Info

13S ± 19

Each rat generates two CS, one per each chamber. Maximal response over pretreatment value at interval #3. cp < 0.05 at least.

Each rat generates two CS, one per each chamber. Maximal response over pretreatment value at interval #3. cp < 0.05 at least.

Fig. 3. Rats were ovx and 15-20 d post-ovx received oil and sacrificed on d 3 at 9.00 h. CS fragments were superfused in vitro and at interval 4 stimulated with 10 nM E-6-BSA. To test for viability of the tissue a depolarizing dose of K+ (30 mM) was applied at interval 8. Note a robust response to K+ and a nonsignificant response to E-6-BSA, n = 4 chambers, two rats. Note a different y scale between Figs. 2 and 3.

Fig. 3. Rats were ovx and 15-20 d post-ovx received oil and sacrificed on d 3 at 9.00 h. CS fragments were superfused in vitro and at interval 4 stimulated with 10 nM E-6-BSA. To test for viability of the tissue a depolarizing dose of K+ (30 mM) was applied at interval 8. Note a robust response to K+ and a nonsignificant response to E-6-BSA, n = 4 chambers, two rats. Note a different y scale between Figs. 2 and 3.

1 nM. This membrane-mediated event of E-6-BSA is gender-specific, because similar CS preparations from intact male rats did not respond to a broad range of doses of the conjugate (Fig. 5). A further indication that the hormonal status of the animal appears to be crucial for the expression of this response is the serendipitous finding that CS fragments derived from three rats in constant estrus (with vaginal smear in constant estrus for greater than 12 d) were highly responsive to the infusion of the conjugate, because both

Fig. 4. The effect of ovx and Eb treatment on dopamine release from CS fragments by E-6-BSA. A 2-d treatment with Eb (0.5 ^g s.c. on d 1, followed by 1 ^g on d 2) led on d 3 to a partial recovery of the response to 10 nM E-6-BSA. Symbols indicate significant differences within (*) and between conditions. (#, +)

Fig. 4. The effect of ovx and Eb treatment on dopamine release from CS fragments by E-6-BSA. A 2-d treatment with Eb (0.5 ^g s.c. on d 1, followed by 1 ^g on d 2) led on d 3 to a partial recovery of the response to 10 nM E-6-BSA. Symbols indicate significant differences within (*) and between conditions. (#, +)

a 5 and 25 nM dose were more potent in releasing DA than similar doses in proestrous rats (Table 1).

Hence, it seems that E acts on the extracellular phase of the membranes of the CS neurons to activate a "receptor" that is functionally coupled to DA release only under a certain, critical endogenous hormonal milieu, such as the one present in proestrus, in ovx rats treated with E, or in rats in constant estrus.

0 0

Post a comment