Characteristics of Depressive-Like Behavior of Prenatally Stressed Male Rats with Androgen Deficiency.

Characteristics of depressive-like behavior of male rats with androgen deficiency born by mothers subjected to prenatal stress during pregnancy were assessed by using Porsolt tests and open-field tests. The level of depression-like behavior in prenatally stressed males increased more intensively than in non-stressed gonadectomized males. Chronic administration of testosterone propionate (0.5 mg/kg, intramuscularly, for 14 days) increased depressive behavior in prenatally stressed gonadectomized males in contrast to its antidepressant effect in nonstressed gonadectomized rats. Prenatal stress considerably exacerbated depressive behavior of male rats under conditions of androgen deficiency and abolished the antidepressant effect of exogenously administered testosterone propionate.

Effects of SCH-23390 and sulpiride on active avoidance in ovariectomized rats treated with a low dose of 17ß-estradiol.

We studied the effects of dopamine D1/D2 receptor antagonists on the dynamics of acquisition and extinction of active avoidance responses and open field behavior in ovariectomized female rats. Dopamine D1 receptor antagonist SCH-23390 (0.1 mg/kg intraperitoneally) and dopamine D2 receptor antagonist sulpiride (10.0 mg/kg intraperitoneally) were administered chronically (14 days) either alone or in combination with a low dose of 17ß-estradiol (0.5 µg per rat subcutaneously) to females after ovariectomy. It was found that SCH-23390 in combination with a low dose of 17ß-estradiol completely restored impaired conditioning and retention of a conditioned avoidance response in ovariectomized animals. Simultaneous correction of behavioral patterns in the open field test was also observed in ovariectomized females receiving SCH-23390. Sulpiride injected alone or in combination with low dose of 17ß-estradiol did not correct conditioning and reproduction of active avoidance response in females with estrogen deficiency and did not significantly affect animal behavior. The results indicate positive effect of dopamine D1 receptor blockade on active learning under conditions of estrogen deficiency.

[Co-administration of RJR-2403 with low dose of 17beta-estradiol on spatial learning in ovariectomized rats].

The aim of this work was to study the influence of stimulation or blockade Nalpha7-cholinoreceptors on dynamics of spatial learning in water Morris maze and on behavior in the "open field" test in adult ovariectomized (OVX) females given with a low dose of 17beta-estradiol. Agonist of Nalpha7-cholinoreceptors - RJR-2403 (1.0 mg/kg, i.p.) or antagonist of Nalpha7-cholinoreceptors - mecamylamine (1.0 mg/kg, i.p.) treated chronically (14 days) alone and in a combination with low dose of 17beta-estradiol (0.5 micro/rat, s.c.) to OVX rats. Co-administration of RJR-2403 with low dose of 17beta-estradiol completely restored impaired spatial learning in water Morris maze in OVX females. Moreover, OVX rats treated with RJR-2403 and low dose of 17beta-estradiol demonstrated increased exploratory and grooming behavior in the "open field" test. Both mecamylamine alone and in combination with low dose of 17beta-estradiol failed to influence on spatial learning and failed to modify behavior in the "open field" test in OVX rats. The results of the present study suggest a positive effect of RJR-2403 in combination with low dose of 17beta-estradiol on spatial learning at estrogen deficiency.

Effects of prenatal stress on the activity of the pituitary-ovarian system in female rats.

The comparative analysis of hormonal status was performed in mature female rats with experimental deficiency of estrogens, which mothers were exposed to stress during pregnancy. High levels of follicle-stimulating hormone and luteinizing hormone, and significantly lower amount of estradiol were observed in intact prenatally stressed females in comparison with intact non-stressed female rats. The increase in the levels of follicle-stimulating hormone and luteinizing hormone, and the decrease in estradiol concentration were more pronounced in blood serum of prenatally stressed ovariectomized rats as distinct from intact non-stressed and prenatally stressed female rats, and non-stressed ovariectomized female rats. We can conclude that prenatally stressed ovariectomized rats were characterized by an increased sensitivity to exogenous hormonal interventions and high lability of functional state of the pituitary-ovarian system.

[Influence of fluoxetine and paroxetine on anxiety-like behavior in young and adult prenatally stressed male rats].

The aim of the present work was an estimation of effects of chronic administration of selective serotonin reuptake inhibitors--fluoxetine (5.0 mg/kg, p.o.) and paroxetine (5.0 mg/kg, p.o.) for 14 days of postnatal period on anxiety-like behavior in the prenatally stressed male rats during pubertal period (1,5 month) and the adult state (3 month). Chronic paroxetine administration to females failed to change an anxiety-like behavior independently from age. On the contrary, administration of fluoxetine resulted in modulating influence on the anxiety-like behavior of prenatally stressed rats dependently from age: anxiolytic effect was noted in young males, while anxiogenic effect was observed in the adult male rats.

[Influence of fluoxetine and paroxetine on anxiety-like behavior in young and adult prenatally stressed male rats].

We present the results of a comparative analysis of the effects of the chronic administration of the selective serotonin reuptake inhibitors fluoxetine (5.0 mg/kg, p.o.) and paroxetine (5.0 mg/kg, p.o.) for 14 days of the postnatal period on anxiety-like behavior in the prenatally stressed male rats as studied during pubertal period (1.5 month) and in the adult age (3 month). The chronic administration of paroxetine in male rats did not change the anxiety-like behavior in male rates of any age. On the contrary, the administration of fluoxetine modulated the anxiety-like behavior of prenatally stressed rats depending on the age: the anxiolytic effect was observed in young males, while the anxiogenic effect was observed in adult male rats.

Blockade of 5-HT2A/2C-type receptors impairs learning in female rats in the course of estrous cycle.

We studied the effects of chronic administration (14 days) of agonist of 5-HT2B/2C serotonin receptors m-CPP (0.5 mg/kg subcutaneously) and agonist of 5-HT2A/2C serotonin receptors ketanserin (0.1 mg/kg intraperitoneally) on conditioned reactions in female rats in different phases of the estrous cycle. Passive avoidance (PA) paradigm and Morris water maze were used as behavioral tests. Chronic administration of m-CPP did not affect PA retrieval during the proestrus and estrus phases, but improved the dynamics of spatial learning in Morris water maze in comparison with control rats. Chronic administration of ketanserin uniformly impaired processes of spatial and nonspatial learning in female rats irrespective to the phase of the estrous cycle. A modulating role of 5-HT2A/2C and 5-HT2B/2C serotonin receptors in process of learning in female rats during the key phases of the estrous cycle was demonstrated.

Pharmacological correction of testosterone deficiency during experimental myocardial ischemia.

Experiments on rats with myocardial ischemia modeled by occlusion of the left coronary artery aggravated by alimentary dislipoproteinemia showed that therapy with taurepar (50 mg/kg), a taurine derivative, decreased blood corticosterone concentration and increased the level of endogenous testosterone, which attests to normalization of the compensatory-adaptive and gonadotropic functions of the organism.

Effects of 8-OH-DPAT and NAN-190 on anxious-depressive-like behavior of female rats during the estrous cycle.

We studied the effect of chronic administration of 5-HT(1A)-receptor agonist 8-OH-DPAT (0.05 mg/kg subcutaneously) or antagonist NAN-190 (0.1 mg/kg intraperitoneally) for 14 days on anxious-depressive-like behavior of female rats during the key phases of the estrous cycle. Chronic administration of NAN-190 during the estrus phase produced an anxiogenic effect, while its administration during proestrus phase induced an anxiolytic effect. Administration of 8-OH-DPAT had no effect on anxiety level, but produced a pronounced antidepressive effect irrespective of the phase of the estrous cycle.

Antiamnesic effect of combined treatment with galantamine and estradiol in middle-aged ovariectomized female rats.

The effect of chronic combined treatment with galantamine and 17beta-estradiol on passive avoidance retention was studied in middle-aged ovariectomized female rats (15 months) with scopolamine-induced amnesia. Combined treatment with galantamine and estradiol completely restored retrieval of memory traces in middle-aged ovariectomized female rats.

Antiamnestic effect of alpha7-nicotinic receptor agonist RJR-2403 in middle-aged ovariectomized rats with Alzheimer type dementia.

The effects of chronic combined treatment with alpha7-nicotinic cholinergic receptor agonist RJR-2403 (1.0 mg/kg intraperitoneally) or alpha7-nicotinic cholinergic receptor antagonist mecamylamine (1.0 mg/kg intraperitoneally) and 17beta-estradiol (0.5 microg per rat intramuscularly) for 10 days on passive avoidance retention were studied in middle-aged (15 months) ovariectomized rats with experimental Alzheimer type dementia. Chronic treatment with RJR-2403 and 17beta-estradiol had a pronounced antiamnestic effect under conditions of Alzheimer type dementia in middle-aged ovariectomized rats.

Combined administration of NAN-190 and 17beta-estradiol abolishes the amnesic effect of scopolamine in middle-aged ovariectomized rats.

Chronic combined administration of 5-HT1A receptor antagonist NAN-190 and 17beta-estradiol improved conditioned passive avoidance performance in middle-aged ovariectomized rats with scopolamine-induced amnesia. Our results suggest that the ovarian hormonal, cholinergic, and serotoninergic systems play a role in age-related cognitive disturbances under conditions of hypoestrogenic syndrome.

Effect of dehydroepiandrosterone on avoidance behavior of adult male rats.

We studied the effect of repeated intraperitoneal treatment with dehydroepiandrosterone in doses of 0.1 and 0.7 mg/kg on conditioned-response activity and behavior of adult male rats. The effect of dehydroepiandrosterone on learning was estimated in conditioned active and passive avoidance response paradigms. Chronic administration of dehydroepiandrosterone in low and high doses had no effect on retention of conditioned passive avoidance response in adult male rats 24 h after learning. However, chronic administration of dehydroepiandrosterone in low dose impaired acquisition of the conditioned active avoidance response. It should be emphasized that chronic administration of dehydroepiandrosterone in high dose did not modulate acquisition and retention of this reaction.

Modulatory effect of 8-OH-DPAT on behavior of ovariectomized female rats.

Behavior of ovariectomized rats was studied after chronic administration of serotonin 1A receptor agonist 8-OH-DPAT alone or in combination with 17beta-estradiol for 14 days. The effect of 8-OH-DPAT on learning was evaluated in the conditioned passive avoidance task. Behavioral activity in elevated plus-maze and open field was recorded. Administration of 8-OH-DPAT to ovariectomized female rats increased the number of entries into open arms of the maze and the time spent there. Combination treatment of ovariectomized animals with 8-OH-DPAT and 17beta-estradiol decreased total locomotor and emotional activity in the open field. Administration of 8-OH-DPAT alone or in combination with 17beta-estradiol improved performance of the conditioned passive avoidance response.

The effect of L-tryptophan on conditioned reflex learning and behavior in rats with experimental pathology of the thyroid gland.

The effects of L-tryptophan on conditioned reflex learning and behavior were studied in male rats with deficient and excess thyroid hormones levels. The learning process was studied using a model consisting of a conditioned active avoidance response; animal behavior was assessed in an open field test. These studies showed that in conditions of thyroid hormone deficiency. L-tryptophan had positive effects on the acquisition and reproduction of the active avoidance reflex, restoring the ability of the animals to learn actively; L-tryptophan increased investigative activity in the open field test. In conditions of increased thyroid hormone levels, L-tryptophan reversed the mild stimulating effects of thyroid hormones on the processes of developing and performing the active avoidance habit, and increased investigative activity, but decreased the amount of grooming.