Circadian variation in the activity of the 5‐HT<sub>1B</sub> autoreceptor in the region of the suprachiasmatic nucleus, measured by microdialysis in the conscious freely‐moving rat

Garabette, Martine L.; Martin, Keith F.; Redfern, P. H.

doi:10.1038/sj.bjp.0703753

Cited by 11 publications

(5 citation statements)

References 39 publications

(47 reference statements)

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“…Finally, both LD and DD 5HT/5HIAA ratios, used as index of serotonin neuronal activity, were higher during the day than during the night, in relation to Arvicanthis activity state, 84 in accordance with Cuesta and colleagues 40 . A similar correlation with arousal has been shown in nocturnal rodents, where 5HT and 5HIAA content and release in the SCN is rhythmic and presents a peak at the beginning of the night (onset of activity) 29,85,86 . Serotonin and 5HIAA rhythms are therefore in antiphase between nocturnal and diurnal rodents.…”

Section: Discussionsupporting

confidence: 85%

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Bimodal serotonin synthesis in the diurnal rodent, Arvicanthis ansorgei

et al. 2022

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In mammals, behavioral activity is regulated both by the circadian system, orchestrated by the suprachiasmatic nucleus (SCN), and by arousal structures, including the serotonergic system. While the SCN is active at the same astronomical time in diurnal and nocturnal species, little data are available concerning the serotonergic (5HT) system in diurnal mammals. In this study, we investigated the functioning of the 5HT system, which is involved both in regulating the sleep/wake cycle and in synchronizing the SCN, in a diurnal rodent, Arvicanthis ansorgei. Using in situ hybridization, we characterized the anatomical extension of the raphe nuclei and we investigated 24 h mRNA levels of the serotonin rate‐limiting enzyme, tryptophan hydroxylase 2 (tph2). Under both 12 h:12 h light/dark (LD) and constant darkness (DD) conditions, tph2 mRNA expression varies significantly over 24 h, displaying a bimodal profile with higher values around the (projected) light transitions. Furthermore, we considered several SCN outputs, namely melatonin, corticosterone, and locomotor activity. In both LD and DD, melatonin profiles display peak levels during the biological night. Corticosterone plasma levels show a bimodal rhythmic profile in both conditions, with higher levels preceding the two peaks of Arvicanthis locomotor activity, occurring at dawn and dusk. These data demonstrate that serotonin synthesis in Arvicanthis is rhythmic and reflects its bimodal behavioral phenotype, but differs from what has been previously described in nocturnal species.

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Section: Discussionsupporting

confidence: 85%

“…40 A similar correlation with arousal has been shown in nocturnal rodents, where 5HT and 5HIAA content and release in the SCN is rhythmic and presents a peak at the beginning of the night (onset of activity). 29,85,86 Serotonin and 5HIAA rhythms are therefore in antiphase between nocturnal and diurnal rodents.…”

Section: Arvicanthismentioning

confidence: 99%

Bimodal serotonin synthesis in the diurnal rodent, Arvicanthis ansorgei

et al. 2022

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“…As the rate of 5-HT synthesis increases during the light phase (Hery et al, 1972), it is likely that the ability of MDMA to induce 5-HT release peaks during the light phase of the diurnal cycle. There is also evidence that the sensitivity of 5-HT 1B receptors, as well as the density of 5-HT 1 binding sites, increases during the light phase (Akiyoshi et al, 1989; Garabette et al, 2000). These diurnal fluctuations in serotonergic transmission could reduce the sensitivity of MDMA locomotor-activating effects to habituation.…”

Section: Discussionmentioning

confidence: 99%

Differences in the locomotor-activating effects of indirect serotonin agonists in habituated and non-habituated rats

Halberstadt

Buell

Price

et al. 2012

Pharmacology Biochemistry and Behavior

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The indirect serotonin (5-HT) agonist 3,4-methylenedioxymethamphetamine (MDMA) produces a distinct behavioral profile in rats consisting of locomotor hyperactivity, thigmotaxis, and decreased exploration. The indirect 5-HT agonist α-ethyltryptamine (AET) produces a similar behavioral profile. Using the Behavioral Pattern Monitor (BPM), the present investigation examined whether the effects of MDMA and AET are dependent on the novelty of the testing environment. These experiments were conducted in Sprague-Dawley rats housed on a reversed light cycle and tested during the dark phase of the light/dark cycle. We found that racemic MDMA (RS-MDMA; 3 mg/kg, SC) increased locomotor activity in rats tested in novel BPM chambers, but had no effect on locomotor activity in rats habituated to the BPM chambers immediately prior to testing. Likewise, AET (5 mg/kg, SC) increased locomotor activity in non-habituated animals but not in animals habituated to the test chambers. These results were unexpected because previous reports indicate that MDMA has robust locomotor-activating effects in habituated animals. To further examine the influence of habituation on MDMA-induced locomotor activity, we conducted parametric studies with S-(+)-MDMA (the more active enantiomer) in habituated and non-habituated rats housed on a standard or reversed light cycle. Light cycle was included as a variable due to reported differences in sensitivity to serotonergic ligands during the dark and light phases. In confirmation of our initial studies, rats tested during the dark phase and habituated to the BPM did not show an S-(+)-MDMA (3 mg/kg, SC)-induced increase in locomotor activity, whereas non-habituated rats did. By contrast, in rats tested during the light phase, S-(+)-MDMA increased locomotor activity in both non-habituated and habituated rats, although the response in habituated animals was attenuated. The finding that habituation and light cycle interact to influence MDMA- and AET-induced hyperactivity demonstrates that there are previously unrecognized complexities associated with the behavioral effects of these drugs.

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“…Circadian rhythms in receptor function and density have been reported for a number of different receptors in animal models. The density of β‐adrenoceptors (10), α1‐adrenoceptors (11), expression of μ‐opioid receptors (12), and the functional activity of 5‐HT 1B autoreceptors (13) have all been found to vary over a 24‐h period.…”

Section: Evidence For Time‐of‐day Changes In Pk and Pd In Adultsmentioning

confidence: 99%

Circadian rhythms and their development in children: implications for pharmacokinetics and pharmacodynamics in anesthesia

Potts

Cheeseman

Warman

2011

Pediatric Anesthesia

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The influence of time-of-day on the action and toxicity of drugs may be an important factor in the design of pharmacokinetic (PK) and pharmacodynamic (PD) studies, and the interpretation of data resulting from these studies. Time-of-day can have a profound influence on the action of drugs. In some settings (e.g. cancer chemotherapy), the timing of drug administration has been utilized to maximize therapeutic effect and minimize toxicity. Time-of-day variation in the action of anesthetic drugs has been clearly demonstrated in adults. For example, local anesthetic action is longest during the afternoon, and neuromuscular blockade by rocuronium lasts one-third longer in the morning than the afternoon. Circadian rhythms develop over the first months and years of life. Robust rhythms in hormone production (e.g. melatonin and cortisol) are seen at approximately 3 months of age, but it remains unclear as to when daily rhythms in drug PK and PD first appear. Here, we review the evidence for time-of-day effects in anesthetic drugs in adults and children and outline the potential influence this has on pediatric anesthesia.

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Circadian variation in the activity of the 5‐HT_1B autoreceptor in the region of the suprachiasmatic nucleus, measured by microdialysis in the conscious freely‐moving rat

Cited by 11 publications

References 39 publications

Bimodal serotonin synthesis in the diurnal rodent, Arvicanthis ansorgei

Bimodal serotonin synthesis in the diurnal rodent, Arvicanthis ansorgei

Differences in the locomotor-activating effects of indirect serotonin agonists in habituated and non-habituated rats

Circadian rhythms and their development in children: implications for pharmacokinetics and pharmacodynamics in anesthesia

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Circadian variation in the activity of the 5‐HT1B autoreceptor in the region of the suprachiasmatic nucleus, measured by microdialysis in the conscious freely‐moving rat

Cited by 11 publications

References 39 publications

Bimodal serotonin synthesis in the diurnal rodent, Arvicanthis ansorgei

Bimodal serotonin synthesis in the diurnal rodent, Arvicanthis ansorgei

Differences in the locomotor-activating effects of indirect serotonin agonists in habituated and non-habituated rats

Circadian rhythms and their development in children: implications for pharmacokinetics and pharmacodynamics in anesthesia

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Circadian variation in the activity of the 5‐HT_1B autoreceptor in the region of the suprachiasmatic nucleus, measured by microdialysis in the conscious freely‐moving rat