Social behavior and spatial orientation in rat strains with genetic predisposition to catatonia (GC) and stereotypes (PM).

Various psychopathologies, including schizophrenia, bipolar disorder and major depression, are associated with abnormalities in social behavior and learning. One of the syndromes that may also take place in these disorders is catatonia. Catatonia is a psychomotor syndrome in which motor excitement, stereotypy, stuporous state, including the phenomenon of "waxy flexibility" (catalepsy), can be observed. Rats with genetic catatonia (GC) and pendulum-like movements (PM) of the anterior half of the body have physiological and behavioral changes similar to those observed in schizophrenia and depression in humans and can be considered as incomplete experimental models of these pathologies. The social behavior of the GC and PM rats has not been previously studied, and the cognitive abilities of animals of these strains are also insufficiently studied. To determine whether the GC and PM rats have changes in social behavior and spatial learning, behavioral phenotyping was performed in the resident-intruder test, three-chamber test, Barnes maze test. Some deviations in social behavior, such as increased offensive aggression in PM rats in the resident-intruder test, increased or decreased social interactions depending on the environment in different tests in GC, were shown. In addition, principal component analysis revealed a negative association between catatonic freezing and the socialization index in the three-chamber test. Decreased locomotor activity of GС rats can adversely affect the performance of tasks on spatial memory. It has been shown that PM rats do not use a spatial strategy in the Barnes maze, which may indicate impairment of learning and spatial memory.

[EFFECTS OF IN VITRO CULTURE AND EMBRYO TRANSFER ON THE ARTERIAL BLOOD PRESSURE, BODY WEIGHT AND BEHAVIOUR IN ISIAH RATS].

This study was the first to investigate long-term effects of in vitro culturing of embryos combined with their cryopreservation and transfer on arterial blood pressure, body weight and behavior in hypertensive rats. No differences in body weight and arterial blood pressure levels were found between the naturally born rats and those born with the help of ART (assisted reproductive technologies). However, ART-born rats spent more time on rearing, as was revealed by the open-field test. The results of the elevated plus maze test indicated that these rats spent more time in the open arms and demonstrated a longer duration of head dips. Moreover, the light-dark box test showed a longer total leaning-out time in this group. Taken together, the results of the three behavioral tests demonstrate a greater exploratory activity and lower anxiety in ART-born ISIAH rats than in natural born ones.

Synchronization of the Estrous Cycle against the Background of Increased Excitability in Rats Selected for Catatonic Type of Reaction.

Selection for the elevation of catatonic type of reaction in female GC rats ("genetic" and "catatonia") was followed by an increase in the number of intense running episodes in response to acoustic stimulation. The observed changes are typical of increased general excitability in these animals. The phenomenon of estrous cycle synchronization was confirmed by variations in the concentrations of estradiol and progesterone in groups of Wistar and GC rats differing by the degree of synchronization. Some differences were found in the concentration of main sex hormones in the blood from female GC and Wistar rats.

[Selection for catatonic reaction in rats: a study of interstrain differences by magnetic resonance imaging].

Brain studies by magnetic resonance imaging, angiography, and spectroscopy have been performed with rat strains Wistar, GC (genetic and catatonia), and PM+ (pendulum movements). Both GC and PM+ rats show similar deviations from the ancestral Wistar population in having smaller areas of the right striatum (coronal slice). The anterior horns of lateral ventricles in GC rats are smaller than in the control strain. The maximum blood flow velocity in the common carotid arteries of PM+ rats is greater. The GC and PM+ strains differ in myo-inositol level in the hippocampus. The PM+ strain is characterized by a lower taurine level in the hippocampus, which may be one of the participants regulated the predisposition to audiogenic seizures.

[The increase in the proportion of nervous animals bred for catatonia: the participation of central adrenoreceptors in catatonic reactions].

Using a large amount of breeding material, the idea of D. K. Belyaev on the role of selection in the appearance of new behavioral and neuronal forms was confirmed. Experiments were performed using rats of the GC (genetics + catatonia) strain, which are prone to passive defensive reactions of cataleptic freezing. At the current breeding stage, elevation of the proportion of so-called nervous animals was demonstrated, both with respect to the expression of such reactions and their frequency. At this breeding stage, in the brains of GC rats, the mRNA levels of alpha1A- and alpha2A-adrenoreceptor genes were determined. A decrease of alpha1A-adrenoreceptor gene expression in the midbrain and medulla oblongata, along with elevation of alpha2A-adrenoreceptor gene expression in the frontal cortex was observed. It was suggested that changes in the expression of alpha-adrenoreceptor genes could be caused by an increase in the proportion of nervous animals and could contribute to the akinetic behavioral component in GC rats.

Age-specific features of estrous cycles and folliculogenesis in GC female rats selected by catatonic reactivity.

A decrease in the total count of follicles in the diestrus and proestrus and higher incidence of permanent estruses were found in 3-month-old females of the catatonic GC rat strain in comparison with Wistar females (control). At the age of 6-12 months, GC females had lower incidence of long estrus and diestrus. The estrous cycle of GC females was shorter than of Wistar rats. With aging (at the age of 18 months), the counts of growing and maturing follicles significantly decreased. Higher counts of growing single-layer and bilayer follicles were found in 18-month-old GC females. Differences in the length of estrus and diestrus and in the incidence of abnormal phases in the two strains also disappeared at this age. Selection by high catatonic reactivity was associated with a decrease in body weight.

[Confirmation of a positive genetic relationship between pendulum movements, audiogenic epilepsy, catalepsy, and "nervousness" in rats].

Relationships between the predispositions to pendulum movements (PMs), catalepsy, and audiogenic epilepsy in the course of breeding for "nervousness" and freezing have been studied. A positive genetic relationship between PMs, catalepsy, and audiogenic epilepsy has been demonstrated. Eighty to ninety percent of rats selected for enhanced PMs (strain PM+) exhibit predisposition to audiogenic seizures, whereas this frequency in the PM-free strain (PM-) is 10-40%.

[Typological characteristics of behavior in strains of rats bred for enhancement and absence of pendulum movements. Association with brain monoamines].

Typological characteristics of behavior were studied in rats bred for enhancement (PM+) and absence (PM-) of pendulum movements. Excitement in different test situations was manifest in PM+ rats, whereas passive defensive reactions were characteristic of PM- rats. Increased excitability of PM+ rats was expressed in their greater predisposition to audiogenic epilepsy (83% in PM+ versus 40% in PM- rats). On the contrary, PM- rats were found to be more prone to freezing (61% in PV- versus 11% in PM+). In PM+ rats, noradrenaline and serotonin contents were decreased in hypothalamus (as compared to PM- and control Wistar stain), whereas in PM- rats, serotonin content was increased in striatum, hypothalamus and midbrain as compared to control strains.

[Some neuroendocrinological changes in rats of cataleptic strain GC. Influences of ontogenesis and generation of breeding].

The content of biogenic amines: dopamine, noradrenaline and serotonine, in rats of cataleptic strain GC as compared with the control strain Wistar at the age of 1 and 5 months is decreased, the maximal decrease being found in the so-called "nervous" animals. The aldosterone content was decreased at 5 month age in the GC rats. The testosterone content at the age of 1 month in GC rats does not differ from that in Wistar rats, but at the age of 5 months it was decreased as compared to Wistar, the maximal decrease being found again in "nervous" GC rats. The data obtained point to peculiarities of ontogenetic regulation and to commonness of mechanisms of catalepsy and "nervousness" in GC rats.

[Dual manifestation of catatonic reaction in rats].

Results of genetic, neurophysiological, neurochemical and pharmacological suggest that the cataleptic freezing and "nervousness" observed in the cataleptic rat strain GC have a common mechanism. There seems to be a physiological factor causing catalepsy, upon reaching a certain level of intensity, to be transformed into "nervousness", which is observed both at different period and/or moment of individual life and in the processes of breeding the strain for predisposition to catalepsy.