ABSTRACT
Reciprocal pup substitution (cross-fostering) in cataleptic GC (designated so by the initials of words "genetic" and "catalepsy") and control Wistar females resulted in attenuation of cataleptic predisposition in GC rats fostered by Wistar foster-mothers. The latter demonstrate a more intense maternal care than GC females. There was a significant negative correlation between the frequency of mother staying in nest and the duration of pinch-induced catalepsy in pups fostered by her. In the home-cage retrieval test, the females of the strains compared showed a significant dependence of the latencies of approach to, and retrieval of, pups on their own and the pups' genotype.
Subject(s)
Catalepsy/genetics , Maternal Behavior , Social Environment , Age Factors , Animals , Female , Genetic Predisposition to Disease , Genotype , Rats , Rats, WistarABSTRACT
The effects of thyroidectomy on anxiety-related behavior in the elevated plus-maze test, locomotor activity, and defecation in the open-field test and duration of cataleptic freezing were studied in rats of two strains differing in predisposition to catalepsy: cataleptic strain GC and its ancestor strain Wistar. Total thyroxine level was significantly decreased in control GC rats compared to that in control Wistar rats. Control Wistar and GC rats did not differ either in the percentages of open-arm entries or the time spent therein in the elevated plus-maze test or in defecation score in the open-field test. At the same time, control Wistar rats showed more locomotor activity compared to control GC rats in the open-field test. Thyroid hormone deficiency did not affect the percentages of open-arm entries and the time spent therein in the elevated plus-maze test as well as defecation score in both strains. Thyroidectomy did not alter significantly locomotor activity in Wistar rats, but produced a nearly twofold increase in locomotor activity in GC rats. The most important finding is that thyroidectomy significantly increased the expression of catalepsy in Wistar rats, which points to a role of thyroid hormones in the regulation of predisposition to cataleptic reaction.
Subject(s)
Behavior, Animal/physiology , Catalepsy/physiopathology , Thyroxine/deficiency , Analysis of Variance , Animals , Catalepsy/genetics , Genetic Predisposition to Disease/genetics , Locomotion/physiology , Male , Maze Learning/physiology , Rats , Rats, Mutant Strains , Rats, Wistar , Thyroidectomy , Thyroxine/bloodABSTRACT
Pinch-induced catalepsy was compared at an age of 2 weeks and at weaning in cataleptic GC and control Wistar rats reared by their biological mothers or subjected to reciprocal in-or cross-fostering. Besides, some open-field parameters were studied in the same groups of rats at an age of 2 months. Significant interstrain differences in all the behavioural parameters studied were found. Reciprocal cross-fostering tended to diminish interstrain differences in most parameters. It brought about a decrease of duration of pinch-induced catalepsy at 2 weeks and at weaning in GC rats, and an increase of duration of catalepsy at weaning in Wistar females. Besides, cross-fostering decreased the duration of freezing in the open-field test in GC rats at 2 months.
ABSTRACT
The stereotyped hyperkinesis referred to as pendulum movements (PM) may be found in up to 50% of the animals in stocks of Wistar rats. The mode of inheritance of predisposition to PM was studied by two methods: 1) a classical Mendelian analysis of hybrids of the strains PM+ and PM- bred from Wistar stock for enhancement and absence of PM, respectively, and 2) a segregation analysis of pedigree data from the archive records of breeding the cataleptic GC strain. The two methods gave the same result: the inheritance of predisposition to PM can be explained by a major gene model with an incomplete penetrance of heterozygous genotype.
