NE Cell Research Articles

Brain norepinephrine and metabolites after treadmill training and wheel running in rats.

Regional changes in concentrations of brain norepinephrine [NE] and its metabolites after chronic exercise have not been described for exercise protocols not confounded by other stressors. We examined levels of [NE], 3-methoxy-4-hydroxyphenylglycol [MHPG], and 3,4-dihydroxyphenylglycol [DHPG] in the frontal cortex, hippocampus, pons-medulla, and spinal cord after 8 wk of exercise. Male Sprague-Dawley rats (N = 36) were randomly assigned to three conditions: 1) 24-h access to activity wheel running (WR), 2) treadmill running (TR) at 0 degrees incline for 1 h.d-1 at 25-30 m.min-1, or 3) a sedentary control group (C). Levels (nmol.g-1) of [NE], [MHPG], and [DHPG] were assayed by high performance liquid chromatography with electrochemical detection. Planned contrasts (P < 0.05) indicated that exercise training increased succinate dehydrogenase activity (mmol cytochrome C reduced.min-1.g-1 wet weight) in soleus muscle for TR compared with WR or C. [NE] was higher in the pons-medulla and spinal cord for both TR and WR compared with C. [DHPG] was higher in the pons-medulla for TR compared with C, and [MHPG] was higher in the frontal cortex and in the hippocampus for TR compared with C. Our results suggest that treadmill exercise training is accompanied by brain noradrenergic adaptations consistent with increased metabolism of NE in areas containing NE cell bodies and ascending terminals, whereas treadmill running and wheel running are accompanied by increases in levels of NE in the areas of NE cell bodies and the spinal cord, independently of an exercise training effect.

Possible precursors to new hair cells, support cells, and Schwann cells in the ear of a post-embryonic fish

The sources of new hair cells, support cells, and Schwann cells were identified in the statoacoustic end organs of normal post-embryonic fish ( Astronotus ocellatus). S-phase cells, defined as cells that take up 3H-thymidine in preparation for mitosis, and their progeny were visualized using autoradiography. Two types of S-phase cells were found: ‘embryonic-like neuroepithelial’ (NE) cells and ‘basally located S-phase’ (BLS) cell. The NE cells had elongated nuclei and processes extending basally and apically. Thirty minutes after the thymidine injection labeled NE cell nuclei were found between hair cell nuclei and support cell nuclei. After two and four hours survival some labeled NE nuclei were closer to the lumen, where they divided. One labeled support cell was seen after four hours survival and one labeled hair cell after nine hours survival. Significant numbers of labeled support and hair cells were not seen until 24 h survival. These results led us to identify NE cells as the immediate source of new hair cells and support cells. The BLS cells had small nuclei with little surrounding cytoplasm. Shortly after the thymidine injection BLS cells were found between the hair cell nuclei and the basement membrane, and they underwent mitosis in this position. The BLS cells resemble intra-epithelial Schwann cells, except that they are not curved around axonal profiles. We suggest that the BLS cells are Schwann cell precursors.

The role of the brain catecholaminergic system in the control of gonadotropin secretion. II. The involvement of the brain stem in the control of gonadotropin secretion (author's transl)

The studies on the role of the midbrain ascending pathways in the proestrous surges of gonadotropin and PRL have recently appeared, suggesting the importance of monoamine pathways in this process. In the preceeding study, it was suggested that the ascending noradrenergic system plays a stimulatory role in the induction of preovulatory surges of gonadotropin and PRL. The purpose of the present study was to investigate the noradrenergic mechanisms in the lower brain stem which are involved in preovulatory surges of gonadotropin and PRL.Adult female rats of Wistar strain served as experimental animals. Each surgical operation was stereotaxically performed under ether anesthesia. Blood samples were collected without anestheisa through the indwelling atraial cannulae for the determination of serum LH, FSH and PRL by radioimmunoassay.(1) The bilateral electrolytic lesions, which were made in the ventrolateral part of the medulla oblongata at 1100-1330 h on proestrus, blocked ovulation in 5 out of 7 animals (p<0.05) and significantly suppressed the proestrous surges of serum LH, FSH and PRL when compared to the sham-lesioned animals, while the lesions made in the dorsomedial part of the medulla oblongata blocked ovulation in only 1 out of 5 animals.(2) The bilateral implants of diethyldithiocarbamate (DDC), an inhibitor of norepinephrine synthesis, into the ventrolateral part of the medulla oblongata, which were made at 1100-1330 h on proestrus, blocked ovulation in 6 out of 9 animals (p<0.05) and significantly suppressed the proestrous surges of serum LH and FSH, while the DDC implants into the dorsomedial part of the medulla oblongata blocked ovulation in only 1 out of 5 animals.(3) The unilateral implants of ovarian steroids (estradiol benzoate or progesterone) into the ventrolateral part of the medulla oblongata failed to increase or decrease serum LH, FSH and PRL values at least within 6 hours in the ovariectomized, estrogen-primed rats.(4) The unilateral electrochemical stimulations of the ventrolateral part of the medulla oblongata failed to induce ovulation and the surges of serum LH and FSH in the pentobarbital-blocked proestrous rats, although the stimulations slightly suppressed the serum PRL value.The present study suggests that the ventrolateral part of the medulla oblongata is involved in the induction of the proestrous surges of LH, FSH and PRL. The finding that the DDC implants into the ventrolateral part of the medulla oblongata significantly suppressed the proestrous surges of LH and FSH indicates that the noradrenergic system arising in the Al NE cell group may play an important role in the induction of the proestrous gonadotropin surge. However, the induction of the gonadotropin surge was not obtained from the implants of ovarian steroids into, nor the electrochemical stimulations of, the ventrolateral part of the medulla oblongata.

Conditions for adrenergic hyperinnervation in hippocampus: II. Electrophysiological evidence from intraocular double grafts.

Following sequential intraocular transplantations of areas containing NE cell bodies (locus coeruleus or superior cervical ganglion) and of NE fiber target areas (hippocampus), both pieces mature in a manner analogous to that observed for individual transplants. NE-containing nerve fibers, derived from either LC or SCG transplants, can be seen to invade the hippocampal formation. When LC is used, the invading fibers markedly hyperinnervate the hippocampus while SCG-derived fiber densities approximate those seen with innervation from the adrenergic ground plexus of the iris. Electrophysiological recordings from neurons in the LC reveal an atropine-sensitive excitatory response to illumination, suggesting innervation of the LC by cholinergic nerve fibers from the iris. This is supported by the fact that dense cholinesterase-positive staining can be found in the LC piece. Application of an epileptogenic agent, such as penicillin, results in a marked excitation of neurons in the LC without inducing epileptiform activity in the hippocampus. In contrast, single hippocampal grafts seize readily after penicillin. Local application of the inhibitory agent GABA into the LC allows penicillin-induced epileptiform activity to generate in the hippocampus, suggesting that functional inhibitory innervation develops between NE fibers derived from LC and pyramidal neurons in the hippocampus. Supporting this, subsequent excitation of LC neurons by iontophoresis of glutamate terminates the hippocampal seizure. Prior administration of reserpine (2.5 mg/kg) disrupts the inhibitory influence of LC innervation on the hippocampal EEG following penicillin. After reserpine, the hippocampal portions of double grafts behave like single hippocampal transplants. It is concluded that sequential transplantations of cell body and target regions of the CNS to the anterior chamber of the eye creates a functional, yet isolated, neuronal pathway which can be utilized to study the development of neuronal connections.

Hysteresis effects in the mode locking of a He-Ne laser by a Ne discharge cell

We have observed the existence of hysteresis effects associated with the mode locking of a He-Ne laser operating at 6328 Å by a Ne cell when appropriate excitations, losses, lengths, and positions of both laser tube and Ne cell are chosen. The hysteresis effects manifest themselves in the pulsing rate, the pulse-width, and the power output.