Variation in hippocampal dynorphin b-immunoreactive mossy fiber terminal fields of apomorphine-(un)susceptible rats

The size of distinct hippocampal sub-fields were measured in the apomorphin e-susceptible and apomorphine-unsusceptible rat lines. Mossy fiber terminal fields were delineated using dynorphin B immunoreactivity and area measure ments were taken from (1) the supra-pyramidal mossy fiber terminal field; ( 2) the intra- and infra-pyramidal mossy fiber terminal field; (3) the hilus of the fascia dentata (4) the non dynorphin B immunoreactive area of the r egio inferior and fascia dentata and (5) the total area of regio inferior a nd fascia dentata. The data indicate that statistically significant differe nces in the morphometry of the hippocampal subfields of the apomorphine sus ceptible and unsusceptible rats are confined to the intra- and infra termin al field: the relative size of the left and right intra- and infra terminal field of apomorphine unsusceptible rats are significantly larger than thos e of the apomorphine susceptible rats. These data explain at least in part the differential response of these rats to novelty. (C) 1999 Elsevier Scien ce B.V. All rights reserved.