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PubMed1997

[Toxicity studies of landiolol hydrochloride (ONO-1101) (2). 4-week repeated dose intravenous toxicity study in rats with 4-week recovery test].

4-week repeated dose toxicity study with 4-week recovery test of landiolol hydrochloride (ONO-1101), a novel ultra short acting beta-blocker, was conducted in Sprague-Dawley (SD) rats. ONO-1101 was administered intravenously to rats of both sexes at a dose level of 0 (control), 12.5, 25, 50 or 100 mg/kg/day. In the 100 mg/kg/day group, bradypnea or dyspnea was seen in all animals, pale in ear, eye and foot, tremor, reddish lacrimation and loss of righting reflex were also observed in some animals right after administration, and then those signs disappeared within 1 min after administration. During the treatment period, 3/20 animals of each sex in the 100 mg/kg/day showed clonic convulsion and died within 2 min after administration. No clinical changes were seen in the 50 mg/kg/day group or lower. Histopathological findings showed atrophy of the submaxillary gland in females and vessel-wall thickening and perivascular fibrosis of the injection site (tail) in both sexes at 100 mg/kg/day, however those changes were reversible. ONO-1101 did not effect on body weight, food consumption, ophthalmology, urinalysis, hematology, blood chemistry, organ weights or necropsy at any doses. These results indicate that the no-adverse-effect level of ONO-1101 in rats is 50 mg/kg/day for both sexes in this study.

Adrenergic beta-Antagonists↗

PubMedDate not supplied

[Neonatal reflexes variability in the normal full term neonate during the neurological exam].

It has been stated that findings in neonatal neurological examinations can play a role as a pointer to adverse developmental outcome. The description of the examinations, and their presence or absence differed among authors without clear reference to their physiological variability ranges. We approached the study of some neonatal behaviours and reflexes in 143 examinations made on 113 healthy newborn babies from the maternity wards by looking at the influence that perinatal environmental factors which are considered normal, can play in these examinations. The results showed that the flexion answer of the Babinski reflex increased significantly between the first and third day of life (c2= 4.4478; p= 0.03495) in the same way there was an increase in the stepping reflex (c2= 3.999; p= 0.04552) in the righting reflex (c2= 4.9342; p= 0.02633) and in the supporting reaction (c2= 11.7874; p= 0.0006). This was significantly reduced in the caesarean section deliveries (c2= 7.1209; p= 0.0076). Head reaction was only detectable during the Brazelton behavioural states 1 to 3 (c2= 3.8911; p= 0.04854) and the same thing happened with the stepping reflex (c2= 4.9370; p= 0.02629). We discuss the utility of neonatal reflexes scoring scales in predicting the neurodevelopmental outcome of the newborn baby.

Female↗

PubMed1982

Comparison of unconditioned reflex and conditioned avoidance tests in rats exposed by inhalation to carbon monoxide, 1,1,1-trichloroethane, toluene or ethanol.

The sensitivity of unconditioned reflex and conditioned avoidance tests in evaluating behavioral toxicity was compared. Male rats were exposed by inhalation up to four hours to 0, 200, 400, 800 or 1600 ppm carbon monoxide (CO); 0, 1500, 3000, 6000 or 12,000 ppm 1,1,1-trichloroethane; 0, 800, 1600, 3200, or 6400 ppm toluene; or 0, 4000, 8000, 16,000 or 32,000 ppm ethanol. Animals were tested for behavioral changes at one-half, one, two and four hours during exposure and eighteen hours after exposure ended. In unconditioned reflex testing the presence or absence of specific unconditioned reflexes (such as corneal, placing, grasping and righting reflexes) and simple behavior patterns including locomotor activity and coordination were observed. The conditioned reflex task consisted of shock avoidance by lever press following simultaneous light and sound stimuli. Rats began to fail unconditioned reflex tests at 800 ppm CO, 3000 ppm trichloroethane, 800 ppm toluene and 8000 ppm ethanol. Decrements in conditioned avoidance were observed at 800 ppm CO, 6000 ppm trichloroethane, 3200 ppm toluene and 8000 ppm ethanol. Neither test was consistently more sensitive than the other in detecting behavioral changes. For both methods, the concentrations at which changes were detected in rats were two to tenfold higher than those reported for human effects.

Animals↗

PubMedDate not supplied

Grasp-reflex strength from right and left hands in relation to serum cortisol level and fetal position in human neonates.

The grasp-reflex strengths from right (R) and left (L) hands were studied in human neonates in relation to serum cortisol levels and fetal position. In males with right-ear out, there was no correlation between grasp-reflex strength from right hand and cortisol. The grasp-reflex strength from left hand significantly decreased as cortisol increased linearly in these subjects. In males with left-ear out, the grasp-reflex strengths from right and left hands were found to be negatively linearly correlated with serum cortisol level. In females with right-ear out, the grasp-reflex strength from right hand was not significantly correlated with cortisol, but grasp reflex from left hand linearly decreased as cortisol increased. In females with left-ear out, only the grasp reflex from right hand linearly increased with cortisol. Only in males with right-ear out, the R-L grasp-reflex strength linearly increased from left dominance toward right dominance. It was concluded that the stress hormone cortisol may be disadvantageous and/or advantageous for the prenatal development of the right and left brain according to fetal position; cortisol may also affect the emergence of cerebral lateralization.

Embryonic and Fetal Development↗

PubMed1992

Effects of exposure of pregnant mice to chlordiazepoxide (CDP) on the development and ultrasound production of their offspring.

1. The effects were studied of injecting pregnant Alderley Park mice with the benzodiazepine agonist chlordiazepoxide (CDP) at doses of 10 and 30 mg/kg during the last 9-10 days of gestation on the early behaviour and development of their offspring. 2. All neonates were fostered to non-treated lactating dams to eliminate maternally-mediated effects. 3. Early development and responses to anxiety-related situations were studied by recording body growth, righting reflex, rooting behaviour, cliff avoidance reflex and ultrasonic "distress" calling. 4. Drug treatment: (a) retarded postnatal body growth; (b) delayed the righting and cliff avoidance reflexes; (c) augmented rooting behaviour and (d) produced an overall increase in ultrasonic calling (but with the higher dose decreasing emission on days 1-2). 5. Exposure to CDP during foetal life retards motor development and physical maturation; produces a sedative/anxiolytic action (especially at high doses) and may modify the sensitivity of GABA-BZP receptor complex to endogenous receptor ligands.

Analysis of Variance↗

PubMed1985

[General pharmacologic studies on the analgesic flupirtine].

In the present study the general pharmacological properties of ethyl-N-[2-amino-6-(4-fluor-phenylmethylamino)pyridin-3-yl]carbama te (flupirtine, D 9998), a structural new analgesic, are described. In several tests with mice flupirtine shows a centrally depressant component of action. However, regarding undesirable side effects as ataxia, inhibition of motor activity etc. this action is, with respect to the analgesic effective doses less pronounced than those of comparable analgesics, for instance phenacetin. In relatively low doses flupirtine antagonizes tremor induced by oxotremorine in mice. This activity is probably not caused by a central anticholinergic action, because other anticholinergic effects have not been observed. It should be pointed out that flupirtine antagonizes the morphine-induced tail phenomenon in mice in relatively low doses. This action obviously differentiates flupirtine from opiates. Up to high doses flupirtine does not cause catalepsia in mice, consequently its centrally depressant activity does not resemble that of reserpine and also is not comparable with those of neuroleptic agents. The corneal and pinnal reflexes are not influenced by flupirtine and the righting reflex is slightly delayed in high doses. The anticonvulsive activity of flupirtine observed in the pentetrazol shock test (mouse) after high doses probably cannot be considered to occur within the analgesic dose range. Inhibition of amphetamine toxicity in mice observed in doses near the hypnotic doses may be caused by non-specific effects. In vitro tests with isolated trachea or ileum of guinea pigs show that flupirtine possesses no or very weak antagonism against histamine-induced spasms. In spasms caused by barium chloride flupirtine shows a weak musculotropic-spasmolytic activity. Investigations on the circulatory system of dogs do not indicate any incompatibilities with flupirtine. No evidence of antiarrhythmic activity was found in rats. Flupirtine has no local anesthetic activity in mice but some weak effects on the cornea of rabbits. Like several other analgesics flupirtine shows in rats a reversible antidiuretic action including sodium and chloride retention which is of relatively short duration and is not observed in long-term studies in rats and dogs. In contrast to many stronger antiinflammatory compounds, flupirtine does not possess ulcerogenic activity in rats up to high doses. A minimal inhibition of intestinal motility (mouse) is observed only in doses higher than the analgesic effective doses.

Aminopyridines↗

PubMed2005

Volatile anesthetics enhance flash-induced gamma oscillations in rat visual cortex.

BACKGROUND: The authors sought to understand neural correlates of anesthetic-induced unconsciousness. Cortical gamma oscillations have been associated with neural processes supporting conscious perception, but the effect of general anesthesia on these oscillations is controversial. In this study, the authors examined three volatile anesthetics, halothane, isoflurane, and desflurane, and compared their effects on flash-induced gamma oscillations in terms of equivalent concentrations producing the loss of righting reflex (1 minimum alveolar concentration for the loss of righting [MAC(LR)]). METHODS: Light flashes were presented every 5 s for 5 min, and event-related potentials were recorded from primary visual cortex of 15 rats with a chronically implanted bipolar electrode at increasing anesthetic concentrations (0-2.4 MAC(LR)). Early cortical response was obtained by averaging poststimulus (0-100 ms) potentials filtered at 20-60 Hz across 60 trials. Late (100-1,000 ms) gamma power was calculated using multitaper power spectral technique. Wavelet decomposition was used to determine spectral and temporal distributions of gamma power. RESULTS: The authors found that (1) halothane, isoflurane, and desflurane enhanced the flash-evoked early cortical response in a concentration-dependent manner; (2) the effective concentration for this enhancement was the lowest for isoflurane, intermediate for halothane, and the highest for desflurane when compared at equal fractions of the concentration that led to a loss of righting; (3) the power of flash-induced late (> 100 ms) gamma oscillations was augmented at intermediate concentrations of all three anesthetic agents; and (4) flash-induced gamma power was not reduced below waking baseline even in deep anesthesia. CONCLUSIONS: These findings suggest that a reduction in flash-induced gamma oscillations in rat visual cortex is not a unitary correlate of anesthetic-induced unconsciousness.

Anesthetics, Inhalation↗

PubMed1978

Methylazoxymethanol acetate: effect of postnatal injection on brain amines and behavior.

The antimitotic drug, methylazoxymethanol acetate (MAMA), was injected into newborn rats during the first four days of life. At 48 days of age, these rats weighed one-third less than controls, as did the cerebella of their brains, but the rest of their brains weighed only 7% less than those of controls. The cerebella structures of the drug-injected rats was highly disorganized. Purkinje cells were scattered haphazardly in the granular layer instead of forming a monolayer. More foldings and short folia were found in the cerebella of drugged animals. In spite of these large morphological differences, the total amounts of norepinephrine and serotonin in the cerebella of the drugged rats were not different from those of the control rats. Behavioral effects of postnatal injection of MAMA include retarded development of the righting reflex,i.e., the drugged pups took longer time to right themselves when placed on their backs during the first nine days after birth; and scondly, MAMA reduced locomotor activity measured 45 days after birth.

Animals↗

PubMed2003

Motor disturbances in mice with deficiency of the sodium channel gene Scn8a show features of human dystonia.

The med(J) mouse with twisting movements related to deficiency of the sodium channel Scn8a has been proposed as a model of kinesiogenic dystonia. This prompted us to examine the phenotype of these mice in more detail. By cortical electroencephalographic (EEG) recordings, we could not detect any changes, demonstrating that the motor disturbances are not epileptic in nature, an important similarity to human dystonia. The significantly decreased body weight of med(J) mice was related to reduced food intake. Observations in the open field and by video recordings revealed that the mice exhibit sustained abnormal postures and movements of limbs, trunk and tail not only during locomotor activity but also at rest. With the exception of the head tremor, the other motor impairments were persistent rather than paroxysmal. When several neurological reflexes were tested, alterations were restricted to the posture and righting reflexes. Results of the wire hang test confirmed the greatly reduced muscle strength in the med(J) mouse. In agreement with different types of human dystonia, biperiden, haloperidol and diazepam moderately reduced the severity of motor disturbances in med(J) mice. In view of the sodium channel deficiency in med(J) mice, the beneficial effects of the sodium channel blocker phenytoin was an unexpected finding. By immunohistochemical examinations, the density of nigral dopaminergic neurons was found to be unaltered, substantiating the absence of pathomorphological abnormalities within the brain of med(J) mice shown by previous studies. With the exception of muscle weakness, many of the features of the med(J) mouse are similar to human idiopathic dystonia.

Animals↗

PubMedDate not supplied

Effect of low protein diet on manganese neurotoxicity: I. Developmental and biochemical changes.

The first in a series of studies on the effect of concurrent low protein diet (10% casein) and manganese exposure (Mn2+, 3 mg/ml drinking water) in rats is reported here. The effect on growing (Fo-90 days) rehabilitated (Fo low leads to normal protein diet-28 days) and the F1 generation pups (weaned) were studied. Mn2+ exposure had no significant effect on growth pattern, brain weight or brain and plasma protein contents in either dietary groups. The diet regimen had no significant effect on the accumulation of Mn2+ in brain in any of the groups studied but the levels were higher in the F1 pups than in the parent (Fo) generation. In the F1 pups Mn2+ exposure had no effect on eye opening in either dietary group, delayed the development of startle reflex in low protein fed group only but the air righting reflex development was delayed in both the dietary groups, the effect being more marked in the low protein fed group. These changes reflect the early neurotoxic effect of Mn2+.

Animals↗

PubMed1991

The relationship of latency characteristics of the Hoffmann reflex from the right and left thenar muscles to serum testosterone levels in right-handed male and female subjects.

The latency characteristics of the Hoffmann reflex from the right and left thenar muscles were analyzed in right-handed young men and women relative to serum testosterone levels. There was no correlation between the H-reflex latencies and serum testosterone levels in the female subjects. In the male subjects, the H-reflex latencies from the right and left sides were found to be negatively linearly related to the serum testosterone levels. The right minus left latencies were found to be inversely correlated with serum testosterone levels in women; there was no correlation between these variables in men. It was also established that the right-left differences in the H-reflex latencies were directly related to the degree of the right-hand preference in the female subjects. It was concluded that testosterone may, at least, contribute to the spinal-motor lateralization in women, but not in men. The results were also discussed with regard to the testosterone hypothesis of cerebral lateralization, sex-related differences, hand preference, hand skill, and intelligence.

Adult↗

PubMed2006

Effects of combining ethanol (EtOH) with gamma-hydroxybutyrate (GHB) on the discriminative stimulus, locomotor, and motor-impairing functions of GHB in mice.

RATIONALE: Gamma-hydroxybutyrate (GHB) is a drug of abuse that is often coabused with ethanol (EtOH) and has been implicated as a date rape agent in conjunction with EtOH. Much information is lacking regarding the manner in which GHB interacts with EtOH. OBJECTIVE: This study was designed to further characterize the behavioral effects of GHB alone and in combination with EtOH in male Swiss-Webster mice. METHODS: The effects of GHB (0.1-1.0 g/kg) and EtOH (2.0-5.0 g/kg) alone, as well as the effects of GHB in combination with EtOH, were examined using an automated locomotor activity procedure, a functional observational battery (FOB) and a GHB drug discrimination procedure. RESULTS: GHB decreased, whereas EtOH had little effect on locomotor activity. In the FOB, EtOH dose-dependently decreased activity in combination with 0.3 g/kg GHB. Alone, each drug had little effect on the righting reflex, but combining ineffective doses of GHB and EtOH significantly impaired righting. GHB and EtOH decreased forelimb grip strength. Combinations of ineffective doses of GHB and EtOH decreased forelimb grip strength when given together. GHB and EtOH impaired inverted screen performance, and EtOH increased the impairing effects of low, but not high, doses of GHB. GHB and EtOH increased hind limb splay, and EtOH increased the effects of 0.1 and 0.3 g/kg GHB on splay. GHB and EtOH decreased body temperature, and EtOH augmented the temperature-decreasing effects of GHB. EtOH produced less than 50% GHB-like discriminative stimulus effects, and GHB failed to alter the GHB-like discriminative stimulus effects of EtOH. CONCLUSIONS: Overall, EtOH increased the effects of GHB on several gross measures of behavior and only partially occasioned the discriminative stimulus properties of GHB.

Animals↗

PubMed1998

Genetic mapping of a locus (mass1) causing audiogenic seizures in mice.

Frings audiogenic seizure-susceptible mice are a model for sensory-evoked reflex seizures. Their seizure phenotype is characterized by wild running, loss of righting reflex, tonic flexion, and tonic extension in response to high-intensity sound stimulation. The Frings mice represent an inbred colony that has not been genetically characterized. This investigation studied the mode of inheritance for audiogenic seizures by crossing the Frings mouse with the seizure-resistant C57BL/6J mouse. Among the backcross progeny generated by crossing (Frings x C57BL/6J)F1 mice with the Frings strain, 391 of the 836 N2 progeny were audiogenic seizure susceptible, a finding consistent with monogenic inheritance. Genetic mapping and linkage analysis of hybrid mice using MIT microsatellite marker sequences localized the seizure gene, named mass1 for monogenic audiogenic seizure susceptible, to an approximately 3.6 cM interval in the middle of mouse chromosome 13. Linkage of mass1 to chromosome 13 is an important step in identifying the gene associated with a monogenic seizure disorder in mice, which may ultimately lead to a better understanding of the pathophysiology of human seizure disorders.

Acoustic Stimulation↗

PubMed1999

Behaviour of adult hamsters subjected to hypergravity.

We studied vestibular function in 20 adult hamsters (3 months old) subjected to either prolonged hypergravity (n = 10) or normal gravity (n = 10) for 2 months. Locomotion and swimming of the hypergravity hamsters under light conditions were normal. Equilibrium maintenance was severely disturbed; only 6 of 10 hypergravity hamsters managed to walk on the small tube after 2 months, whereas all 10 controls were able to walk on the tube. The air-righting reflex was severely disturbed; the hypergravity hamsters made 30% correct air-righting responses, while the control hamsters made 88% correct responses. Finally, 5 of 8 hypergravity hamsters had to be saved from drowning when swimming in total darkness. Histological examination of the utricular otoconial layers afterwards, using energy dispersive X-ray element (EDAX) analysis and scanning electron microscopy, did not reveal any differences in calcium content, shape and size distribution of the otoconia between hypergravity hamsters and controls. We suggest that adult hamsters adapt to hypergravity, leading to problems in normal functioning when tested in 1 G, especially in tasks in which sensory input of the vestibular system is important for spatial orientation. These disturbances were more severe in adult hamsters than in young ones, tested in previous experiments. Therefore, we assume that age is a factor for adaptation to altered gravity conditions.

Adaptation, Physiological↗

PubMed2003

Dissociation between electrical and mechanical bulbocavernosus reflexes.

AIMS: To record reflex motor responses, elicited by mechanical stimulation of the penis or clitoris, in each bulbocavernosus muscles and to compare left and right reflex pathways in normal subjects, then to compare electrical and mechanical responses in various neurological diseases. METHODS: Two groups of patients were studied: 22 patients without neurological disease considered as normal subjects; and 25 patients with neurological disease (three multiple sclerosis, six spina bifida, nine conus medullaris syndrome, three peripheral neuropathies, two lumbosacral lesions, one multisystem atrophy, and one syringomyelia). Electrical bulbocavernosus reflex (EBCR) was evoked by orthodromic stimulation of the dorsal nerve of the penis at the penile base or the clitoris. Mechanical bulbocavernosus reflex (MBCR) was elicited with an electromechanical hammer, tapping directly on the clitoris zone or on the ventral part of glans penis. For EBCR and MBCR, bulbocavernosus muscle contractions were successively recorded in the left and in the right side with a needle inserted under visual guidance. RESULTS: Mean left mechanical latency was 31.7 msec (SD = 4.5) and right one 31.6 msec (SD = 3.8). The reproducibility of the responses was excellent (P < 0.0001). ). The mean difference between left and right latencies was 2 msec (SD = 1.2). In the neurological group, 22 EBCR (six right, nine left, seven bilateral) and 19 MBCR (eight right, nine left, two bilateral) were considered abnormal. The mean reflex latencies in patients with neurological lesions (lower motor neuron lesions) were statistically longer (P < 0.0001) than in normal subjects. Exact concordance (side of lesion) between MBCR and EBCR was observed in 15/25 cases (60%), poor concordance (presence of a sacral reflex alteration) in 3/25 (12%) cases, and in 7/25 (28%) cases there was a significant difference between the two techniques. CONCLUSIONS: MBCR may provide a good alternative for electrical stimulation and can be used to evaluate urinary disorders when a neurological etiology is suspected. However, the presence of false negatives with MBCR suggest that it may be more useful as a screening test.

Clitoris↗

PubMed1991

Comparison of the behavioral teratogenic potential of phenytoin, mephenytoin, ethotoin, and hydantoin in rats.

Pregnant Sprague-Dawley CD rats were orally administered either phenytoin (PHT, 200 mg/kg), mephenytoin (MPH, 100 mg/kg), ethotoin (ETH, 600 mg/kg), hydantoin (HYD, 1,200 mg/kg) or vehicle (propylene glycol) on days 7-18 of gestation. Mean (+/- S.E.) maternal serum concentrations of PHT, MPH, and ETH 1 hour after dosing on gestational day 18 were 16.0 +/- 3.3, 10.7 +/- 3.0, and 65.2 +/- 10.45, respectively, and free fractions were 16%, 18%, and 11% respectively. The free fraction for PHT is similar, but was lower for both MPH and ETH than that seen in humans. Preweaning mortality for PHT, MPH, ETH, HYD, and controls was 25%, 6.3%, 12.5%, 2.0% and 0.8%, respectively. The MPH and ETH-exposed animals weighed approximately 6.6% less than controls throughout the study; the other groups did not differ significantly. PHT offspring showed increased early locomotor activity. Only PHT-exposed animals (27%) exhibited abnormal circling behavior after weaning. PHT-circlers accounted for higher levels of activity in an open-field test and for longer straight channel swimming times. PHT-circlers and noncirclers differed from one another and controls on performance of a complex (Cincinnati) maze and on the development of the air-righting reflex. Offspring prenatally exposed to MPH showed an early delay in air-righting. ETH and HYD offspring were not consistently different from controls in behavior. The data suggest the following ordinal relationship among the drugs for behavioral teratogenesis: PHT much greater than MPH greater than ETH congruent to HYD congruent to CON. The effects of PHT are consistent with previous findings. Data on the other drugs suggest that other hydantoins do not possess the behavioral teratogenic efficacy of PHT and that PHT may be unique in its effects on CNS development.

Animals↗

PubMed2005

Electromyographic activity of dorsal neck muscles in squirrel monkeys during rotations in an upright or upside down posture.

Electromyographic (EMG) activity was recorded from occipitoscapularis, semispinalis, and splenius neck muscles in five alert squirrel monkeys during 0.25-Hz rotations about horizontal axes oriented at 22.5 degrees intervals, including pitch, roll, and intermediate axes. The animals were oriented in either upright or upside down posture. In the upright posture, all monkeys exhibited compensatory EMG activity with maximal activation during rotations about axes between pitch in the pitch forward direction and contralaterally directed roll. Response timing varied across animals with EMG peaks ranging from near pitch forward head velocity to near pitch forward head position. When the head was upside down, response dynamics and directionality were altered to varying degrees in different monkeys. The greatest change in response to head inversion was seen in the monkey that had response phases closest to head position, the least in the animal with phases closest to head velocity. The monkey with EMG response peaks closest to position phase showed nearly 180 degrees inversion of responses when the head was upside down, suggesting that in this monkey a righting reflex mediated by utricular signals was activated in the upside down posture. The monkey with EMG response peaks closest to velocity phase may have lacked a righting response and exhibited only a canal-mediated compensatory vestibulocervical reflex in both upright and upside down postures. The results suggest that reflex contraction of neck muscles in response to passive head rotation includes an interplay of compensatory and righting responses that varies from animal to animal.

Animals↗

PubMed1994

The grasp reflex from the right and left hand in human neonates indicates that the development of both cerebral hemispheres in males, but only the right hemisphere in females, is favoured by testosterone.

The grasp reflex was studied in relation to serum free testosterone levels in human neonates. In the total and -FS (no familial sinistrality) males, the grasp reflex (especially that from the right hand) significantly increased as testosterone increased. In the total and -FS females, there was a significant positive linear correlation between testosterone and the grasp-reflex strength from the left hand, but not from the right hand. In +FS males, there was a significant negative correlation between the grasp-reflex strength from the left hand and testosterone, but not from the right hand; there were no significant correlations in the +FS females. The right minus left (R - L) grasp-reflex strength linearly increased with testosterone in females with normal testosterone levels, but linearly decreased in females with high testosterone levels. The log R - L grasp reflex increased with testosterone in males. It was concluded that testosterone may be beneficial for the development of the left brain in -FS males and the left brain in -FS females, but may have detrimental effects on the right brain in +FS males. The growth-promoting asymmetric effects of testosterone on the brain may depend upon genetic organization of the brain.

Brain↗