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On certain phlo- and ontogenetic correlations in evolution of the central nervous system of vertebrates
686
JOURNAL OF EVOLUTIONARY BIOCHEMISTRY AND PHYSIOLOGY
for a common receptor. Probable factors responsible for seasonal variations in sensitivity of cardiac muscle in this mollusc to acetylcholine, or to stimulation of the visceral ganglion, are discussed.
Changes in functional activity o f the adrenal cortex after denervation: B y T . K . DJARAKIA~: M i l i t a r y M e d i c a l A c a d e m y , L e n i n g r a d , p p . 2 2 1 - 2 2 5 . RmPONSES of denervated adrenals were investigated in rabbits exposed to a 1500 r dose of external whole body irradiation. T h e functional state of adrenal cortex was estimated in terms of its ascorbic acid content. Three months after denervation of an adrenal gland, its ascorbic acid content was not found to differ from that of the intact contralateral gland. One hour after irradiation the amount of ascorbic acid was shown to diminish in both of the adrenals, but more so in the denervated one. T h e effect of stress, like that of exposure to Roentgen rays, on the adrenal cortex is known to be mediated through enhanced pituitary secretion of A C T H . Accordingly, the fact under consideration may be attributed to augmentation of sensitivity to A C T H on the part of the denervated adrenal cortex.
Effect of prolonged growth retardation on age-dependent changes in adrenocortlcotrophic pituitary function and on the response o f adrenals to A C T H : B y L . I. STAVITSKAIA: I n s t i t u t e o f Biology, U n i v e r s i t y , K h a r k o v , pp. 226-232. PROLONGED retardation of growth was induced in albino rats by feeding them a balanced but very low calorie diet. In animals with retarded growth the A C T H content per mg of fresh pituitary gland tissue proved to be raised considerably, as well as A C T H incretion by pituitary in vitro, in each of the age groups studied (3, 12 and 24 months). Age-dependent reduction in A C T H incretion in vitro, characteristic for intact animals, proved to be delayed considerably and less apparent in these animals. It provides evidence of augmented adrenocorticotrophic pituitary function and retardation of its change with age. Investigation of basal corticosteroid incretion by adrenal in vitro and of adrenal response to the addition of two A C T H doses (2 and 4 milliunits) in vitro has revealed basal incretion to be higher, as compared to normal control values, in animals with retarded growth aged 3 months and 12 months. T h e ability of normal adrenals to respond by various rates of augmentation of cortiscosteroid incretion in vitro to the addition of different A C T H doses is lost by 3 months, while adrenals of 12-month-old animals fail to react to any of the A C T H doses tested. When growth had been retarded, this capacity proved to persist up to 12 months of age. It shows adrenocortical function to be raised and its age-linked changes to be restricted in animals with retarded growth.
On certain phylo- and ontogenetic correlations in evolution o f the central nervous system o f vertebrates: By A. I. KARAMmN: I n s t i t u t e o f E v o l u t i o n a r y Physiology and Biochemistry of the Academy of Sciences of the USSR, Leningrad, pp. 233-243. PARTICULAR features of resemblance between structural organization of mature amphibian and reptilian cortex are compared to those of the mammalian cortex at early stages of ontogenesis. It is shown that in amphibia or reptiles, as well as in kittens, evoked potentials
JOURNAL OF EVOLUTIONARY BIOCHEMISTRY AND PHYSIOLOGY
687
(EP) recorded on the first 5 postnatal days are of a similar pattern--surface negativity with long latency (30-100 msec) displaying rapid exhaustion on rhythmical stimulation at 1 c/s frequency. Within a few seconds following application of 0"1% GABA to the cortex of reptilia or kittens, the EP becomes suppressed entirely, tending to recover but slightly, if at all. In the lower vertebrates rhythmical stimulation at 8-12 c/s of various structures of thalamic tegmentum is followed by a recruiting response of the cerebral cortex. On the other hand, stimulation of these structures at higher frequencies, generally resulting in desynchronization in higher vertebrates, is found to bring about only a synchronizing effect in Reptilia and at early stages of ontogenesis in Mammalia. Similarity between early phylogenesis and early ontogenesis has also been found to apply to the phenomenon of postsynaptic facilitation and to the formation of temporary connexions. Strict correlation has been revealed between structural organization of the central nervous system and the main features of temporary connexions. At the earliest stages of phylo- and ontogenesis, temporary connexions of a summational response type may be elaborated. At the next stages, in parallel with specialization occurring in particular regions of the central nervous system, formation of true conditioned reflexes takes place. And, finally, when the neothalamic-neocortical system of integration has arisen and with its progressive development the highest forms of acquired reactions are achieved, assuming the type of associative temporary connexions. These facts are considered with reference to the law of biogenesis or the rule of recapitulation and their applicability to the development of the central nervous system in vertebrates.
Ontogenesis of electrical responses o f cerebral cortex and cerebellum i n M a m m a l i a : By L. S. MUROVA: Institute of E v o l u t i o n a r y Physiology and Bioc h e m i s t r y of the A c a d e m y of Sciences of the U S S R , L e n i n g r a d , pp. 2A,A, 250. EVOLUTIONof spontaneous electrical activity in the sensory-motor cortical zone and cerebellum was studied in kittens aged 1 day to 3 months and in guinea pigs from the first to eighteenth postnatal days. Experiments in guinea pigs included recording of cerebellarevoked potentials (EP) to single or rhythmical stimulation of the sciatic nerve. In the cerebral cortex of 5-7-day-old kittens spontaneous electrical activity represented lowamplitude rhythms up to 15-20 e/s, with occasionally superimposed slower waves. Fast cerebellar activity (300-400 c/s) was recorded in kittens from the seventh to eighth postnatal day. Increasing amplitude and frequency of the slow waves in the EEG of kittens resulted in the appearance of an alpha-like type of activity., becoming continuous and prevalent from 10-day age. By the end of the first postnatal month of kittens, spontaneous electrical activity both in cerebral cortex (6-11 c/s, 150-250 mV) and cerebellum (400-450 c/s, 25-30 mV) tended to assume characteristics of activity inherent to adult animals. In contrast to kittens, guinea pigs were found to display patterned rhythmical activity both in cerebral cortex and cerebellum recorded from the first postnatal day. Responses were similar to those of adult animals, being reproduced at relatively high rates (up to 10 c/s) of stimulation.
Elaboration o f primary (postsynaptic) inhibition with postnatal ontogenesis in the cat: By N. M . JAKOVLEV: Institute of E x p e r i m e n t a l M e d i c i n e of the A c a d e m y of Medical Sciences of the U S S R , L e n i n g r a d , pp. 251-256. A PAIRRDstimuli technique has been used in decapitated kittens of different ages (from a few hours to 34 days). Effective postsynaptic inhibition has been found to appear by the
JOURNAL OF EVOLUTIONARY BIOCHEMISTRY AND PHYSIOLOGY
for a common receptor. Probable factors responsible for seasonal variations in sensitivity of cardiac muscle in this mollusc to acetylcholine, or to stimulation of the visceral ganglion, are discussed.
Changes in functional activity o f the adrenal cortex after denervation: B y T . K . DJARAKIA~: M i l i t a r y M e d i c a l A c a d e m y , L e n i n g r a d , p p . 2 2 1 - 2 2 5 . RmPONSES of denervated adrenals were investigated in rabbits exposed to a 1500 r dose of external whole body irradiation. T h e functional state of adrenal cortex was estimated in terms of its ascorbic acid content. Three months after denervation of an adrenal gland, its ascorbic acid content was not found to differ from that of the intact contralateral gland. One hour after irradiation the amount of ascorbic acid was shown to diminish in both of the adrenals, but more so in the denervated one. T h e effect of stress, like that of exposure to Roentgen rays, on the adrenal cortex is known to be mediated through enhanced pituitary secretion of A C T H . Accordingly, the fact under consideration may be attributed to augmentation of sensitivity to A C T H on the part of the denervated adrenal cortex.
Effect of prolonged growth retardation on age-dependent changes in adrenocortlcotrophic pituitary function and on the response o f adrenals to A C T H : B y L . I. STAVITSKAIA: I n s t i t u t e o f Biology, U n i v e r s i t y , K h a r k o v , pp. 226-232. PROLONGED retardation of growth was induced in albino rats by feeding them a balanced but very low calorie diet. In animals with retarded growth the A C T H content per mg of fresh pituitary gland tissue proved to be raised considerably, as well as A C T H incretion by pituitary in vitro, in each of the age groups studied (3, 12 and 24 months). Age-dependent reduction in A C T H incretion in vitro, characteristic for intact animals, proved to be delayed considerably and less apparent in these animals. It provides evidence of augmented adrenocorticotrophic pituitary function and retardation of its change with age. Investigation of basal corticosteroid incretion by adrenal in vitro and of adrenal response to the addition of two A C T H doses (2 and 4 milliunits) in vitro has revealed basal incretion to be higher, as compared to normal control values, in animals with retarded growth aged 3 months and 12 months. T h e ability of normal adrenals to respond by various rates of augmentation of cortiscosteroid incretion in vitro to the addition of different A C T H doses is lost by 3 months, while adrenals of 12-month-old animals fail to react to any of the A C T H doses tested. When growth had been retarded, this capacity proved to persist up to 12 months of age. It shows adrenocortical function to be raised and its age-linked changes to be restricted in animals with retarded growth.
On certain phylo- and ontogenetic correlations in evolution o f the central nervous system o f vertebrates: By A. I. KARAMmN: I n s t i t u t e o f E v o l u t i o n a r y Physiology and Biochemistry of the Academy of Sciences of the USSR, Leningrad, pp. 233-243. PARTICULAR features of resemblance between structural organization of mature amphibian and reptilian cortex are compared to those of the mammalian cortex at early stages of ontogenesis. It is shown that in amphibia or reptiles, as well as in kittens, evoked potentials
JOURNAL OF EVOLUTIONARY BIOCHEMISTRY AND PHYSIOLOGY
687
(EP) recorded on the first 5 postnatal days are of a similar pattern--surface negativity with long latency (30-100 msec) displaying rapid exhaustion on rhythmical stimulation at 1 c/s frequency. Within a few seconds following application of 0"1% GABA to the cortex of reptilia or kittens, the EP becomes suppressed entirely, tending to recover but slightly, if at all. In the lower vertebrates rhythmical stimulation at 8-12 c/s of various structures of thalamic tegmentum is followed by a recruiting response of the cerebral cortex. On the other hand, stimulation of these structures at higher frequencies, generally resulting in desynchronization in higher vertebrates, is found to bring about only a synchronizing effect in Reptilia and at early stages of ontogenesis in Mammalia. Similarity between early phylogenesis and early ontogenesis has also been found to apply to the phenomenon of postsynaptic facilitation and to the formation of temporary connexions. Strict correlation has been revealed between structural organization of the central nervous system and the main features of temporary connexions. At the earliest stages of phylo- and ontogenesis, temporary connexions of a summational response type may be elaborated. At the next stages, in parallel with specialization occurring in particular regions of the central nervous system, formation of true conditioned reflexes takes place. And, finally, when the neothalamic-neocortical system of integration has arisen and with its progressive development the highest forms of acquired reactions are achieved, assuming the type of associative temporary connexions. These facts are considered with reference to the law of biogenesis or the rule of recapitulation and their applicability to the development of the central nervous system in vertebrates.
Ontogenesis of electrical responses o f cerebral cortex and cerebellum i n M a m m a l i a : By L. S. MUROVA: Institute of E v o l u t i o n a r y Physiology and Bioc h e m i s t r y of the A c a d e m y of Sciences of the U S S R , L e n i n g r a d , pp. 2A,A, 250. EVOLUTIONof spontaneous electrical activity in the sensory-motor cortical zone and cerebellum was studied in kittens aged 1 day to 3 months and in guinea pigs from the first to eighteenth postnatal days. Experiments in guinea pigs included recording of cerebellarevoked potentials (EP) to single or rhythmical stimulation of the sciatic nerve. In the cerebral cortex of 5-7-day-old kittens spontaneous electrical activity represented lowamplitude rhythms up to 15-20 e/s, with occasionally superimposed slower waves. Fast cerebellar activity (300-400 c/s) was recorded in kittens from the seventh to eighth postnatal day. Increasing amplitude and frequency of the slow waves in the EEG of kittens resulted in the appearance of an alpha-like type of activity., becoming continuous and prevalent from 10-day age. By the end of the first postnatal month of kittens, spontaneous electrical activity both in cerebral cortex (6-11 c/s, 150-250 mV) and cerebellum (400-450 c/s, 25-30 mV) tended to assume characteristics of activity inherent to adult animals. In contrast to kittens, guinea pigs were found to display patterned rhythmical activity both in cerebral cortex and cerebellum recorded from the first postnatal day. Responses were similar to those of adult animals, being reproduced at relatively high rates (up to 10 c/s) of stimulation.
Elaboration o f primary (postsynaptic) inhibition with postnatal ontogenesis in the cat: By N. M . JAKOVLEV: Institute of E x p e r i m e n t a l M e d i c i n e of the A c a d e m y of Medical Sciences of the U S S R , L e n i n g r a d , pp. 251-256. A PAIRRDstimuli technique has been used in decapitated kittens of different ages (from a few hours to 34 days). Effective postsynaptic inhibition has been found to appear by the