Intranuclear crystalloids in arcuate nucleus neurons after clomiphene citrate administration

Summary The action of high doses of clomiphene citrate on the nuclei of hypothalamic arcuate neurons of male cats has been studied. Clomiphene produces an accumulation of typical crystalloid material in the nuclei. After administration of a protein-synthesis inhibitor, no such material was observed in clomiphene-treated animals.These ultrastructural features could possibly be due to a more intense protein synthesis in the hypothalamic arcuate neurons.     

Neuron numbers in hypothalamic nuclei of young, middle-aged and aged male rats

Morphologic analysis of nine hypothalamic areas revealed significant decreases in the number of neurons per unit area in the ventral medial and arcuate nuclei. These data suggest that altered neuron numbers in the VMW and perhaps the ARC may participate in the well documented reductions in endocrine and neuroendocrine function observed in aging rats.     

Neuron numbers in hypothalamic nuclei in young,middle-aged and aged male rats

Summary Morphologic analysis of nine hypothalamic areas revealed significant decreases in the number of neurons per unit area in the ventral medial and arcuate nuclei. These data suggest that altered neuron numbers in the VMW and perhaps the ARC may participate in the well documented reductions in endocrine and neuroendocrine function observed in aging rats.     

Ablation of LMO4 in glutamatergic neurons impairs leptin control of fat metabolism

The LIM domain only 4 (LMO4) protein is expressed in the hypothalamus, but its function there is not known. Using mice with LMO4 ablated in postnatal glutamatergic neurons, including most neurons of the paraventricular (PVN) and ventromedial (VMH) hypothalamic nuclei where LMO4 is expressed, we asked whether LMO4 is required for metabolic homeostasis. LMO4 mutant mice exhibited early onset adiposity. These mice had reduced energy expenditure and impaired thermogenesis together with reduced sympathetic outflow to adipose tissues. The peptide hormone leptin, produced from adipocytes, activates Jak/Stat3 signaling at the hypothalamus to control food intake, energy expenditure, and fat metabolism. Intracerebroventricular infusion of leptin suppressed feeding similarly in LMO4 mutant and control mice. However, leptin-induced fat loss was impaired and activation of Stat3 in the VMH was blunted in these mice. Thus, our study identifies LMO4 as a novel modulator of leptin function in selective hypothalamic nuclei to regulate fat metabolism.     

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

Microinjection of insulin (0.04-0.12 IU/microliter) into the anterior hypothalamus or the lateral hypothalamus, but not the ventromedial 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 insulin 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.     

Glutamate decarboxylase activity in preoptic and hypothalamic nuclei of the rat

Summary Freeze-dried samples were used for the determination of glutamate decarboxylase activity in discrete preoptic and hypothalamic nuclei. The activity showed marked regional variation in distribution.     

Long-term depressor effects of noradrenaline and dopamine neurons transplanted into the third ventricle of the brain of salt-loaded hypertensive rats

Neural tissues including A 6 group noradrenaline neurons in the locus ceruleus or A 10 group dopamine neurons in the substantia nigra were transplanted into the third ventricle at the preoptic-anterior hypothalamic level of rats made hypertensive by salt loading. Either transplant exerted a long-lasting depressor effect.     

Application to the study of connections in the CNS of the retrograde axonal transport of an iron-dextran complex]

The retrograde axonal transport of an iron-dextran complex was observed in neurons of the substantia nigra and of the intralaminar nuclei of the thalamus, after previous injection into the striatum. The histochemical demonstration of iron is simple and rapid, and can be combined with that of horseradish peroxidase, under precise conditions in the sequence of reactions. The iron-dextran complex revealed to be a valuable material for neuronal connectivity studies in the central nervous system.     

Fluoreszenzmikroskopische Untersuchungen am Hypothalamus männlicher Ratten nach Behandlung mit einer antimaskulin wirkenden Substanz

Summary In new-born male rats daily injections of a strong antiandrogenic substance led to an increase of the catecholamine content in the parvicellular perikarya as well as in nerve fibres leading to the paraventricular and supraoptic nuclei. The same effect was observed in male rats castrated immediately after birth. A possible relationship between gonadotropic releasing factors and the catecholamin content of the hypothalamic nuclei is discussed.     

Long-term depressor effects of noradrenaline and dopamine neurons transplanted into the third ventricle of the brain of salt-loaded hypertensive rats

Summary Neural tissues including A 6 group noradrenaline neurons in the locus ceruleus or A 10 group dopamine neurons in the substantia nigra were transplanted into the third ventricle at the preoptic-anterior hypothalamic level of rats made hypertensive by salt loading. Either transplant exerted a long-lasting depressor effect.     

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).     

Effects of thyroidectomy on monoamine oxidase activities toward tyramine and serotonin in the circumventricular nuclei of the rat.

Following thyroidectomy, monoamine oxidase (MAO) activities toward tyramine decreased significantly by 20% in the nucleus periventricularis and the nucleus arcuatus among the 3 hypothalamic nuclei of the rat, while MAO activity toward serotonin decreased significantly by 10% only in the nucleus periventricularis. It is suggested that thyroidectomy induced selective changes on the multiple forms of MAO in the discrete circumventricular nuclei.     

Effects of thyroidectomy on monoamine oxidase activities toward tyramine and serotonin in the circumventricular nuclei of the rat

Summary Following thyroidectomy, monoamine oxidase (MAO) activities toward tyramine decreased significantly by 20% in the nucleus periventricularis and the nucleus arcuatus among the 3 hypothalamic nuclei of the rat, while MAO activity toward serotonin decreased significantly by 10% only in the nucleus periventricularis. It is suggested that thyroidectomy induced selective changes on the multiple forms of MAO in the discrete circumventricular nuclei.     

Immunocytochemical localization of neurons containing ACTH 17-39 in the rat brain]

Immunoreactive neurons and fibers were localized in the Rat brain by immunocytochemistry using an anti-ACTH 17-39 antiserum. Neither adrenalectomy nor water deprivation affected intensity of distribution of reaction of labelled neurons whereas colchicine increased labelling of hypothalamic perikarya. These results support the neuronal origin of cerebral ACTH.     

Electrophysiology of mammalian hypothalamic and interpeduncular neurons in vitro.

Electrical activities of the hypothalamic and interpeduncular neurons were studied in vitro in brain slices prepared from the guinea-pig brain stem. Neurons preserved resting membrane potentials comparable to those of neurons in vivo, responded to stimulation of the afferent fibres, and retained stable spontaneous firings for more than several hours.     

Electrophysiology of mammalian hypothalamic and interpeduncular neurons in vitro

Summary Electrical activities of the hypothalamic and interpeduncular neurons were studied in vitro in brain slices prepared from the guinea-pig brain stem. Neurons preserved resting membrane potentials comparable to those of neurons in vivo, responded to stimulation of the afferent fibres, and retained stable spontaneous firings for more than several hours.     

Autoradiographic analysis of the primary visual projections of a diurnal predator (Buteo buteo L.)]

Radioautographic analysis of the optic system of a Common Buzzard (Buteo buteo L.) show hypothalamic (Meier's areas 1, 2 and 3), thalamic (nuclei lateralis anterior, geniculatus lateralis ventralis, dorsolateralis anterior), pretactal (nuclei geniculatus lateralis pretectalis--or Kuhlenbeck's geniculatus lateralis dorsalis--superficialis synencephali, griseus tectalis and area pretectalis), tegmental (nucleus ectomammillaris) and tectal visual projections. A general survey of Common Buzzard optic structures suggest a certain preponderancy of tectofugal system on thalamofugal system. Centrifugal visual system is reduced.     

Lesions in suprachiasmatic nuclei simulate effects of pinealectomy on prolactin release in ovariectomized and sulpiride-treated female rats

Previous studies indicate that the pineal gland alters prolactin secretion, and it was suggested that at least part of the effect of the pineal hormone melatonin on prolactin release may be mediated by the hypothalamic structures. In this study, pinealectomy and lesions of the suprachiasmatic nuclei were found to alter serum levels of prolactin in the same direction, an effect that was counteracted by daily afternoon melatonin administration. Melatonin, but not other pineal indoles, also prevented sulpiride-induced prolactin secretion in pinealectomized or suprachiasmatic nuclei-lesioned and ovariectomized rats, which suggested that the pineal gland can modulate prolactin secretion by acting through a dopamine mechanism independent of hypothalamic suprachiasmatic structures.     

Fluorescence histochemical demonstration of the uptake of dopamine-derived dihydroisoquinoline in the hypothalamic neurons

Summary The uptake and the accumulation of dopamine-derived fluorescent dihydroisoquinoline were demonstrated with direct fluorescence histochemistry in the hypothalamic dopaminergic neurons, in the nerves of the neurointermediate lobe, and in some endocrine cells of the hypophysis of the rat.     

Enzymhistochemische Untersuchungen an durstaktivierten neurosekretorischen Zellen der Ratte

Summary In hypothalamic neurosecretory nuclei of rats subject to water withdrawl for 1–14 days, a marked increase in the activities of histochemically detected acid phosphatase, thiamine pyrophosphatase and glucose-6-phosphate dehydrogenase is observed. LDH and SDH activities do not change. Two different cell types can be distinguished by means of the acid phosphatase and TPPase reactions.