Neuronal localization of 5-HT2A receptor immunoreactivity in the rat hippocampal region

Ventral hippocampal parvalbumin interneurons gate the acute anxiolytic action of the serotonergic psychedelic DOI

“…Our opto-tagging experiments confirm that acute DOI administration enhances the firing rate of PV-positive FS neurons in the vHpc CA1/sub region. Furthermore, RNAscope analysis indicates the robust expression of 5-HT 2A receptors on almost all PV-positive neurons in this region, which agrees with prior evidence that 5-HT 2A receptors are expressed by most GABAergic neurons in the vHpc 54 – 56 . However, it is interesting that our electrophysiological experiments suggest that the DOI-evoked increase in firing rate appears to be restricted to a subset of 5-HT 2A receptor expressing PV-positive neurons in the vHpc CA1/sub region.…”

Ventral hippocampal parvalbumin interneurons gate the acute anxiolytic action of the serotonergic psychedelic DOI

“…Our opto-tagging experiments confirm that acute DOI administration enhances the firing rate of PV-positive FS neurons in the vHpc CA1/sub region. Furthermore, RNAscope analysis indicates the robust expression of 5-HT 2A receptors on almost all PV-positive neurons in this region, which agrees with prior evidence that 5-HT 2A receptors are expressed by most GABAergic neurons in the vHpc 54 – 56 . However, it is interesting that our electrophysiological experiments suggest that the DOI-evoked increase in firing rate appears to be restricted to a subset of 5-HT 2A receptor expressing PV-positive neurons in the vHpc CA1/sub region.…”

Ayahuasca enhances the formation of hippocampal-dependent episodic memory without impacting false memory susceptibility in experienced ayahuasca users: An observational study

“…One clue may come from the doses of DMT and β-carbolines. Whereas 170.64 mg of βcarbolines was similar to prior work, 3.36 mg of DMT was 10-20 times lower (Callaway et al, 1999;Dos Santos et al, 2011, 2012Riba et al, 2003). Despite this low dose of DMT, plasma concentrations of DMT and subjective effects (see Ramaekers et al, 2023) were similar to those from studies administering ayahuasca containing higher DMT doses.…”

“…Pre-encoding administration of GABA A sedatives (e.g., alcohol), NMDA dissociatives (e.g., ketamine), and THC impairs recollection, as well as familiarity (Doss et al, 2023b). Like these other drugs and consistent with the expression of 5-HT 2A receptors on inhibitory neurons in the hippocampus and the input to the hippocampus (i.e., entorhinal cortex; Bombardi, 2012;de Filippo et al, 2021;Deng and Lei, 2008;Lüttgen et al, 2004;Shen and Andrade, 1998;Wyskiel and Andrade, 2016), pre-encoding psilocybin and MDMA administration impaired memory on a recollectionbased task (verbal-free recall; Barrett et al, 2018;van Wel et al, 2011) and recollection estimates from the dual process signal detection (DPSD) model (Doss et al, 2023b). However, DPSD familiarity estimates tended to be enhanced by pre-encoding psilocybin and MDMA administration, perhaps owing to 5-HT 2A expression on excitatory cortical neurons (Aghajanian and Marek, 1997;Jakab and Goldman-Rakic, 1998;Martin and Nichols, 2016).…”

Functional anatomy of 5-HT2A receptors in the amygdala and hippocampal complex: relevance to memory functions

“…In addition, high levels of 5-HT 2A R mRNA levels are located in the rat entorhinal cortex, particularly in layers v and vI (Pompeiano et al 1994). These data coincide with immunohistochemical studies showing that a variety of morphological cell types is distributed in the rat entorhinal cortex and elsewhere in the rat parahippocampal region (Cornea-Hébert et al 1999;Bombardi 2012).…”

Ventral hippocampal parvalbumin interneurons gate the acute anxiolytic action of the serotonergic psychedelic DOI

“…Our opto-tagging experiments confirm that acute DOI administration enhances the firing rate of PV-positive FS neurons in the vHpc CA1/sub region. Furthermore, RNAscope analysis indicates the robust expression of 5-HT 2A receptors on almost all PV-positive neurons in this region, which agrees with prior evidence that 5-HT 2A receptors are expressed by most GABAergic neurons in the vHpc 54 – 56 . However, it is interesting that our electrophysiological experiments suggest that the DOI-evoked increase in firing rate appears to be restricted to a subset of 5-HT 2A receptor expressing PV-positive neurons in the vHpc CA1/sub region.…”

Ayahuasca enhances the formation of hippocampal-dependent episodic memory without impacting false memory susceptibility in experienced ayahuasca users: An observational study

“…One clue may come from the doses of DMT and β-carbolines. Whereas 170.64 mg of βcarbolines was similar to prior work, 3.36 mg of DMT was 10-20 times lower (Callaway et al, 1999;Dos Santos et al, 2011, 2012Riba et al, 2003). Despite this low dose of DMT, plasma concentrations of DMT and subjective effects (see Ramaekers et al, 2023) were similar to those from studies administering ayahuasca containing higher DMT doses.…”

“…Pre-encoding administration of GABA A sedatives (e.g., alcohol), NMDA dissociatives (e.g., ketamine), and THC impairs recollection, as well as familiarity (Doss et al, 2023b). Like these other drugs and consistent with the expression of 5-HT 2A receptors on inhibitory neurons in the hippocampus and the input to the hippocampus (i.e., entorhinal cortex; Bombardi, 2012;de Filippo et al, 2021;Deng and Lei, 2008;Lüttgen et al, 2004;Shen and Andrade, 1998;Wyskiel and Andrade, 2016), pre-encoding psilocybin and MDMA administration impaired memory on a recollectionbased task (verbal-free recall; Barrett et al, 2018;van Wel et al, 2011) and recollection estimates from the dual process signal detection (DPSD) model (Doss et al, 2023b). However, DPSD familiarity estimates tended to be enhanced by pre-encoding psilocybin and MDMA administration, perhaps owing to 5-HT 2A expression on excitatory cortical neurons (Aghajanian and Marek, 1997;Jakab and Goldman-Rakic, 1998;Martin and Nichols, 2016).…”

Functional anatomy of 5-HT2A receptors in the amygdala and hippocampal complex: relevance to memory functions

“…In addition, high levels of 5-HT 2A R mRNA levels are located in the rat entorhinal cortex, particularly in layers v and vI (Pompeiano et al 1994). These data coincide with immunohistochemical studies showing that a variety of morphological cell types is distributed in the rat entorhinal cortex and elsewhere in the rat parahippocampal region (Cornea-Hébert et al 1999;Bombardi 2012).…”

Ventral hippocampal parvalbumin interneurons gate the acute anxiolytic action of the serotonergic psychedelic DOI

“…Our opto-tagging experiments confirm that acute DOI administration enhances the firing rate of PV-positive FS neurons in the vHpc CA1/sub region. Furthermore, RNAscope analysis indicates the robust expression of 5-HT 2A receptors on almost all PV-positive neurons in this region, which agrees with prior evidence that 5-HT 2A receptors are expressed by most GABAergic neurons in the vHpc 54 – 56 . However, it is interesting that our electrophysiological experiments suggest that the DOI-evoked increase in firing rate appears to be restricted to a subset of 5-HT 2A receptor expressing PV-positive neurons in the vHpc CA1/sub region.…”

Ayahuasca enhances the formation of hippocampal-dependent episodic memory without impacting false memory susceptibility in experienced ayahuasca users: An observational study

“…One clue may come from the doses of DMT and β-carbolines. Whereas 170.64 mg of βcarbolines was similar to prior work, 3.36 mg of DMT was 10-20 times lower (Callaway et al, 1999;Dos Santos et al, 2011, 2012Riba et al, 2003). Despite this low dose of DMT, plasma concentrations of DMT and subjective effects (see Ramaekers et al, 2023) were similar to those from studies administering ayahuasca containing higher DMT doses.…”

“…Pre-encoding administration of GABA A sedatives (e.g., alcohol), NMDA dissociatives (e.g., ketamine), and THC impairs recollection, as well as familiarity (Doss et al, 2023b). Like these other drugs and consistent with the expression of 5-HT 2A receptors on inhibitory neurons in the hippocampus and the input to the hippocampus (i.e., entorhinal cortex; Bombardi, 2012;de Filippo et al, 2021;Deng and Lei, 2008;Lüttgen et al, 2004;Shen and Andrade, 1998;Wyskiel and Andrade, 2016), pre-encoding psilocybin and MDMA administration impaired memory on a recollectionbased task (verbal-free recall; Barrett et al, 2018;van Wel et al, 2011) and recollection estimates from the dual process signal detection (DPSD) model (Doss et al, 2023b). However, DPSD familiarity estimates tended to be enhanced by pre-encoding psilocybin and MDMA administration, perhaps owing to 5-HT 2A expression on excitatory cortical neurons (Aghajanian and Marek, 1997;Jakab and Goldman-Rakic, 1998;Martin and Nichols, 2016).…”

Functional anatomy of 5-HT2A receptors in the amygdala and hippocampal complex: relevance to memory functions

“…In addition, high levels of 5-HT 2A R mRNA levels are located in the rat entorhinal cortex, particularly in layers v and vI (Pompeiano et al 1994). These data coincide with immunohistochemical studies showing that a variety of morphological cell types is distributed in the rat entorhinal cortex and elsewhere in the rat parahippocampal region (Cornea-Hébert et al 1999;Bombardi 2012).…”