Morton E. Weichsel

Epidermal Growth Factor in Synaptosomal Fractions of Mouse Cerebral Cortex

Abstract: Using a specific and sensitive epidermal growth factor radioimmunoassay (EGF‐RIA) we measured EGF concentrations in whole brain, cerebral cortex, and cerebral cortical synaptosomal (pinched‐off presynaptic nerve terminals) fractions of 26‐day‐old mouse brain. The relative EGF concentration in synaptosomal fractions was significantly greater than the growth factor concentrations in whole brain or cerebral cortex. Intracerebral injection, in an amount of EGF, several‐fold greater than whole brain EGF content, did not appreciably increase synaptosomal EGF concentration, suggesting that no artifact was involved. The high synaptosomal EGF content suggests a neurotransmitter or a neuromodulator role for EGF in the CNS.

Ontogenesis of Nerve Growth Factor and Epidermal Growth Factor in Submaxillary Glands and Nerve Growth Factor in Brains of Immature Male Mice: Correlation with Ontogenesis of Serum Levels of Thyroid Hormones

Summary: Using specific and sensitive radioimmunoassays for nerve growth factor (NGF) and epidermal growth factor (EGF), we studied the developmental profile of NGF and EGF concentrations in male mouse submaxillary gland (SMG) from 2–60 days of age. We measured NGF concentrations in mouse cerebellum, cerebral cortex, and brain stem from ages 2–32 days. In addition, we assessed mouse serum thyroxine (T4) and triiodothyronine (T3) levels in seperate groups of animals ranging from 5–50 days of age. Mean SMG EGF content and concentration exceeded that of NGF between 2 and 18 days of age. At all subsequent ages, however, mean NGF and EGF content and concentration were similar. SMG NGF and EGF content were low at 2 days of age, decreased slightly through 8 days of age, and increased exponentially after 11 days of age with three phases of increase being apparent for both proteins. In the first phase, mean SMG NGF and EGF contents increased 2.4− and 2.3-fold respectively between 11 and 18 days of age. A second phase of increase was noted between 18 and 32 days when NGF and EGF increased 9845− and 7805-fold respectively. In phase three (32–60 days of age) more modest increases of 6.5-fold in mean NGF and EGF content were noted.Cerebellar NGF concentrations increased from 681 to 2241 pg/mg protein between ages 2 and 15 days and subsequently fell to a plateau level of 1304 pg/mg protein by age 18 days. Cerebral cortical NGF concentrations increased steadily from 251 to 1383 pg/mg protein between ages 2 and 32 days, whereas brain stem NGF concentrations maintained a plateau averaging 1100 pg/mg protein.Serum T4 concentrations in the mouse increased dramatically from 2.5 μg/dl at 5 days to a maximum of 8.1 μ/dl at 15 days, thereafter decreasing to a nadir 4.4 μ/dl by 40 days. Serum T3 concentrations followed a similar pattern, rising from 25 ng/dl on postnatal day 5 to 93 ng/dl on day 15, with a subsequent decline to 63 ng/dl by day 30. These results indicate a correlation between the increase in serum thyroid hormone levels in the mouse and the increases in SMG NGF and EGF levels and brain NGF levels between 5 and 32 days.Speculation: We and others have demonstrated that thyroid hormones increase brain NGF concentrations and stimulate submaxillary gland NGF and EGF synthesis. The present results are compatible with the hypothesis that the early increase in circulating thyroid hormone concentrations in the mouse play an important role in the increase in cerebral and cerebellar NGF levels during the first 3 wk and the increase in SMG NGF and EGF concentrations between 11 and 32 days of age. The known increase in mouse serum testosterone to adult male levels between 4–12 wk of age may be a factor in the late increase in NGF and EGF elevations after 32 days of age.

Synthesis and secretion of a nerve growth-stimulating factor by neonatal mouse astrocyte cells in vitro.

ABSTRACT. Neonatal mouse astroglial cells cultured in a serum-free medium synthesize and secrete a trophic growth factor which resembles nerve growth factor (NGF). The NGF-like factor reacts with antiserum to β subunit of NGF(β-NGF) and, after labeling with [35S] cystine, migrates similarly to purified mouse β-NGF in SDS polyacrylamide gel electrophoresis and Sephadex G-100 gel filtration systems. The astrocyte cell NGF-like factor displays β-NGF-like neurite growth-promoting activity for the clonal rat pheochromocytoma (PC-12) cell line and this bioactivity is blocked by β-NGF antiserum. These results indicate that NGF-like factor synthesized and secreted by astroglial cells, is similar, if not identical, to β- NGF from the mouse submandibular gland and further support a potential role for NGF in the central nervous system.

Effect of thyroxine on nerve growth factor concentration in neonatal mouse brain

Abstract The effect of T4 administration on central nervous system nerve growth factor (NGF) concentration was studied in 12 day old mice. Neonatal mice received T4 (0.4 or 1.6 ug/g body weight) daily for 11 days after birth. On the 12th day, NGF concentration was measured in cerebral cortex, cerebellum and brain stem using a specific radioimmunoassay for the biologically active beta subunit of NGF; this assay is sensitive to 10–15 pg NGF. T4 administration caused a dose related decrease in mean body weight to 86% and 77% of control body weight for the low and high T4 doses respectively. Mean cerebral cortex and cerebellum weights (corrected for body weight) were significantly increased in the T4 treated mice. Brain stem weight, however, was significantly decreased. T4 (0.4 ug/g body weight) caused a significant increase in mean NGF concentration (pg/mg protein) in cerebral cortex (26%; p Brain maturation in neonatal rodents occurs largely during the first 2–4 weeks of postnatal life; and thyroid hormones are essential for the orderly and sequential progress of this maturation. Thyroid hormone excess accelerates histological and biochemical maturation of the immature central nervous system (1–3) (CNS) whereas thyroid hormone deficiency results in significant delays in the attainment of biochemical and histological landmarks of maturation (1, 2, 4). The mechanism of this thyroid hormone effect is unknown. Specific nuclear binding sites for thyroid hormones are present in high concentrations in the immature CNS (5, 6). However thyroid hormone effects observed in other thyroid hormone responsive tissues, i.e., liver and kidney, following thyroid hormone binding to specific nuclear receptors are not observed in the immature brain (7). We have previously shown that thyroxine (T4) administration to mature male mice significantly increases nerve growth factor (NGF) content and concentration in cerebral cortex, cerebellum and brain stem (8). The present studies were conducted to determine whether thyroxine influences CNS NGF during the period of neonatal brain maturation to support the hypothesis that the thyroid hormone effects on CNS maturation may be mediated by NGF.

Human nerve growth factor: Lack of immunocrossreactivity with mouse nerve growth factor

Abstract Human β-nerve growth factor (hNGF) was purified from term human placenta. The biological potency of hNGF in the chick dorsal root ganglion assay did not differ significantly from that of mouse NGF (mNGF). Molecular weight determinations of mNGF and hMGF were also similar. No immunological crossreactivity was noted between hNGF, at a concentration of 100 μg/ml, and mNGF in a radioimmunoassay for mNGF using 6 different antisera to mNGF. hNGF shares several properties with mNGF but is immunological distinct. The results of studies in man using antisera to mNGF should be interpreted with caution.

Acute cerebellar hemorrhage in childhood: etiology, diagnosis, and treatment.

Four cases of acute cerebellar hemorrhage in childhood are reported. Two were related to the rupture of arteriovenous malformations, one was a hemorrhage within a cerebellar tumor, and one (in a neonate) was of an undetermined etiology. Three of the cases were treated surgically, whereas the neonatal hemorrhage was managed medically. The latter case seems to be the only reported case of acute cerebellar hemorrhage in childhood that resolved spontaneously. Computed tomographpy proved to be invaluable in the diagnosis, management, and follow-up of the patients. Although surgical treatment is indicated when identifiable lesions cause the hemorrhage, nonsurgical approaches may be satisfactory when lesions are not discernible. Our cases, in addition to those reported previously, suggest a better prognosis for children than for adults with acute cerebellar hemorrhage, regardless of the etiology.

Neonatal hypothyroidism — A biochemical disorder of α-tubulin metabolism☆

Abstract In mouse brain significant changes in tubulin-tyrosine ligase (TTL) activity were observed during the first week of neonatal life. Brain TTL-activity was found to be higher on postnatal day 5 than on fetal day 15, at birth or on postnatal day 7. In neonatal hypothyroidism both TTL activity and endogenous tyrosinable-tubulin levels were greatly reduced on day 5 relative to euthyroid animals. Gel scanning studies did not show any qualitative differences in the brain supernatant protein patterns of euthyroid and hypothyroid animals. Under conditions of the present study α-tubulin was only substrate for tyrosylation.

Effect of Hypothyroidism on Aspartate Transcarbamylase, Uridine Kinase, and DNA Biosynthesis during Cerebellar Development in the Rat

Experimental hypothyroidism in the neonatal rat is known to retard cerebellar DNA biosynthesis with a return to normal of the ultimate cell number. Because of the known shift to a later age in the dev

Correlation of DNA Accumulation Rate with Thymidylate Synthetase Activity in Developing Rat Cerebellum: Effect of Hypothyroidism

Experimental hypothyroidism in the neonatal rat is known to result in a delay in cerebellar DNA biosynthesis. Because of the known high correlation between rate of DNA biosynthesis and thymidylate syn

Thyroxine Effect upon Activity of Uridine Kinase in Developing Rat Cerebellum

Experimental hyperthyroidism in the neonatal rat is known to accelerate cerebellar DNA biosynthesis resulting ultimately in a deficit in cell number at maturity. Because of the know shift to an earlier age in the developmental curve for cerebellar thymidine kinase activity in rats treated with thyroxine, we studied the activity of uridine kinase and DNA biosynthesis during rat cerebellar development under hyperthyroid conditions. Body weight and cerebellar wet weight in treated animals were noted to be significantly decreased below control values on days 4 and 12, respectively. Cerebellar DNA was significantly elevated above control values on days 4 and 6 (132 and 129% of control, respectively). Subsequently, DNA content fell significantly below control values through day 18. Uridine kinase activity was found to be increased significantly above control values at ages 2, 4, and 6 days (maximum 119% of control at age 4 days) following which activity fell significantly below control values by 15 days of age. Uridine kinase activity from both treated and control animals fell only moderately after the time of peak activity between 9 and 15 days of age, although the peak of the developmental curve for the enzyme appeared earlier in the treated animals. The data show a less pronounced early stimulation of cerebellar uridine kinase by thyroxine compared with previously reported thyroxine enhancement of thymidine kinase activity, although both enzymes are affected by thyroxine throughout cerebellar ontogenesis. The study thus provides evidence that uridine kinase is sensitive to hormonal stimulation during early stages of active cerebellar cell division, and that the enzyme may relate most closely in brain to the synthesis of RNA as well as the sustaining of cell function after the most active phase of cellular proliferation. In addition, the study emphasizes the use of enzyme-hormone relationships during development to provide information concerning critical interrelationships between metabolic pathways contributing to nucleic acid biosynthesis.