolerability and low price could suggest DHA as a good candidate for design and development of new anticonvulsant medications.