[Age-related aspects of male rats sexual behavior with different senescence rates].

Social and sexual behavior of males Wistar and senescence-accelerated OXYS rats was studied. The experimental model excluding direct interaction between partners showed that the exploratory activity decreased with aging in rats of both strains, but social motivation didn't change. No interstrain differences in intensity of sexual motivation in the presence of an inaccessible receptive female were observed in 4-month rats. The level of sexual motivation of 12-month Wistar rats didn't differ from that of 4-month animals. However, in 12-month OXYS males, sexual motivation was decreased as compared to both 4- and 12-month Wistar rats. The same regularities were found under conditions of direct interaction with a partner. Behavioral changes in 12-month OXYS rats were considered as genetically determinate abnormality at the initial stage of sexual behavior, i.e., sexual motivation. The results suggest the accelerated senescence of the reproductive system of OXYS rats.

[Social isolation and social instability in adolescence in rats: immediate and long-term physiological and behavioral effects].

After weaning on the 21th day, offspring of Wistar rats were reared in groups of 4-5 (controls), singly (social isolation), or exposed to alternate days of isolation and housing in groups of 10 with partner rotation (social instability) for 6 weeks. Then, a part of the rats was decapitated and the remaining young animals were tested and left undisturbed for 2 months in stable groups of 4-5 animals. Adults were tested repeatedly. The weight of the body, thymus and adrenals, resting and acute stress-induced plasma corticosterone levels and basal testosterone concentration, resting and stress-induced systolic blood pressure, amplitude and prepulse inhibition of acoustic startle reflex, anxiety- and depression-related behavior were studied in young and adult rats. It was shown that social environment in adolescence can affect the physiological and behavioral responses, some of the effects being transient blunted by subsequent rearing in stable groups, yet others still persisted with age or were clearly manifested in adults only.

[Age-related aspects of male reproductive function in rats with normal and accelerated senescence].

The study was performed on male rats with normal rate of aging (Wistar) and senescence-accelerated OXYS rats. Sexual motivation behaviour, activation of endocrine testicle function under condition of sexual activation, gravimetric rates were studied in male rats of different age. Potential ability to spermatogenesis in testis was studied in 14-month male rats. Males underwent the partition test: a receptive female was introduced into the male's cage, but the male and female were separated by a transparent partition. The number of approaches to the partition and total time spent near partition during the test served as an index of sexual motivation. Activation of hypothalamic-pituitary-testicular complex was estimated by plasma testosterone level. A decrease of sexual motivation in the 14-month OXYS males was observed in comparison both with 3- and 6-month OXYS rats and with 14-month Wistar rats. However, no decrease in hormonal component of sexual arousal in aged OXYS males rats was detected. No interstrain differences in potential ability to spermatogenesis in 14-month rats were observed. However, no interstrain differences in the weights of androgen-dependent reproductive organs (testes and preputial glands) were observed under 18-month age. However, the weight of epididymisis in 24-month OXYS rats was significantly smaller than in Wistar rats.

[Chronic imipramine treatment normalizes decreased sexual motivation and high predisposition to catalepsy induced by propylthiouracil in rat].

Thyroxine synthesis inhibitors produced augmentation in predisposition to catalepsy and a decrease of sexual motivation and acoustic startle reflex response in rat. Sensitivity of these behavioral alterations to antidepressants was unknown. Chronic treatment with prototypical antidepressant imipramine (15 mg/kg, 21 days) prevented manifestation of catalepsy expression and sexual motivation reduction in Wistar rats given propylthiouracil (50 mg/l, 28 days) but did not influence startle reflex amplitude. Behavioral recovery induced by imipramine did not attribute to alterations in locomotor activity in open-field test or body weight gain. 5-HT(2A)-receptor mRNA level in the frontal cortex was not changed either. Model of sexual motivation disturbance and catalepsy induced by propylthiouracil in rat seems to be prospective to study the role of thyroid dysfunctions in mechanisms of depression and antidepressant treatment.

[Influence of age and sex on hepatotoxic and hypothermic effects of estrogole in mice].

Some physiological effects of estragole under a single intraperitoneal injection in oil solution were studied in GR mice; elevation of blood aminotransferases activity, body temperature and animals lethality were registered. At a dose of 600 mg/kg, estragole killed 100% sucklings of both sexes and 90% adult females but no any adult male. The males aquire resistance to estragole at the time of maturation. Exogenous testosterone administered at the dose of 50 mg/kg 4-2 days earlier increases the resistance of female mice to estragole up to its level in males. However, neonatally androgenized females are as sensitive to the toxic action of estragole as the males. At the dose of 900 mg/kg, estragole defeats adult males as well: significant elevation of aminotransferase activities in their blood is indicative of this. In this case, the enzyme activity reaches its peak after 2-3 days, not at the 1st day as in the case of carbon tetrachloride administration. We have discovered a strong hypothermic effect of estragole which appears to be unrelated to its hepatotoxicity and testosteron level.

[Activity balance in behavioural inhibition and behavioural approach systems and rest blood pressure in humans].

The study determined the contribution of activity balance of the two motivational systems, i.e. appetitive and defensive, into mechanisms of blood pressure (BP) regulation in humans. Average age of participants was 30.29 +/- 9.8 years. Men having the BP within normal range and the individuals with firstly diagnosed increased arterial blood pressure up to abnormal values were selected. Using the method of emotional modulation of the startle reflex (EMSR) by different profiles of the EMSR. The participants with shifted balance toward enhanced activity of defensive system (amplified probe startle by unpleasant context) or shifted balance toward low activity of appetitive system (decrease or inhibition of the probe startle by pleasant context) had significantly increased BP in resting. Putative mechanisms of the revealed phenomena are discussed.

[The effects of neonatal saline injections on behaviours in DBA/2 male mice].

DBA/2 male mice were exposed to the injections of the saline (0.01 ml/g i.p.) on 1-th, 3-th, 5-th, 7-th, 9-th days after birth. Intact males were used as a control group. Adult saline-treated males displayed the increased number of crossed squares, entries in the centre and time spent in the centre during the open "field" test in comparison with intact animals. The time spent in the light compartment of the light-dark box was decreased in saline treated mice compared with intact animals. During the test of acoustic startle response the magnitude of startle reflex and prepulse inhibition didn't change the startle reflex. Saline administration in males did not affect corticosterone basal level. Sexual motivation was revealed to decrease in saline treated males. These data suggest that neonatal administration of saline induced a stable behavioral syndrome in adult DBA/2 male mice: hyperactivity, a decrease of open space fear and simultaneously an increase of some indices of anxiety.

[The effect of neonatal administration of monosodium glutamate on behavior and blood corticosterone level].

DBA/2 male mice were treated with monosodium glutamate (MSG) in a dose of 4 mg/g on 1, 3, 5, 7, 9 days after birth. Saline treated and intact males were used as control groups. MSG treated males displayed decreased number of crossed squares, rearings, entries in the centre and time in the centre of open field in comparison with saline-treated but not intact animals. Time in the light compartment of the light-dark box was increased in MSG-treated mice versus both saline treated and intact animals. MSG administration reduced acoustic startle response but did not affect the magnitude of prepulse inhibition of the startle reflex. Sexual motivation in male mice was reduced by MSG, the same trend was observed after saline treatment. MSG administration increased corticosterone basal level 4-fold while saline treatment did not affect it. These data suggest that neonatal administration of MSG decreases locomotion, exploratory activity, anxiety in male mice, while corticosterone level is increased. Saline treatment increases these parameters (except sexual motivation), and this augmentation is not connected to changes in corticosterone basal level.

[The stress effect in the prenatal period on sexual excitation and sexual orientation of the mice males].

Estrus female behind holed transparent partition produced sexual motivation and sexual arousal in males. It was manifested in behavioral changes (an increase in time spent near the partition) and the testosterone level augmentation in blood. Female mice were exposed to stress (1 h/day restraint) in the last week of gestation. Prenatal stress was shown to decrease the blood corticosterone level as well as to diminish sexual motivation and sexual arousal in adult male mice. Estrus female exposure produced a lesser behavioral response and a lesser testosterone level augmentation. No changes in weight of testicles, seminal vesicles or adrenal glands were found, but preputial gland weight increased. In prenatally stressed males, a female preference decrease and a male preference increase were revealed in the partner preference test. These data suggest that prenatal stress decreases sexual motivation in males and leads to clear predisposition to homosexuality, although it does not produce complete inversion of sexual orientation.

[Sodium glutamate on some physiological features and chemically induced hepatocarcinogenesis in neontal period in male mice].

A single injection of diethylnitrosamine 50 mg/kg to 12-day old CBA mice led to development of 50.7 +/- 4.8 liver tumor nodules in males and 3.6 +/- 0.8 nodules in females. Only 19.0 +/- 3.6 tumor nodules developed in the liver of males who, prior to the carcinogen, received 5 intraperitoneal injections of monosodium glutamate (2-4 mg/g on alternate days from 1st to 9th days after birth). The glutamate-treated animals' body size diminished, as well as their weights of testes and seminal vesicles and blood testosterone concentration but, as a rule, quantity of body fat increased. The data obtained indicate that neonatal administration of monosodium glutamate to mice leads to disturbance of functional activity of sex steroids and presumably other hormones taking part in regulation of metabolism of body fat and energy.

[The effect of social isolation during juvenile period on the sexual arousal in adult rats].

The effects of chronic postweaning social isolation combined with subsequent resocialization on the sexual arousal were studied in male rats with inherited stress-induced arterial hypertension (ISIAH strain) and in Wistar rats. Young males were isolated on the Day 21 of postnatal life for 6 weeks. Then they were kept in groups of 5. 4-month males underwent the partition test: a receptive female was introduced into the male's cage, but the male and the female were separated by a transparent partition. The number of approaches to the partition and total time spent near the partition during the test served as an index of sexual motivation. Hormonal component of sexual arousal was estimated by measuring plasma testosterone level. No interstrain differences in magnitude of the sexual arousal were observed. However, chronic social isolation during juvenile period caused a genotype-dependent diminution of sexual motivation in the adult male rats of both strains. The decrease of sexual motivation in ISIAH rats was more pronounced as compared to Wistar rats. Moreover, the social isolation during the juvenile period completely abolished the female-induced rise in plasma testosterone in ISIAH and Wistar male rats. Plasma corticosterone level was increased during the period of sexual arousal, but this rise of corticosterone was not affected by the social conditions during postweaning period.

[Hypothalamic monoamines in the cold stress during changes in activity of nitric oxide system]. / Monoaminy gipotalamusa pri kholodovom stresse na fone izmenenii aktivnosti sistemy oksida azota.

Effects of NO-synthase inhibitor N(omega)-nitro-L-arginine (LNA) and donor sodium nitroprusside (SNP) on alteration in body temperature, plasma corticosterone level and hypothalamic monoamines in response to cold exposure, were studied. Drop of the body temperature in cold exposure in rats treated with LNA or SNP was the same as in the control group. Administration of SNP (2 mg/kg i.p.) significantly increased the basal level of corticosterone (CS). Cold exposure elevated CS in all groups of rats. LNA did not markedly alter the hypothalamic noradrenaline (NA) while SNP significantly decreased the NA. Cold exposure resulted in additional decrease of the NA in SNP-treated rats. NA was found to significantly increase within 48 hrs following the cold exposure in the LNA as well as in the SNP groups. SNP significantly increased basal dopamine and DOPAC levels. Cold exposure did not affect hypothalamic dopamine. In the experiments, NO changes of serotonin and 5-hydroxyindoleacetic acid were observed. The findings suggest that antagonistic effects of the NO-synthase inhibitor and NO donor postulated in literature for various kinds of stress do not occur in experiments with cold stress.

[Effect of cross-fostering on catalepsy and the brain monoamine level in rat offspring prone to catalepsy and in the control strain]. / Vliianie perekrestnogo vospitaniia na proiavlenie katalepsii i soderzhanie monoaminov mozga u krysiat katalepticheskoi i kontrol'noi linii.

Duration of cataleptic reactions in male rats of Wistar and GC strains depended both on the genotype and on the type of rearing: it was longer in the GC rats than in the Wistar ones. In the GC males reared by Wistar foster mothers this parameter was smaller than in the control GC but higher than in Wistar rats. The NA content was significantly lower in the GC cortex, hypothalamus and striatum, and the level of serotonin and 5-HIAA was lower in cortex of the GC as compared with Wistar rats. The cross-fostering affected monoamine content in some brain structures. On the whole, serotonin, DA and NA systems of the GC rats proved to be more susceptible to stress caused by cross-fostering than those of the Wistar rats. The cross-fostering diminished interstrain differences in the NA level in cortex, striatum, and hypothalamus.

[Effect of chronic stress in prepubertal period on sexual arousal in the male rats]. / Vliianie khronicheskogo stressa v prepubertatnom periode na proiavlenie polovoi aktivatsii u vzroslykh samtsov krys.

Effects of two models of chronic stress were studied in adult male rats with inherited stress-induced arterial hypertension (ISIAH) and in Wistar rats. Intact males of both rat strains demonstrated a similar behavioural and hormonal activation in sexual arousal. Prepubertal chronic stress decreased the female-induced behavioural response and the effect depended on the character of stress and the animal genotype. No long-lasting effects of pre-pubertal stress on the plasma corticosterone level in males under sexual arousal were observed.

[Serotonin metabolism in the brain during sexual motivation and activation of the murine hypothalamo-hypophyseal-testicular system]. / Metabolizm serotonina v mozge pri polovoi motivatsii i aktivatsii gipotalamo-gipofizarno-semennikovoi sistemy myshei.

Serotonin metabolism was studied in male CBA mice during sexual arousal. It was shown that placement of a receptive female into a cage department separated from a male with a perforated partition, which prevented from the physical contact but allowed a male to see and smell a female, caused an elevation of serotonin metabolism. It was originally shown that 10-min female exposure produced in a male an increase in the level of the main serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA) in the midbrain and its decrease in the hypothalamus. The catabolism coefficient (5-HIAA/serotonin ratio) also increased in the midbrain and decreased in the hypothalamus, while the serotonin content was unchanged. Longer sexual activation of male rats (for 20 min) resulted in an increase in the content of serotonin and 5-HIAA in the amygdala and olfactory bubs, while in the hippocampus only the level of 5-HIAA increased. Thus, for the first time, two stages were distinguished in male sexual arousal. They were determined according to the response of the pituitary-testicular system and involvement of serotonin in different brain regions.

[Serotonin metabolism in the rat brain during water deprivation and hydration]. / Metabolizm serotonina v mozgu pri vodnoi deprivatsii i gidratatsii krys.

Water deprivation (WD) decreased the serotonin (5-HT) level and significantly increased the 5-hydroxyindoleacetic acid (5-HIAA) in the rat midbrain and hypothalamus, the catabolic 5-HIAA/5-HT ratio increasing three-fold. Hydration (H) produced a moderate increase in the 5-HT and 5-HIAA levels in the hypothalamus with no changes in the 5-HIAA/5-HT ratio. Hydration exerted no significant effect upon the 5-HT level and metabolism in the midbrain. A two-fold increase of corticosterone concentration in water deprivation and its decrease in hydration were shown to occur in peripheral blood plasma.

[Characteristics of behavior of knockout mice with genetic monoamine oxidase A deficiency]. / Osobennosti povedeniia myshei s geneticheskim nokautom monoaminoxidazy tipa A.

The effect of deletion of monoamine oxidase A (MAO A) in the gene encoding on behavior of transgenic Tg8 mice was studied. A decrease in the amplitude of acoustic startle reflex rather than the prepulse inhibition was found in lacking MAO A Tg8 mice, as compared with the control C3H strain. The exploratory activity in the hole-board test in Tg8 was decreased as well as the number of crossed lines in the light-dark test. Tg8 mice showed decreased latency and increased intensity of intermale aggression. At the same time, no difference was found between Tg8 and C3H mice in locomotor activity, in the expression of sexual motivation, and in the behavior in the elevated plus-maze test. No predisposition to catalepsy was shown.

[The characteristics of the functional activity of the brain serotoninergic system in the manifestation of natural and pathological anxiety in mice: the effect of the genotype]. / Osobennosti funktsional'noi aktivnosti serotoninergicheskoi sistemy mozga v proiavlenii estestvennoi i patologicheskoi trevozhnosti u myshei: vliianie genotipa.

Anxiety was estimated in intact male mice of C57BL/6J (C57) and (CBA) and CBA/Lac (CBA) strains and in males of both strains after the repeated experience of social defeats (losers) in 10 daily aggressive confrontations. A plus-maze test for behavior in a novel situation and a partition test for communicative activity were applied. Tryptophan hydroxylase (TPH) activity, 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) levels were measured in the midbrain, hypothalamus, amygdala, hippocampus, and striatum in losers and controls (5 days of individual housing of intact animals). Intact C57 mice which demonstrated active avoidance in the maze had reduced TPH activity in the all studied brain regions compared to the intact CBA mice with passive behavior. The 5-HT catabolism in intact C57 was lower in the midbrain and hypothalamus and higher in amygdala, hippocampus, and striatum than in CBA mice. Chronic social stress led to expressed anxiety revealed by both tests in C57 losers in contrast to CBA ones. This anxiety was accompanied by an increase in 5-HIAA level and 5-HIAA/5-HT ratio in the midbrain as well as by an increase in 5-HT level and decrease in 5-HIAA level and 5-HIAA/5-HT ratio in the hippocampus of C57 losers in comparison with the controls. Flesinoxan (0.5 mg/kg, i.p.), 5-HT1A receptor agonist, changed the communicative behavior of controls but was ineffective in losers. Thus, a decrease in sensitivity of 5-HT1A receptors was suggested in stress-induced anxiety of C57 losers. The less expressed anxiety in CBA losers was associated with less expressed changes in serotonergic metabolism. It is concluded that serotonergic mechanisms of pathological anxiety induced by the long-term social stress and those of natural anxiety in intact mice are different.