The rise and fall of pineal <i>N</i>‐acetyltransferase <i>in vitro</i>: Neural regulation in the developing rat

Brammer, Mildred; Binkley, Sue; Mosher, Karen

doi:10.1002/neu.480130604

Cited by 4 publications

(1 citation statement)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Unilateral or bilateral surgical removal of the SCG was performed at 9am (ZT3), as described previously (Brammer et al, 1982). In brief, animals were anesthetized with isoflurane, a small incision of cca.…”

Section: Methodsmentioning

confidence: 99%

Transsynaptic Activity-Dependent Regulation of Axon Branching and Neurotrophin ExpressionIn Vivo

Calinescu¹,

Liu²,

Wang³

et al. 2011

J. Neurosci.

View full text Add to dashboard Cite

The two major classes of activity-dependent neuroplasticity predict different consequences of activity alteration on circuit response. Hebbian plasticity (positive feedback) posits that alteration of neuronal activity causes a parallel response within a circuit. In contrast, homeostatic plasticity (negative feedback) predicts that altering neuronal activity results in compensatory responses within a circuit. The relative roles of these modes of plasticity in vivo are unclear, since neuronal circuits are difficult to manipulate in the intact organism. In this study, we tested the in vivo effects of activity deprivation in the superior cervical ganglion-pineal circuit of adult rats, which can be non-invasively silenced by exposing animals to constant light. We demonstrated that total deprivation of sympathetic activity markedly decreased the presence of axonal proteins in the pineal and reduced the density and thickness of sympathetic axonal arbors. In addition, we demonstrated that sympathetic inactivity eliminated pineal function and markedly decreased pineal expression of neurotrophins. Administration of β-adrenergic agonist restored the expression of pre- and post-synaptic proteins. Furthermore, compensatory axonal growth through collateral sprouting, normally seen following unilateral denervation of the pineal, was profoundly impaired in the absence of neural activity. Thus, these data suggest that sympathetic axonal terminals are maintained by neural activity that induces neurotrophins, which may act through a retrograde mechanism to preserve the integrity of axonal arbors via a positive feedback loop. Conversely, silent yet intact circuits enter a “hibernation mode” marked by reduction of presynaptic axonal structures and dramatically reduced postsynaptic expression of neurotrophins, by utilizing Hebbian-like neuroplasticity.

show abstract

Section: Methodsmentioning

confidence: 99%

Transsynaptic Activity-Dependent Regulation of Axon Branching and Neurotrophin ExpressionIn Vivo

Calinescu¹,

Liu²,

Wang³

et al. 2011

J. Neurosci.

View full text Add to dashboard Cite

show abstract

Entrainment of the circadian rhythms of blinded infant rats by nursing mothers

Takahashi

Deguchi

1983

Physiology & Behavior

View full text Add to dashboard Cite

Lower Tryptophan:Phenylalanine Ratios in Culture Media Increase Medium: Pineal Melatonin Ratios in Early Dark but not Late Light Phase

Catalá

Quay

Timiras

1987

Journal of Pineal Research

View full text Add to dashboard Cite

Pineals from male Long-Evans rats (60-65 days old; adapted to a 0700-1900 photoperiod) were cultured for 6 h either in light (1200-1800) or in dark (1800-2400). The objective was to ascertain the effects of tryptophan (trp) and phenylalanine (phe) levels and ratios in the culture medium on melatonin levels in the pineals and their respective media. Total culture (pineal + medium) melatonin levels, determined by RIA, were similar under all conditions. However, in cultures during the early dark phase (1800-2400) lower trp:phe ratios in the medium led to lower pineal:medium ratios of melatonin content. In cultures during the late light phase (1200-1800) the trp:phe ratio had little impact on the pineal:medium distribution of melatonin. Trp:phe ratio rather than absolute level of either amino acid appeared responsible for this effect. Functionally this means that during early dark phase, but not late light phase, movement of melatonin from cultured pineal to medium is progressively facilitated by lower trp:phe ratios. It remains to be determined to what extent darkness per se and/or endogenous pineal rhythmic mechanisms have a permissive role in the action of trp:phe ratio on pineal melatonin release. A melatonin compartmentalization/release effect of these or other amino acids, or their ratios, has not been reported previously and may possibly contribute to mechanisms for melatonin's transport or release at night.

show abstract

The rise and fall of pineal N‐acetyltransferase in vitro: Neural regulation in the developing rat

Cited by 4 publications

References 16 publications

Transsynaptic Activity-Dependent Regulation of Axon Branching and Neurotrophin ExpressionIn Vivo

Transsynaptic Activity-Dependent Regulation of Axon Branching and Neurotrophin ExpressionIn Vivo

Entrainment of the circadian rhythms of blinded infant rats by nursing mothers

Lower Tryptophan:Phenylalanine Ratios in Culture Media Increase Medium: Pineal Melatonin Ratios in Early Dark but not Late Light Phase

Contact Info

Product

Resources

About