Influence of maternal corticosterone treatment on incubation length of eggs laid by Japanese quail hens selected for divergent adrenocortical stress responsiveness.

1. Previous studies have shown that more yolk corticosterone is found in the eggs of random bred Japanese quail hens implanted with corticosterone during egg formation; both unstressed and stressed quail hens selected for exaggerated (high stress) rather than reduced (low stress) plasma corticosterone response to brief restraint deposit more corticosterone into their egg yolks. The length of egg incubation is also known to be shorter in eggs laid by high than low stress hens. 2. Here we investigated the interactive effects of quail stress line (low vs. high stress) with maternal corticosterone treatment (empty implant controls vs. corticosterone-implants) during egg formation on length of egg incubation. 3. Mean (+/-SEM) length of egg incubation for high stress control eggs (3973 +/- 04 h) was similarly shorter (by about 4.5 h) than that found for low stress control eggs (3928 +/- 02 h). In addition, on average, the incubation length of eggs laid by corticosterone-implanted hens (3929 +/- 05 h) was nearly 3 h shorter than that found for eggs laid by control hens (3958 +/- 02 h) regardless of stress line. 4. Line x hen-implant treatment effects on mean (+/-SEM) length of egg incubation partitioned in rank order as follows: low stress control (3978 +/- 05 h) > low stress corticosterone-implant (3959 +/- 07 h) > high stress control (3938 +/- 03 h) > high stress corticosterone-implant (3912 +/- 04 h). 5. Our original contention that selection for exaggerated adrenocortical responsiveness is associated with a reduction in the length of egg incubation was supported. Because maternal stress-induced elevations of yolk B are known to occur, the present findings of further shortenings of the hatching times of eggs of corticosterone-treated hens of both stress lines are also important to the poultry industry because they warn producers that unless stress in hens during egg formation is minimised, abbreviated egg incubation periods may result beyond the effects that a hen's genetic predisposition to adrenocortical stress responsiveness has on the length of egg incubation.

Fronto-striato-thalamic perfusion and clozapine response in treatment-refractory schizophrenic patients. A 99mTc-HMPAO study.

Several studies with functional and structural brain-imaging techniques support the hypothesis that responders and non-responders to clozapine could show a different pattern of cerebral dysfunction. Thirty-nine neuroleptic-refractory schizophrenic patients were studied with 99Tc-labelled hexamethyl-propylene-aminoxime (HMPAO) and SPECT, while on classical neuroleptics and after 6 months of treatment with clozapine. The perfusion differences between responders and non-responders to clozapine were studied in the regions included within the dorsolateral and orbitofrontal fronto-striato-thalamic circuits, as well as the predictive value of these parameters. These values were compared to those of a normal database, and between both treatments within the two groups. On-neuroleptic perfusion in non-responders was lower in the thalamus, basal ganglia and dorsolateral prefrontal cortex. Thalamus and right prefrontal perfusion regions were selected as response predictors by a discriminant analysis. Thalamic and left basal ganglia activities while on neuroleptics were lower only in non-responders with respect to the normal subjects. Perfusion changes were only observed in the responder group in thalamus and basal ganglia. Study of regional perfusion may contribute to the prediction of clozapine response.