LEUCOKININ AND DIURETIC HORMONE IMMUNOREACTIVITY OF NEURONS IN THE TOBACCO HORNWORM, MANDUCA-SEXTA, AND COLOCALIZATION OF THIS IMMUNOREACTIVITY IN LATERAL NEUROSECRETORY-CELLS OF ABDOMINAL GANGLIA

Because leucokinins stimulate diuresis in some insects, we wished to i dentify the neurosecretory cells in Manduca sexta that might be a sour ce of leucokinin-like neurohormones. Immunostaining was done at variou s stages of development, using an antiserum to leucokinin IV. Bilatera l pairs of neurosecretory cells in abdominal ganglia 3-7 of larvae and adults are immunoreactive; these cells project via the ipsilateral ve ntral nerves to the neurohemal transverse nerves. The immunoreactivity and size of these lateral cells greatly increases in the pharate adul t, and this change appears to be related to a period of intensive diur esis occurring a few days before adult eclosion. Relationships of thes e neurons to cells that are immunoreactive to a M. sexta diuretic horm one were also investigated. Diuretic hormone and leucokinin immunoreac tivity are co-localized in the lateral neurosecretory cells and their neurohemal projections. A median pair of leucokinin-immunoreactive, an d a lateral pair of diuretic hormone-immunoreactive neurons in the lar val terminal abdominal ganglion project to neurohemal release sites wi thin the cryptonephridium. The immunoreactivity of these cells is lost as the cryptonephridium is eliminated during metamorphosis. This loss appears to be related to the change from the larval to adult pattern of diuresis.