Extensive juvenile “babysitting” facilitates later adult maternal responsiveness, decreases anxiety, and increases dorsal raphe tryptophan hydroxylase-2 expression in female laboratory rats

Tryptophan hydroxylase-2 mRNA (TPH, the rate limiting enzyme in 5-HT synthesis) expression levels display circadian variations in the median and dorsal raphe nuclei. This circadian pattern is under the control of the suprachiasmatic nuclei (SCN), the master clock. Photoperiodic cue is encoded by the SCN which convey the seasonal message to target sites. In the present study, we have investigated the effect of photoperiodic changes on the serotonergic neurones of the raphe nuclei. We have assessed the daily expression of TPH2 mRNA in both median and dorsal raphe nuclei of rats housed either under long photoperiod (18 h light/6 h dark cycle, LP18:6) or short photoperiod (SP6:18). Our results demonstrate that under LP18:6, TPH2 mRNA levels display a progressive decrease during the dark period and a maximal expression is reported at the beginning of the light period. The expression pattern of TPH2 mRNA under SP6:18 remains unchanged during the dark period and increases significantly before the day/night transition. This latter expression pattern is in line with the daily profiles of TPH2 mRNA reported previously under standard lighting regimen (12 h light/12 h dark cycle). The present results suggest that TPH2 mRNA expression pattern within DR and MR is affected by photoperiod which might in turn affect TPH content and 5HT release within the circadian structures, but also in all the serotonergic projection areas of the brain.

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Ultrastructural characterization of tryptophan hydroxylase 2-specific cortical serotonergic fibers and dorsal raphe neuronal cell bodies after MDMA treatment in rat

Psychopharmacology ◽

10.1007/s00213-010-2041-2 ◽

2010 ◽

Vol 213 (2-3) ◽

pp. 377-391 ◽

Cited By ~ 14

Author(s):

Csaba Ádori ◽

Péter Lőw ◽

Rómeó D. Andó ◽

Lise Gutknecht ◽

Dorottya Pap ◽

...

Keyword(s):

Tryptophan Hydroxylase ◽

Neuronal Cell ◽

Dorsal Raphe ◽

Tryptophan Hydroxylase 2 ◽

Neuronal Cell Bodies ◽

Ultrastructural Characterization ◽

Dorsal Raphé

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Dorsal raphe serotonin neurotransmission is required for the expression of nursing behavior and for pup survival

Scientific Reports ◽

10.1038/s41598-021-84368-6 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Aude Muzerelle ◽

Mariano Soiza-Reilly ◽

Cornelia Hainer ◽

Pierre-Louis Ruet ◽

Klaus-Peter Lesch ◽

...

Keyword(s):

Tryptophan Hydroxylase ◽

Dorsal Raphe ◽

Normal Mammary Gland ◽

Knock Out ◽

Maternal Experience ◽

Pup Retrieval ◽

Pup Survival ◽

Gland Development ◽

Severe Growth ◽

Dorsal Raphé

AbstractProper maternal care is an essential factor of reproductive success in mammals, involving a repertoire of behaviors oriented toward the feeding and care of the offspring. Among the neurotransmitters involved in the initiation of these behaviors, serotonin (5-HT) seems to play an important role. Here we compared pup-oriented maternal behaviors in mice with constitutive 5-HT depletion, the tryptophan hydroxylase 2-knock-out (Tph2-KO) and the Pet1-KO mice. We report that the only common pup-oriented defect in these 2 hyposerotoninergic models is a defective nursing in parturient mice and altered nursing-like (crouching) behavior in virgin mice, while pup retrieval defects are only present in Tph2-KO. Despite a normal mammary gland development and milk production, the defect in appropriate nursing is responsible for severe growth retardation and early lethality of pups born to hyposerotonergic dams. This nursing defect is due to acute rather constitutive 5-HT depletion, as it is reproduced by adult knockdown of Tph2 in the dorsal raphe nucleus in mothers with a prior normal maternal experience. We conclude that 5-HT innervation from the dorsal raphe is required for both the initiation and maintenance of a normal nursing behavior. Our findings may be related to observations of reduced maternal/infant interactions in human depression.

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