Article Figures & Data
Figures
- Figure 1.
Dopamine varicosity density in the oPFC is protracted across adolescence. A, Timeline of experimental procedures; n = 4 per group. B, A micrograph of a coronal section through the frontal cortex of an adult mouse at low magnification (4×) showing the contour of the oPFC. Scale bar = 500 μm. C, A micrograph of a coronal section of the oPFC of an adult mouse at high magnification (60×) showing TH-immunopositive varicosities. Scale bar = 10 μm. D, The voPFC, loPFC, vaiPFC, and daiPFC respectively, are highlighted in increasingly pale shades of purple. Line drawings were derived from Paxinos and Franklin (2013). E, Stereological quantification of dopamine varicosity density reveals that there are more dopamine varicosities in the adult oPFC than the adolescent. Bars represent mean ± standard error (Extended Data >Fig. 1-1).
- Figure 2.
Axons continue to grow to the oPFC during adolescence. A, The dual-viral injection method used to label NAcc-projecting ventral tegmental area neurons with eYFP. B, Timeline of experimental procedures: mice were injected at the start of adolescence (PND22 ± 1) and six weeks later, at which point adolescent mice have reached adulthood, eYFP-expressing dopamine axons in the oPFC were quantified; n = 5. C–E, Micrographs of a coronal section of the oPFC of an adult mouse at high magnification (60×) show (C) TH-immunopositive varicosities, (D) eYFP-expressing varicosities, and (E) an overlay highlighting co-labeled varicosities. Scale bar = 10 μm. F, The voPFC, loPFC, vaiPFC, and daiPFC, respectively, are highlighted in increasingly pale shades of purple. Line drawings were derived from Paxinos and Franklin (2013). G, Stereological quantification of dopamine varicosity density reveals eYFP-expressing dopamine varicosities are present in the oPFC in adult mice that received dual-viral injections in early adolescence (Extended Data Fig. 2-1). H, To ensure the eYFP-expressing dopamine neurons in the oPFC were the result of axon growth and not collaterals, we injected viruses into early adult mice and quantified eYFP-expressing dopamine axons six weeks later; n = 3. I, eYFP-expressing dopamine varicosities are almost entirely absent from the orbital prefrontal cortices of mice that were injected during adulthood (Extended Data Fig. 2-1). G & I, Bars represent mean ± standard error.
- Figure 3.
Amphetamine in adolescence alters dopamine connectivity in adulthood. A, Timeline of experimental procedures; n = 4 per group. B, The loPFC, vaiPFC, and daiPFC, respectively, are highlighted in increasingly pale shades of red. Line drawings were derived from Paxinos and Franklin (2013). C, Stereological quantification of dopamine varicosity density reveals that adults exposed to amphetamine during adolescence have about a 40% reduction in dopamine varicosity density in the oPFC compared to saline-treated controls. Bars represent mean ± standard error (Extended Data Fig. 3-1).
- Figure 4.
Dopamine connectivity in the piriform cortex is not protracted nor influenced by amphetamine in adolescence. A, The piriform cortex was outlined based on Paxinos and Franklin (2013) and is highlighted in green. B, C, Stereological quantification of dopamine varicosity density reveals that (B) early adolescent mice have a significantly higher density of dopamine varicosities in the piriform cortex compared to adults (Extended Data Fig. 4-1) and (C) that amphetamine exposure during adolescence does not alter the density of dopamine varicosities in the piriform cortex. Bars represent mean ± standard error (Extended Data Fig. 4-2).
Extended Data
Extended Data Legends
Extended Data Figure 1-1. Dopamine (TH-immunopositive) varicosity density estimates for four subregions of the oPFC in adult and early adolescent mice. Varicosity density was estimated by combining the optical fractionator and Cavelieri estimator methods of the software program Stereoinvestigator (see Materials and Methods). These data were used to generate the results presented in Results, Dopamine innervation to the oPFC is protracted across adolescence, and Figure 1.
Extended Data Figure 2-1. Density estimates of dopamine (TH; TH-immunopositive) varicosities that have been infected with a fluorescent protein-expressing virus for four subregions of the oPFC in adult and early adolescent mice. Varicosity density was estimated by combining the optical fractionator and Cavelieri estimator methods of the software program Stereoinvestigator (see Materials and Methods). These data were used to generate the results presented in Results, Delayed dopamine innervation to the oPFC results from ongoing axon growth, and Figure 2.
Extended Data Figure 3-1. Dopamine (TH-immunopositive) varicosity density estimates in four subregions of the oPFC in adult mice treated with either saline or amphetamine in early adolescence. Varicosity density was estimated by combining the optical fractionator and Cavelieri estimator methods of the software program Stereoinvestigator (see Materials and Methods). These data were used to generate the results presented in Results, Amphetamine in adolescence reduces dopamine varicosity density in the adult oPFC, and Figure 3.
Extended Data Figure 4-1. Dopamine (TH-immunopositive) varicosity density estimates for the piriform cortex in adult and early adolescent mice. Varicosity density was estimated by combining the optical fractionator and Cavelieri estimator methods of the software program Stereoinvestigator (see Materials and Methods). These data were used to generate the results presented in Results, Dopamine innervation to the piriform cortex is not protracted nor influenced by amphetamine in adolescence, and Figure 4B.
Extended Data Figure 4-2. Dopamine (TH-immunopositive) varicosity density estimates for the piriform cortex in adult mice treated with either saline or amphetamine in early adolescence. Varicosity density was estimated by combining the optical fractionator and Cavelieri estimator methods of the software program Stereoinvestigator (see Materials and Methods). These data were used to generate the results presented in Results, Dopamine innervation to the piriform cortex is not protracted nor influenced by amphetamine in adolescence, and Figure 4C. Download Tables, DOCX file.
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