Synthesis and Secretion of Intestinal Digestive Enzymes in the Adult Female Orienta Cockroach, Blatta orientalis,1 with Reference to the Neviroendocrine System2

Abstract

Removal of the median neurosecretory cells (m.n.c.) in adult female Blatta orientalis L. (Orthoptera: Blattidae) did not significantly affect the total activities of midgut amylases, lipases, and esterases, measured 4 weeks after median neurosecretory cells cautery. The total activity of midgut proteases was likewise unaffected by 2 weeks m.n.c. cautery and it was concluded that a general neuroendocrine control over the synthesis of digestive enzymes does not exist in this insect; secretagogues and/or nervous stimulation probably control the synthesis of digestive enzymes by the midgut epithelial cells. Tissue and lumen midgut protease fractions were separately assayed after 2 weeks m.n.c. cautery, but the results were inconclusive. However, a possible neuroendocrine control of enzyme secretion by the midgut epithelial cells cannot be entirely precluded. Detection of amylases in whole midgut homogenates does not necessarily imply their production by the midgut epithelial cells, since they may have originated from another site (e.g., the salivary glands). The effects of m.n.c. cautery on the fecundity of the female cockroach suggest that the m.n.c. are involved in the control of protein metabolism. The reproductive processes of both 2-week and 4-week m.n.c.-cauterized insects were severely affected and this result was manifested by a profound decrease in growth of the terminal oocytes, an increase in the percentage of terminal oocytes affected by resorption bodies, and suppression of ootheca production. It is to be concluded that the basis of the neuroendocrine relationship, which exists between the cockroach and its intestinal nematode, Hammerschmidtiella diesingi Hammerschmidt, does not involve the synthesis of the host's digestive enzymes by the midgut epithelial cells.