Light stimulation during postnatal development is not determinant for glutamatergic neurotransmission from the retinohypothalamic tract to the suprachiasmatic nucleus in rats
| Autor: | Ricardo A. Navarro-Polanco, Javier Alamilla, Miriam E. Reyes-Mendez, Eloy G. Moreno-Galindo, Néstor Mendoza-Muñoz, J. Manuel Herrera-Zamora, Fernando Osuna-Lopez, José L. Góngora-Alfaro |
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| Rok vydání: | 2021 |
| Předmět: |
medicine.medical_specialty
Light Biology Neurotransmission Synaptic Transmission 03 medical and health sciences Glutamatergic 0302 clinical medicine Postsynaptic potential Internal medicine medicine Animals Suprachiasmatic Nucleus Neurons Circadian rhythm 030304 developmental biology 0303 health sciences Developmental maturation Suprachiasmatic nucleus General Neuroscience Excitatory Postsynaptic Potentials Circadian Rhythm Rats Endocrinology nervous system Excitatory postsynaptic potential Suprachiasmatic Nucleus 030217 neurology & neurosurgery Retinohypothalamic tract |
| Zdroj: | The European journal of neuroscienceREFERENCES. 54(2) |
| ISSN: | 1460-9568 |
| Popis: | The hypothalamic suprachiasmatic nucleus (SCN) is the leading circadian pacemaker in mammals, which synchronizes with environmental light through the retinohypothalamic tract (RHT). Although the SCN regulates circadian rhythms before birth, postnatal synaptic changes are needed for the RHT-SCN pathway to achieve total functional development. However, it is unknown whether visual experience affects developmental maturation. Here, we studied the effects of constant darkness (DD) rearing on the physiology (at pre- and postsynaptic levels) of glutamatergic neurotransmission between RHT and SCN during postnatal development in rats. Upon recording spontaneous and evoked excitatory postsynaptic currents (EPSCs) by electrical stimulation of RHT fibers, we found that DD animals at early postnatal ages (P3-19) exhibited different frequencies of spontaneous EPSCs and lower synaptic performance (short-term depression, release sites, and recruitment of RHT fibers) when compared with their normal light/dark (LD) counterparts. At the oldest age evaluated (P30-35), there was a synaptic response strengthening (probability of release, vesicular re-filling rate, and reduced synaptic depression) in DD rats, which functionally equaled (or surmounted) that of LD animals. Control experiments evaluating EPSCs in ventral SCN neurons of LD rats during day and night revealed no significant differences in spontaneous or evoked EPSCs by high-frequency trains in the RHT at any postnatal age. Our results suggest that DD conditions induce a compensatory mechanism in the glutamatergic signaling of the circadian system to increase the chances of synchronization to light at adult ages, and that the synaptic properties of RHT terminals during postnatal development are not critically influenced by environmental light. |
| Databáze: | OpenAIRE |
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