Direct Corticosteroid Modulation of GABAergic Neurons in the Anterior Hypothalamic Area of GAD65-eGFP Mice

Corticosterone is known to modulate GABAergic synaptic transmission in the hypothalamic paraventricular nucleus. However, the underlying receptor mechanisms are largely unknown. In the anterior hypothalamic area (AHA), the sympathoinhibitory center that project GABAergic neurons onto the PVN, we examined the expression of glucocorticoid receptor (GR) and mineralocorticoid receptor (MR) of GABAergic neurons using intact GAD65-eGFP transgenic mice, and the effects of corticosterone on the burst firing using adrenalectomized transgenic mice. GR or MR immunoreactivity was detected from the subpopulations of GABAergic neurons in the AHA. The AHA GABAergic neurons expressed mRNA of GR (42%), MR (38%) or both (8%). In addition, in brain slices incubated with corticosterone together with RU486 (MR-dominant group), the proportion of neurons showing a burst firing pattern was significantly higher than those in the slices incubated with vehicle, corticosterone, or corticosterone with spironolactone (GR-dominant group; 64 vs. 11~14%, p<0.01 by chi2-test). Taken together, the results show that the corticosteroid receptors are expressed on the GABAergic neurons in the AHA, and can mediate the corticosteroid-induced plasticity in the firing pattern of these neurons. This study newly provides the experimental evidence for the direct glucocorticoid modulation of GABAergic neurons in the AHA in the vicinity of the PVN.

Neonatal handling and the expression of immunoreactivity to tyrosine hydroxylase in the hypothalamus of adult male rats

Neonatal handling has long-lasting effects on behavior and stress reactivity. The purpose of the present study was to investigate the effect of neonatal handling on the number of dopaminergic neurons in the hypothalamic nuclei of adult male rats as part of a series of studies that could explain the long-lasting effects of neonatal stimulation. Two groups of Wistar rats were studied: nonhandled (pups were left undisturbed, control) and handled (pups were handled for 1 min once a day during the first 10 days of life). At 75-80 days, the males were anesthetized and the brains were processed for immunohistochemistry. An anti-tyrosine hydroxylase antibody and the avidin-biotin-peroxidase method were used. Tyrosine hydroxylase-immunoreactive (TH-IR) neurons were counted bilaterally in the arcuate, paraventricular and periventricular nuclei of the hypothalamus in 30-æm sections at 120-æm intervals. Neonatal handling did not change the number of TH-IR neurons in the arcuate (1021 + or - 206, N = 6; 1020 + or - 150, N = 6; nonhandled and handled, respectively), paraventricular (584 + or - 85, N = 8; 682 + or - 62, N = 9) or periventricular (743 + or - 118, N = 7; 990 + or - 158, N = 7) nuclei of the hypothalamus. The absence of an effect on the number of dopaminergic cells in the hypothalamus indicates that the reduction in the amount of neurons induced by neonatal handling, as shown by other studies, is not a general phenomenon in the brain

Location of CNS Labeled Neurons Innervating the Rat Thymus Using the Pseudorabies Virus / 체질인류학회지

This experimental studies was to investigate the location of CNS labeled neurons following injection of pseudorabies virus (PRV), Bartha strain, into the rat thymus. After survival times of 96~120 hours following injection of PRV, the rats were perfused, and their spinal cord and brain were frozen sectioned(30micrometer). These sections were stained by PRV immunohistochemical staining method, and observed with light microscope The results were as follows: 1. The PRV labeled spinal cord segments projecting to the rat thymus were founded in cervical and thoracic segments. Densely labeled areas of each spinal cord segment were founded in lamina V, VII, X, intermediolateral nucleus and dorsal nucleus. 2. In the rhombencephalon, PRV labeled neurons projecting to the thymus were founded in the A1 noradrenalin cells/C1 adrenalin cells/caudoventrolateral reticular nucleus, rostroventro-lateral reticular nucleus, medullary reticular nucleus, area postrema, nucleus solitary tract, nucleus raphe obscurus, nucleus raphe pallidus, nucleus raphe magnus, gigantocellular reticular nucleus, lateral paragigantocellular nucleus and spinal trigeminal nucleus. 3. In the mesencephalon, PRV labeled neurons were founded in parabrachial nucleus, Kolliker-Fuse nucleus, central gray matter, substantia nigra, nucleus dorsal raphe, A8 dopamin cells of retrorubral field, Edinger-Westphal nucleus, locus coeruleus, subcoeruleus nucleus and A5 noradrenalin cells. 4. In the prosencephalon, PRV labeled neurons were founded in reuniens thalamic nucleus, paraventricular thalamic nucleus, precommissural nucleus, paraventricular hypothalamic nucleus, anterior hypothalamic nucleus, lateral hypothalamic nucleus, preoptic hypothalamic nucleus, retrochiasmatic area, arcuate nucleus, dorsomedial hypothalamic nucleus and ventromedial hypothalamic nucleus. These results suggest that PRV labeled neurons of the spinal cord projecting to the rat thymus might be the neurons related to the viscero-somatic sensory and sympathetic preganglionic neurons, and PRV labeled neurons of the brain may be the neurons response to the movement of smooth muscle in blood vessels. These PRV labeled neurons may be central autonomic center related to the integration and modulation of reflex control linked to the sensory system monitoring the internal environment. These observations provide evidence for previously unknown projections from spinal cord and brain to the thymus which may be play an important role in the regulation of thymic function.

Coexistence of Tyrosine Hydroxylase and Nicotinamide Adenine Dinucleotide Phosphate-Diaphorase in Hypothalamic Neurons of the Rat / 대한해부학회지

The presence and coexistence of nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-diaphorase) with tyrosine hydroxylase (TH) was investigated by combining NADPH-diaphorase histochemistry with TH immunohistochemistry in hypothalamic nuclei of the rat. TH-immunoreactive and NADPH-diaphorase positive neurons were found in the medial preoptic area and medial preoptic nucleus, anterior hypothalamic area, dorsomedial hypothalamic nucleus, paraventricular nucleus, supraoptic nucleus and posterior hypothalamic area, respectively. TH and NADPH-diaphorase did not coexist in the anterior hypothalamic area, dorsomedial hypothalamic nucleus, medial preoptic area and posterior hypothalamic area. A considerable portion (30~50%) of the NADPH-diaphorase positive neurons in the supraoptic nucleus colocalized TH. In the medial preoptic area and paraventricular nucleus, some (5~15%) of TH-immunoreactive neurons also contained NADPH-diaphorase activity. NADPH-diaphorase is known to be an indicator of the enzyme nitric oxide synthase; these results therefore suggest that nitric oxide may play an important role in the regulation of the activity of the hypothalamic dopaminergic system of the rat.

Asymmetrical effects of the unilateral implant of pilocarpine on the preoptic-anterior hypothalamic area on spontaneous ovulation of the adult rat

The effects on ovulation at the next strus after unilaterally implanting pilocarpine in the preoptic-anterior hypothalamic area (POA-AHA) of rats on each day of the estrous cycle were analyzed. Implantation on the left side of POA-AHA on the day of estrus blocked ovulation in all animals, whereas implantation on the right side did not (0/5 vs. 4/4, p<0.05). Implantation on diestrus 1 or 2 on either side of the POA-AHA blocked ovulation. Implatation on the righ side of the POA-AHA at the day of proestrus blocked ovulation (1/6 animals ovulated), while 10/12 with pilocarpine on the left side ovulated (p<0.05).The administration of 3.7 µg of GnRH at 13:00 h o the expected day of proestrus induced ovulation in 36/42 treated animals. In rat with a pilocarpine implant, the injection of estradiol benoznate on diestrus 2 restored ovulation only in those animals with the pilocarpine implant placed in the left side of the POA-AHA, performed on the day of estrus. The results support the previous estatements that in the adult rat POA-AHA, the cholinergic mechanism regulating preovulatory GnRH release, is lateralized. In addition, at the beginning of the estrous phase, the PAO-AHA-cholinergic system needs to remain undisturbed for normal ovulation to take place at the next estrus

Dopaminergic Neurons in the Diencephalon of Striped Field MouseApodemus agrarius coreae / 대한해부학회지

The distributions and morphological characteristics of neurons displaying immunoreactivity to the catecholamine synthetic enzymes, tyrosine hydroxylase[TH], dopamine-beta-hydroxylase[DBH], and phenyletha-nolamine-N-methyltransferase[PNMT] were examined in the adjacent sections of the diencephalon of the striped field mouse [Apodemus agrarius coreae].Only TH-, and no DBH- or PNMT-immunoreactive neurons were found in the diencephalon. In the preoptic area, TH-immunoreactive neurons were found in the anterior preoptic nucleus of Loo[APN], periventricular preoptic nucleus, medial preoptic nucleus, lateral preoptic nucleus and suprachiasmatic nucleus. In the hypothalamus, TH-immunoreactive neurons were found in theparaventricular hypothalamic nucleus, periventricular gray, retrochiasmatic area,anterior hypothalamic nucleus of anterior hypothalamic area and retrochiasmatic region of the hypothalamus. In the rostral tuberal region of the hypothalamus, TH-immunoreactive neurons were found in the paraventricular nucleus, periventricular gray and arcuate nucleus. In the midtuberal region of the hypothalamus, TH-immunoreactive neurons were found in the paraventricular nucleus, dorsomedial hypothalamic nucleus, zona incerta and arcuate nucleus. In the caudal tuberal region of the hypothalamus, dorsal hypothalamic nucleus, posterior hypothalamic complex and arcuate nucleus.

Efeito da deaferentaçäo hipotalâmica anterior no processo de reparo alveolar em ratos: estudo histológico / The effects of anterior hypothalamic deafferentation on tooth extraction healing in rats: histological study

Para determinar o papel das estruturas extra-hipotalâmicas nas diversas fases do processo de reparo do osso alveolar, ratos machos adultos com deaferentaçäo hipotalâmica anterior (DHA) foram submetidos à extraçäo dental e sacrificados após 3, 6, 9, 12 e 21 dias. As maxilas foram removidas e submetidas ao estudo histológico. A análise do estudo histológico demonstrou que a DHA: 1) näo interferiu na formaçäo do coágulo na fase inicial; 2) aumentou a permanência do coágulo e do tecido de granulaçäo; 3) interferiu no processo de mineralizaçäo do tecido neoformado, induzindo um retardo no processo de reparo alveolar. Nossos resultados confirmam o envolvimento do eixo neuroendócrino e demonstraram pela primeira vez a importância das vias extra-hipotalâmicas nos mecanismos que envolvem o processo de reparo do osso alveolar após a extraçäo dental em ratos

Response of Hypothalamic Hypophyseal Hormones to Stimulation and Lesion in the Thalamus and Hypothalamus

Plasma levels of growth hormone(GH), luteinizing hormone(LH) and cortisol were determined by radioimmunoassay following radiofrequency(RF) stimulation or coagulation of various nuclei in thalamus and hypothalamus. RF stimulation or coagulation of many nuclei in thalamus and hypothalamus consisted of pulvinar and dorsomedial nucleus in thalamus and anterior and posterior hypothalamic nuclei in hypothalamus. Anterior thalamic stimulation resulted in highly significant increase of plasma LH, GH, cortisol and TH levels. However thalamic stimulation resulted no change in the level of various plasma hormones. Hypothalamic lesion produced significantly decreased plasma LH, GH and cortisol levels. Plasma cortisol and LH levels were highest 2 hours after stimulation while GH levels did not increased until 6 hours and TH until 72 hours respectively after stimulation. The significant difference in latency for beginning of hormone secretion suggests that GH, cortisol and LH may be controlled by several separate neuronal networks. Plasma GH and cortisol levels were lowest 72 hrs after coagulation of the anterior hypothalamic area, while GH, cortisol and LH levels did not change following stimulation or coagulation of posterior hypothalamic nucleus and thalamic nucldi. It was also noted that the anterior hypothalamic stimulation or coagulation caused increased or decreased in GH, cortisol, and LH than that observed from stimulation or coagulation of other hypothalamic and thalamic nuclei respectively.