Brain Of Adult Male Rats Research Articles

The effect of bilateral lesions of the ventral noradrenergic bundle on endocrine-induced changes of tyrosine hydroxylase in the rat median eminence.

With the microdissection method of Palkovits, individual hypothalamic nuclei were removed from the brains of adult male rats, and the tyrosine hydroxylase (TH) activity of each nucleus was determined 7 days after gonadectomy or thyroidectomy. Following gonadectomy, TH activity increased significantly in the median eminence with no change in the periventricular (NPV), arcuate (NARC), and dorsomedial nuclei (NDM), or medial forebrain bundle (MF). Following thyroidectomy, TH activity increased significantly in all 5 hypothalamic nuclei examined. Placement of bilateral lesions in the ventral norepinephrine bundles resulted in a greater than an 85% fall in the dopamine-beta-hydroxylase activity of the median eminence, arcuate nucleus, and ventromedial nucleus, but had no effect on tyrosine hydroxylase activity measured in those same areas. Furthermore, placement of such lesions had no effect on the endocrine-induced increases of TH activity found in the median eminence following gonadectomy and thyroidectomy, but did prevent the increase of TH activity found in the NPV, NDM, and MFB following thyroidectomy. Three conclusions appear to be justified: (a) noradrenergic axons which innervate the median eminence, arcuate, and ventromedial nuclei course in the ventral norepinephrine bundles; (b) the TH content of noradrenergic neurons in the median eminence, arcuate nucleus, and ventromedial nuclei is quite small; and (c) the majority, if not all, of the endocrine-responsive catecholaminergic neurons in the median eminence are dopaminergic.

Estradiol-17β: a metabolite of testosterone recovered in cell nuclei from limbic areas of adult male rat brains

Estradiol-17β: a metabolite of testosterone recovered in cell nuclei from limbic areas of adult male rat brains

The effect of endocrinological manipulations on tyrosine hydroxylase and dopamine-beta-hydroxylase activities in individual hypothalamic nuclei of the adult male rat.

Using a recently developed microdissection method, individual hypothalamic nuclei were removed from the brains of adult male rats, and the tyrosine hydroxylase (TH) and dopamine-β- hydroxylase (DBH) activities in each nucleus were determined 9 days after adrenalectomy, thyroidectomy or gonadectomy. Following gonadectomy there was a significant rise in the TH activity in only the median eminence (ME). This increased TH activity was partially reversed by treatment of gonadectomized animals with testosterone. Thyroidectomy induced a significant increase in the TH activity in the ME, the dorsomedial (NDM), the periventricular (NPE) and the arcuate (NARC) nuclei. Twelve hr after administration of thyroxine, the TH activity in the ME of thyroidectomized rats was significantly reduced to levels below those of controls, whereas the TH activities of the other nuclei were returned to control values. Adrenalectomy produced a significant fall in TH activity in the ME, whereas dexamethasone significantly increased the...

Neonatal sterilization of rodents with steroid hormones: 5. A note on the influence of neonatal treatment with estradiol benzoate or testosterone propionate on steroid metabolism in the brain and testes of adult male rats

The influence of neonatal treatment with androgens or estrogens in rats was evaluated by measuring in the testes and the brain of adult animals the conversion of 4-androstene-3, 17-dione, 3β-hydroxy-5-androstene-17-one, 3β-hydroxy-5-pregnen-20-one, and testosterone. In the testes, neonatal treatment with estradiol benzoate produced an enzymatic defficiency manifested by decreased utilization of C-21 precursor and 17-oxo reduction. Neonatal treatment with testosterone propionate produced an increase in 17β-hydroxyoxidase activity and decrease in the activity of 17-oxo reductase. In addition, the amounts of testoster-one and androstenedione in the brain of treated rats were significantly decreased suggesting an alteration in the permeability of the blood-brain barrier.

DNA, RNA, and protein synthesis in brain, liver, and kidneys of asymptomatic methylmercury treated rats

Total mercury levels increased with dose in the brain, liver, and kidneys of adult male rats treated with methylmercury hydroxide. The distribution of mercury among these organs was constant over a seven day period in animals treated with 10 mg/kg/day. The brain, liver, and kidneys of animals treated with a total dose of 70 mg/kg contained 10, 113, and 260 ppm of mercury, respectively. These animals displayed no neurological signs of alkylmercury poisoning. Organ-specific changes in total content and synthesis of DNA, RNA, and protein occurred as the tissue mercury burden increased. In general, macromolecular synthesis was enhanced in the brain and liver, while inhibitory effects were predominate in the kidneys. The synthesis of proteins was more sensitive to mercury than nucleic acids. Total ribosome content and their distribution among their functional cytoplasmic compartments varied with alterations in protein synthesis activity, suggesting disturbances at the level of gene translation. The capacity to synthesize DNA was conserved in the liver and kidneys at elevated tissue mercury levels. The evidence presented advances the hypothesis that disturbances in protein synthesis is a fundamental aspect of alkylmercury poisoning.

Effect of central early postnatal 6-hydroxydopamine administration on brain catecholamines and pituitary-adrenal function in adulthood.

Central administration of 6-hydroxydopamine (6OHDA) to newborn rats induced a dose-dependent and long-lasting decrease in noradrenaline (NA) and dopamine (DA) content in adult male and female rat brain. After postnatal administration of 100 <i>µ</i>g 6OHDA, a decrease of about 50% of NA and DA content of the whole brain was found in 9- to 10-week-old rats; 200 <i>µ</i>g 6OHDA induced a reduction of 80 % of NA and DA content. The latter treatment was followed by a severe growth retardation, a marked myosis, a decrease in general activity, and disappearance of clonic convulsions after decapitation. At the same time, however, in both groups of animals no change in basal pituitary-adrenal activity was found, as evaluated by measurement of corticosterone in plasma, <i>in vitro </i>adrenal corticoid production, and adrenal weight. Apparently even severe inhibition of the development of central DA and NA systems by 6OHDA administration to the newborn rat did not induce any change in basal pituitary-adrenal functioning.

P32 uptake in hypophysectomized rats.

In a previous paper we have described the effect of adrenalectomy on the uptake of radioactive phosphorus (P32) in the rat (Lingjærde et al., 1958). The purpose of this investigation is to study the effect of hypophysectomy on the uptake of P32 by the brain, endocrine glands and other organs of adult male rats. The results obtained are different from those reported by other workers, probably because of different standards used for calculating the relative specific activities. Adult male Wistar rats hypophysectomized by the parapharyngeal route were obtained commercially, and used 6–7 weeks after operation. They were kept on the usual diet in our laboratory, and no substitutional therapy was given. No traces of pituitary tissue were found in any of the animals at autopsy. Administered intraperitoneally with a Krogh-Keys graduated 1 ml. syringe, exactly 250 microcuries of P32 are given to the animals 2.5 hours

Influence of various steroids on the oxidative function of rat tissue preparations.

This study was undertaken to ascertain what influence steroid hormones may have on tissue respiration, and secondly, if any effect could be demonstrated, which specific enzymes were involved. Early in the course of our work Gordon and Elliot (1947) reported that testosterone and other steroids depressed the in vitro aerobic respiration of rat brain in the presence of glucose. More recently Eisenberg, Gordon, and Elliot (1949) have reported that testosterone suspensions inhibit the oxygen uptake of rat brain, liver, and striated muscle slices. Our studies confirm and extend these studies. In this communication data on the inhibitory action of various steroids on oxygen uptake of liver, kidney, and brain preparations are presented, while another paper (Hayano and Dorfman, 1950) deals specifically with the inhibition of the D-amino acid oxidase system by desoxycorticosterone. Slices.—Livers, kidneys, and brains of adult male albino rats (100–200 g.) were removed shortly after the animals had been decapitated...