Hypothalamic histamine modulates adaptive behavior of rats at high environmental temperature

Summary Histamine content in the rat hypothalamus was lower at 4°C and higher at 31°C compared to that at 21°C. Pretreatment with -fluoromethylhistidine, a suicide inhibitor of histidine decarboxylase, attenuated both the increased level of hypothalamic histamine and rat adaptive behavior at 31°C. Increase of histamine content in the hypothalamus appears to be an important factor contributing to rat adaptive behavior to high environmental temperature.     

Role of calcium in the histamine release induced by D-galactosamine from rat mast cells

Rat peritoneal mast cells were isolated and purified by differential centrifugation in Ficoll. Cells pooled from three to four rats were suspended at approximately 10(6) cells/ml in a buffered salt solution and incubated for 1 h at 37 degrees C in 300 microliter volumes in the absence or presence (9 X 10(-4) M) of calcium chloride. Addition of D-galactosamine hydrochloride (DGM; 2.8 X 10(-4)M) caused (in addition to basal release) a mean +/- SEM percent histamine release of 15.7 +/- 5.2 in the presence of Ca++ and 19 +/- 4.9 in the absence of Ca++ (p greater than 0.05). It is suggested that D-galactosamine does not require extracellular Ca++ for the release of histamine from the rat mast cell.     

Modification du métabolisme de la dopamine cérébrale provoquées par l'injection intrapéritonéale d'une forte dose d'histamine chez le rat

Summary A dose of 400 mg/kg of histamine chlorhydrate, injected i.p., induces in the rat an increase of synthesis of dopamine in the neostriatum and in the cortex with an inhibition of its degradation in the hypothalamus. However, the kinetics of these effects are not correlated with behavioral changes.     

Post mortem changes in adenylate cyclase activity in rat brain striatum

Adenylate cyclase activity in rat striatum decreased post mortem. Half-lives were about 2.7 h at 22 degrees C, 72 h at 4 degrees C. Differences in stability after death of adenylate cyclase in human brain and rat striatum, and possible heterogenity of the enzyme, are briefly discussed.     

Isonicotinic acid hydrazide: early effects on peripheral nerve conduction velocity

This report describes the effects of short treatments with isonicotinic acid hydrazide (isoniazid), 300 mg/kg/day, on conduction velocity in the rat tail dorsal nerve trunk. After 6 days of continuous treatment, conduction velocity falls significantly for measurements made at 35 degrees C. After 10 days it falls significantly at both 25 degrees C and 35 degrees C. This appears to be the first electrophysiological corroboration of the early neuropathological changes recently observed in isoniazid treated rats and seems to provide evidence that the temperature at which the experiments are made is important in determining conduction velocity changes.     

Effects of hypothalamic injections of 5,6-dihydroxytryptamine on thermoregulation in rats.

5,6-Dihydroxytryptamine, a serotonin depletor, infused directly into the anterior hypothalamus of rat's brain, produced an increase in both heat production and heat loss (as indicated by changes in peripheral circulation) at temperatures of 8, 15 and 22 degrees C. The rectal temperature of these treated rats remained constant.     

Increased erythrocyte permeability to Li and Na in the spontaneously hypertensive rat.

Red blood cells incubated in a physiological medium in which Li replaces Na (LiPSS) gain Li in exchange for Na and K. The rate of Li uptake is modestly but significantly increased in the spontaneously hypertensive rat (SHR) at 37 degrees C and at 22 degrees C. The slow rate of Na gain and K loss during cooling at 2 degrees C was about doubled in unmodified whole blood samples from the SHR.     

Improved separation at low temperature of glycoproteins by Con A-Sepharose affinity chromatography in the presence of sodium dodecyl sulfate (SDS)

The Con A-Sepharose affinity chromatography of glycoproteins was even more effective at 4 degrees C than that at room temperature (26-28 degrees C) in the presence of sodium dodecyl sulfate (SDS). Application of this methodology to the separation of several glycoproteins from SDS-solubilized membrane proteins in rat cerebellum, including a glycoprotein characteristic of the Purkinje cells, was successful.     

Adenosine-3,5-phosphate levels in brain structures of rats submitted to four different behavioral procedures

Shuttle avoidance training decreased the cAMP content of rat brain (excluding hippocampus and caudate nucleus), amygdala and hypothalamus. Stimulation by tones alone had a similar effect, but only in the brain fraction. Pseudoconditioning or footshocks alone had no effect.     

Temperature dependence of neurotransmitter release in the antarctic fish Pagothenia borchgrevinki

The quantal contents of endplate potentials from extraocular muscles of an antarctic fish Pagothenia borchgrevinki were measured over a range of temperatures. Quantal release was maximal at about 5 degrees C but showed little dependence on temperature between -2 degrees C and 10 degrees C. Above 10 degrees C quantal content declined until release ceased about 18 degrees C. In view of the fact that the ambient temperature at which these fish live is constant at -1.9 degrees C, the results suggest that Pagothenia borchgrevinki is only partially adapted to its environment despite 25 million years acclimatization.     

Effect of stress on choline acetyltransferase activity of the brain and the adrenal of the rat.

Choline acetyltransferase (ChAT) activity was determined in cerebral cortex, hypothalamus, hippocampus, cerebellum, medulla oblongata, midbrain and adrenal gland of rats exposed to acute or chronic stress. The exposure of animals to acute immobilization and cold stress (4 degrees C) for one hour resulted in a significant decline of ChAT activity in all brain regions examined except for the medulla oblongata. Moreover, the exposure to acute stress resulted in significant increase of the same enzyme in the adrenal gland. However, chronic exposure of animals to cold stress (4 degrees C) for 7 days resulted in no significant changes of ChAT activity in all tissues examined except for a decline in the midbrain and an increase in the medulla oblongata. The administration of corticosterone (2.0 mg/kg) 1 h prior to sacrificing caused an effect similar to that of acute stress on ChAT activity in all brain regions except for the hypothalamus and the cerebellum. It was concluded from this experiment that stress-induced changes in the ChAT activity of specific brain regions might be mediated by the adrenal steroids.     

Role of calcium in the histamine release induced by D-galactosamine from rat mast cells

Summary Rat peritoneal mast cells were isolated and purified by differential centrifugation in Ficoll. Cells pooled from three to four rats were suspended at approximately 10⁶ cells/ml in a buffered salt solution and incubated for 1 h at 37°C in 300 l volumes in the absence or presence (9×10^–4 M) of calcium chloride. Addition of D-galactosamine hydrochloride (DGM; 2.8×10^–4 M) caused (in addition to basal release) a mean ±SEM percent histamine release of 15.7±5.2 in the presence of Ca⁺⁺ and 19±4.9 in the absence of Ca⁺⁺ (p>0.05). It is suggested that D-galactosamine does not require extracellular Ca⁺⁺ for the release of histamine from the rat mast cell.A preliminary analysis of these results was presented at the International Symposium on calcium entry blockers and tissue protection, Rome, 15–16 March 1984.     

Control of pituitary secretion of melanotropin in an anuran amphibian by thyrotropin releasing factor (TRH). Study in vitro]

Intermediate lobes from Rana esculenta pituitary glands were continuously superfused for 7 hrs at 28 degrees C with amphibian culture medium. alpha-MSH release was measured by use of a sensitive double antibody radio-immunoassay system. alpha-MSH secretion was inhibited by low temperatures. A large increase in alpha-MSH release was observed when Thyrotropin Releasing Hormone (TRH) at doses ranging from 10(-9) to 10(-7) molar was added to the superfusion medium. Since large amounts of TRH are to be found in the hypothalamus of amphibians but have no effect over pituitary TSH secretion, the action of TRH over alpha-MSH release may have a physiological significance.     

Insulin acts on the hypothalamic glucose-facilitated neurons to induce hyperglycemia and hyperinsulinemia in the rat

Microinjection of insulin (0.04–0.12 IU/l) into the anterior hypothalamus or the lateral hypothalamus, but not the vertromedial hypothalamus of the rat brain, caused a dose-dependent rise in blood glucose and in serum insulin. The majority (71.5%) of the glucose-facilitated neurons recorded in the lateral hypothalamic area were excited by intracerebral injection of insulin. The data indicate that insulni acts on the hypothalamic glucose-facilitated neurons to induce hyperglycemia and hyperinsulinemia. It is unknown whether insulin normally reaches the hypothalamic area, or how it might do so.This work was supported by grants from the National Science Council (Taipei, Taiwan, Republic of China).     

Adenosine-3,5-phosphate levels in brain structures of rats submitted to four different behavioral procedures

Summary Shuttle avoidance training decreased the cAMP content of rat brain (excluding hippocampus and caudate nucleus), amygdala and hypothalamus. Stimulation by tones alone had a similar effect, but only in the brain fraction. Pseudoconditioning or footshocks alone had no effect.With support from FAPERGS, CNPq, and PROPESP-UFRGS, Brasil. We are grateful to Miss Sonia Eisinger for her valuable technical assistance.     

Colchicine inhibits stimulated release of gastric histamine but not activation of histidine decarboxylase.

In the rat, gastric mucosal histamine is mobilized and histidine decarboxylase activated by treatment with insulin or pentagastrin. Colchicine pretreatment prevented the histamine release without preventing the enzyme activation. The results suggest a) that histamine release and histidine decarboxylase activation are independent events, and b) that microtubules are involved in the release of histamine.     

Activation-induced cellular accumulation of histamine in immature but not mature murine mast cells

Mast cell activation involves the rapid release of inflammatory mediators, including histamine, from intracellular granules. The cells are capable of regranulation and multiple rounds of activation. The goal of this study was to determine if there are changes in the content of pre-formed mast cell mediators after a round of activation. After 24 h, the histamine content of bone marrow-derived mast cells (BMMC), but not that of peritoneal mast cells, exceeded the amount in resting cells. Accumulation of histamine in BMMC peaked at 72 h of activation, and returned toward preactivation levels by 96 h. The increase in histamine content was accompanied by an increase in the gene expression of histidine decarboxylase. No increases in beta hexosaminidase or murine mast cell protease-6 were observed. These findings indicate that BMMC respond to activation by increasing total cell-associated histamine content. This increase may be important to the response of these cells upon subsequent exposure to antigens.     

Colchicine inhibits stimulated release of gastric histamine but not activation of histidine decarboxylase

Summary In the rat, gastric mucosal histamine is mobilized and histidine decarboxylase activated by treatment with insulin or pentagastrin. Colchicine pretreatment prevented the histamine release without preventing the enzyme activation. The results suggest a) that histamine release and histidine decarboxylase activation are independent events, and b) that microtubules are involved in the release of histamine.     

Stimulation of histamine synthesis in rat mast cells by compound 48/80 in vitro

The histamine content of rat peritoneal fluid cells is doubled within 20 min by 0.5 microgram/ml of compound 48/80. Histamine catabolism inhibitors do not reproduce this effect; cells pre-incubated with alpha-fluoromethylhistidine are unresponsive to compound 48/80 which therefore activates pre-formed histidine decarboxylase rather than 'inducing' it. Non-mast cells showed no change after treatment with compound 48/80.     

Cytoplasmic contaminants in Triton X-100 washed rat liver nuclei - a possible way of further purification.

The presence of cytoplasmic contaminants is demonstrated in preparations of rat liver nuclei, even after washing with Triton X-100. They can be removed by incubation at 37 degrees C in a medium of low-salt concentration.