XXXX D1 receptor blockage potentiates @entity140 -stimulated luteinising hormone release in the @entity2083 .

@entity10095 @entity2227 @entity72403 @entity935 @entity3216 @entity140 @entity2083
Previous microarray analyses of the @entity2083 hypothalamus led us to hypothesise that @entity935 could potentially inhibit the excitatory effects of @entity2227 on luteinising hormone (LH). Post-spawning female @entity2083 were pre-treated (-4.5 h) with either saline (C; control), @entity10095 (S; D(1) -receptor antagonist) or @entity3216 (L; D(2) -receptor antagonist), followed by an i.p. injection, at -0.5 h, of saline or the @entity2227 agonist @entity140 (A, SA or LA). Blood, hypothalamus and telencephalon tissues were collected. Serum LH was not affected in the S, L, A, or LA groups relative to control as determined by radioimmunoassay. The SA group, however, showed a 289% (P<0.0005) increase in serum LH compared to either treatment alone or control. Real-time reverse transcriptase-polymerase chain reaction identified the mRNAs for ionotropic (Gria2a, Gria4) @entity2227 receptor subunits, activin ba, @entity72403 , and cGnRH-II as being significantly affected by some of the treatments. The same experiment conducted with sexually-regressed female fish showed a very different LH profile, indicating that this mechanism is seasonally-dependent. We also show that i.p. injection of 1  g/g @entity72403 was able to increase LH levels by 167% in sexually regressed female fish relative to controls. Taken together, these results demonstrate that blockage of the D(1) receptor primes post-spawning @entity2083 for @entity140 -stimulated LH release, and provides further insights into the central regulation of reproduction.
