>1. Your behavioral findings on the effects of prenatal stress on later induction latencies is fascinating....Any idea about the type of maternal behavior shown by the stressed moms? I ask this because we have found that if moms show reduced licking of their litter, the litter grow up showing altered maternal responsiveness to their offspring. Have you done any cross-fostering?
>2. Your findings that in the maternally-inexperienced animal one only sees c-fos expression associated with maternal behavior in the aob under conditions where maternal behavior is actually being expressed is certainly consistent with previous work by Numan as well as by our group for c-fos expression within the mpoa-Do you think the same results would be found if animals were exposed to a novel odor, instead of pups?
>3. If one looks at the density and pattern of c-fos expression in the 5 prenatally stressed animals that in fact did show maternal behavior during inductions and compared them with the nonstressed maternal animals, do you find any differences?
Thaks very much for your active participation and for your interesting insights and questions.
In response to your three quotations we'll follow the same order:
1.- In a previous study (SACNAS. National Conference. Houston, Texas, 9-12-1997) we have found that the postpartum MB in mothers which have been stressed during pregnancy (day 14 to 21) vs. non stressed mothers has been affected in two parameters:
a) retrieving rate; that is, the total time spent in retrieving the whole litter, divided by the number of litter pups. Stressed mothers during gestation spent more time per pup than non-stressed mothers.
b) the stressed mothers showed less licking than non-stressed.
We have not made a cross-fostering design yet, but we will. As a matter of fact, we included these groups in our former experimental design in order to know whether the behavioral and/or neurophysiological effects could be caused just "by the hormone environmental state during critical periods of neural development and/or by the altered maternal interaction". We have also measured body weight, as well as other developmental milestones (mammarian gland irruption, vaginal opening, testes descent, eyes opening, hair appearance...) and we have not found any significant difference between pups from stressed and non-stressed mothers.
2.- Again, Alison you are pointing out a question which is not yet answered in our work. We need another experiment including groups of prenatlly stressed and control females and prenatally stressed and control naive males, and expose them to novel stimulus different from pups, such as soft and pup-shape bar of candy or chocolate, etc.
Hypothetically, we should expect, based in our inhibitory hypothesis of VNS structures, that c-fos expression will be the same in all groups.
Othewise, we need to see these results taking into account the effects of glucocorticoids and other steroids on the experession of c-fos (Dong Liu et. al, Science 277, pp 1659-62, 1997).
3.- The prenatally stressed animals don't showed any behavior directed to the pups. Just one of the 16 animals that were tested for induction of MB showed MB partially and also showed significantly higher c-fos expression in both structures we have looked, AOB and MPOA, even though we have not included MPOA in this work. The five animals which data for c-fos expression appear in this work did not performed MB throughout the 12 days of the MB induction test.