Limits...
Cannabinoid type-1 receptor signaling in central serotonergic neurons regulates anxiety-like behavior and sociability.

Häring M, Enk V, Aparisi Rey A, Loch S, Ruiz de Azua I, Weber T, Bartsch D, Monory K, Lutz B - Front Behav Neurosci (2015)

Bottom Line: A functional interaction between eCBs and the serotonergic system has already been suggested.Previously, we showed that cannabinoid type-1 (CB1) receptor mRNA and protein are localized in serotonergic neurons of the raphe nuclei, implying that the eCB system can modulate serotonergic functions.In order to substantiate the physiological role of the CB1 receptor in serotonergic neurons of the raphe nuclei, we generated serotonergic 5-hydroxytryptamine (5-HT) neuron-specific CB 1 receptor-deficient mice, using the Cre/loxP system with a tamoxifen-inducible Cre recombinase under the control of the regulatory sequences of the tryptophan hydroxylase 2 gene (TPH2-CreER (T2)), thus, restricting the recombination to 5-HT neurons of the central nervous system (CNS).

View Article: PubMed Central - PubMed

Affiliation: Institute of Physiological Chemistry, University Medical Center of the Johannes Gutenberg University Mainz, Germany.

ABSTRACT
The endocannabinoid (eCB) system possesses neuromodulatory functions by influencing the release of various neurotransmitters, including γ-aminobutyric acid (GABA) and glutamate. A functional interaction between eCBs and the serotonergic system has already been suggested. Previously, we showed that cannabinoid type-1 (CB1) receptor mRNA and protein are localized in serotonergic neurons of the raphe nuclei, implying that the eCB system can modulate serotonergic functions. In order to substantiate the physiological role of the CB1 receptor in serotonergic neurons of the raphe nuclei, we generated serotonergic 5-hydroxytryptamine (5-HT) neuron-specific CB 1 receptor-deficient mice, using the Cre/loxP system with a tamoxifen-inducible Cre recombinase under the control of the regulatory sequences of the tryptophan hydroxylase 2 gene (TPH2-CreER (T2)), thus, restricting the recombination to 5-HT neurons of the central nervous system (CNS). Applying several different behavioral paradigms, we revealed that mice lacking the CB1 receptor in serotonergic neurons are more anxious and less sociable than control littermates. Thus, we were able to show that functional CB1 receptor signaling in central serotonergic neurons modulates distinct behaviors in mice.

No MeSH data available.


Related in: MedlinePlus

Tamoxifen-inducible genetic inactivation of cannabinoid type 1 (CB1) receptor in TPH2-positive neurons. (A) Schematic illustrations of CB1fl/fl allele before (above) and after Cre recombinase-mediated recombination (below). Arrows indicate primer positions. (B) Applying primers G50/G53, polymerase chain reaction (PCR) reactions were run using genomic DNA from the raphe nuclei region as a template. The 600 bp band indicating successful recombination was only detected in mice containing the CreERT2 transgene. (Cre+) after treatment with tamoxifen (+Tam). LA, left homology arm; RA, right homology arm; Cre+, animals heterozygous for the CreERT2 transgene and homozygous for the CB1fl/fl allele. Cre- = CB1fl/fl mice without the CreERT2 transgene; +Tam, tamoxifen-treated; −Tam, vehicle-treated; M, DNA size marker.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4558975&req=5

Figure 1: Tamoxifen-inducible genetic inactivation of cannabinoid type 1 (CB1) receptor in TPH2-positive neurons. (A) Schematic illustrations of CB1fl/fl allele before (above) and after Cre recombinase-mediated recombination (below). Arrows indicate primer positions. (B) Applying primers G50/G53, polymerase chain reaction (PCR) reactions were run using genomic DNA from the raphe nuclei region as a template. The 600 bp band indicating successful recombination was only detected in mice containing the CreERT2 transgene. (Cre+) after treatment with tamoxifen (+Tam). LA, left homology arm; RA, right homology arm; Cre+, animals heterozygous for the CreERT2 transgene and homozygous for the CB1fl/fl allele. Cre- = CB1fl/fl mice without the CreERT2 transgene; +Tam, tamoxifen-treated; −Tam, vehicle-treated; M, DNA size marker.

Mentions: Deletion of the CB1 receptor gene in TPH2-CB1−/− mice was detected only in genomic DNA isolated from the area of the raphe nuclei, but not from other brain regions or duodenum (Bellocchio et al., 2013), indicating a region-specific loss of the CB1 receptor gene. Therefore, we have isolated genomic DNA from brain punches of the raphe nuclei region of tamoxifen-treated and vehicle-treated TPH2-CB1−/− and TPH2-CB1+/+ mice, respectively. Using primers located on the left and right homology arms (G50 and G53; Figure 1A), incidence of successful recombination events was tested by the presence of a 600 bp band. We were only able to detect this band in mice that expressed Cre recombinase in 5-HT neurons (TPH2-CB1−/−) and were treated with tamoxifen (Figure 1B), indicating the absence of background recombination without tamoxifen treatment in these mice.


Cannabinoid type-1 receptor signaling in central serotonergic neurons regulates anxiety-like behavior and sociability.

Häring M, Enk V, Aparisi Rey A, Loch S, Ruiz de Azua I, Weber T, Bartsch D, Monory K, Lutz B - Front Behav Neurosci (2015)

Tamoxifen-inducible genetic inactivation of cannabinoid type 1 (CB1) receptor in TPH2-positive neurons. (A) Schematic illustrations of CB1fl/fl allele before (above) and after Cre recombinase-mediated recombination (below). Arrows indicate primer positions. (B) Applying primers G50/G53, polymerase chain reaction (PCR) reactions were run using genomic DNA from the raphe nuclei region as a template. The 600 bp band indicating successful recombination was only detected in mice containing the CreERT2 transgene. (Cre+) after treatment with tamoxifen (+Tam). LA, left homology arm; RA, right homology arm; Cre+, animals heterozygous for the CreERT2 transgene and homozygous for the CB1fl/fl allele. Cre- = CB1fl/fl mice without the CreERT2 transgene; +Tam, tamoxifen-treated; −Tam, vehicle-treated; M, DNA size marker.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4558975&req=5

Figure 1: Tamoxifen-inducible genetic inactivation of cannabinoid type 1 (CB1) receptor in TPH2-positive neurons. (A) Schematic illustrations of CB1fl/fl allele before (above) and after Cre recombinase-mediated recombination (below). Arrows indicate primer positions. (B) Applying primers G50/G53, polymerase chain reaction (PCR) reactions were run using genomic DNA from the raphe nuclei region as a template. The 600 bp band indicating successful recombination was only detected in mice containing the CreERT2 transgene. (Cre+) after treatment with tamoxifen (+Tam). LA, left homology arm; RA, right homology arm; Cre+, animals heterozygous for the CreERT2 transgene and homozygous for the CB1fl/fl allele. Cre- = CB1fl/fl mice without the CreERT2 transgene; +Tam, tamoxifen-treated; −Tam, vehicle-treated; M, DNA size marker.
Mentions: Deletion of the CB1 receptor gene in TPH2-CB1−/− mice was detected only in genomic DNA isolated from the area of the raphe nuclei, but not from other brain regions or duodenum (Bellocchio et al., 2013), indicating a region-specific loss of the CB1 receptor gene. Therefore, we have isolated genomic DNA from brain punches of the raphe nuclei region of tamoxifen-treated and vehicle-treated TPH2-CB1−/− and TPH2-CB1+/+ mice, respectively. Using primers located on the left and right homology arms (G50 and G53; Figure 1A), incidence of successful recombination events was tested by the presence of a 600 bp band. We were only able to detect this band in mice that expressed Cre recombinase in 5-HT neurons (TPH2-CB1−/−) and were treated with tamoxifen (Figure 1B), indicating the absence of background recombination without tamoxifen treatment in these mice.

Bottom Line: A functional interaction between eCBs and the serotonergic system has already been suggested.Previously, we showed that cannabinoid type-1 (CB1) receptor mRNA and protein are localized in serotonergic neurons of the raphe nuclei, implying that the eCB system can modulate serotonergic functions.In order to substantiate the physiological role of the CB1 receptor in serotonergic neurons of the raphe nuclei, we generated serotonergic 5-hydroxytryptamine (5-HT) neuron-specific CB 1 receptor-deficient mice, using the Cre/loxP system with a tamoxifen-inducible Cre recombinase under the control of the regulatory sequences of the tryptophan hydroxylase 2 gene (TPH2-CreER (T2)), thus, restricting the recombination to 5-HT neurons of the central nervous system (CNS).

View Article: PubMed Central - PubMed

Affiliation: Institute of Physiological Chemistry, University Medical Center of the Johannes Gutenberg University Mainz, Germany.

ABSTRACT
The endocannabinoid (eCB) system possesses neuromodulatory functions by influencing the release of various neurotransmitters, including γ-aminobutyric acid (GABA) and glutamate. A functional interaction between eCBs and the serotonergic system has already been suggested. Previously, we showed that cannabinoid type-1 (CB1) receptor mRNA and protein are localized in serotonergic neurons of the raphe nuclei, implying that the eCB system can modulate serotonergic functions. In order to substantiate the physiological role of the CB1 receptor in serotonergic neurons of the raphe nuclei, we generated serotonergic 5-hydroxytryptamine (5-HT) neuron-specific CB 1 receptor-deficient mice, using the Cre/loxP system with a tamoxifen-inducible Cre recombinase under the control of the regulatory sequences of the tryptophan hydroxylase 2 gene (TPH2-CreER (T2)), thus, restricting the recombination to 5-HT neurons of the central nervous system (CNS). Applying several different behavioral paradigms, we revealed that mice lacking the CB1 receptor in serotonergic neurons are more anxious and less sociable than control littermates. Thus, we were able to show that functional CB1 receptor signaling in central serotonergic neurons modulates distinct behaviors in mice.

No MeSH data available.


Related in: MedlinePlus