Developmental changes in MOR levels and function in striosomes of the medial and caudal striatal regions
Striatal regions were determined according to Paxinos and Watson (1986): medial, plates 22–24; caudal, plates 29–31. Postnatal age was measured from time of birth (within 12 h); adult animals were determined by weight (250 ± 25 g). Data are presented as the means ± S.E.M. of four striosomes from each of four tissue sections averaged from each of three to four rat brains. Basal [35S]GTPγS binding and DAMGO-stimulated [35S]GTPγS binding (stimulated minus basal) were measured from the same striosomes using adjacent tissue sections. The coupling ratio is the ratio of DAMGO-stimulated [35S]GTPγS binding to [3H]DAMGO binding of individual striosomes multiplied by 100.
Striatal Region | Postnatal Age | [3H]DAMGO Binding | Basal [35S]GTPγS Binding | Agonist-Stimulated [35S]GTPγS Binding | Coupling Ratio | -Fold Increase in Coupling Ratio (Compared with Day 5) |
|---|---|---|---|---|---|---|
| fmol/mg tissue | ||||||
| Medial | Day 5 | 61.6 ± 3.1 | 0.13 ± 0.01 | 0.19 ± 0.03 | 0.32 ± 0.07 | 1.0 |
| Day10 | 76.7 ± 4.4 | 0.24 ± 0.02 | 0.31 ± 0.12 | 0.39 ± 0.12 | 1.2 | |
| Day15 | 74.4 ± 18 | 0.47 ± 0.1 | 0.70 ± 0.31 | 0.80 ± 0.13 | 2.5 | |
| Day21 | 68.0 ± 2.7 | 0.59 ± 0.03 | 1.22 ± 0.27 | 1.81 ± 0.33 | 5.7 | |
| Day30 | 77.0 ± 7.4 | 0.61 ± 0.02 | 1.47 ± 0.06 | 1.97 ± 0.12 | 6.2 | |
| Ad | 59.1 ± 9.6 | 0.62 ± 0.04 | 1.61 ± 0.25 | 2.34 ± 0.28 | 7.4 | |
| Caudal | Day 5 | 55.5 ± 4.4 | 0.16 ± 0.01 | 0.22 ± 0.05 | 0.38 ± 0.05 | 1.0 |
| Day10 | 60.5 ± 7.8 | 0.27 ± 0.02 | 0.31 ± 0.13 | 0.44 ± 0.15 | 1.1 | |
| Day15 | 68.3 ± 12 | 0.48 ± 0.05 | 0.65 ± 0.08 | 1.01 ± 0.13 | 2.6 | |
| Day21 | 41.3 ± 1.1 | 0.50 ± 0.01 | 0.89 ± 0.22 | 2.20 ± 0.46 | 5.7 | |
| Day30 | 49.2 ± 1.3 | 0.66 ± 0.08 | 1.23 ± 0.19 | 2.59 ± 0.43 | 6.8 | |
|
| Ad | 40.8 ± 6.1 | 0.74 ± 0.2 | 0.77 ± 0.25 | 2.01 ± 0.76 | 5.3 |