HAEMOLYMPH AND TISSUE TITRES OF ACHETAKININS IN THE HOUSE CRICKET ACHETA DOMESTICUS: EFFECT OF STARVATION AND DEHYDRATION
Achetakinin-like immunoreactive material in tissues and haemolymph of adult male crickets was quantified by radioimmunoassay. Achetakinin-like material was found in the brain, suboesophageal ganglia and the thoracic and abdominal ganglia, but the largest amount was within the retrocerebral complex. A Ca2+-dependent release of achetakinin-like immunoreactive material was demonstrated from retrocerebral complexes incubated in vitro in saline containing a high concentration of K+. The concentration of achetakinin-like material in haemolymph from fed crickets was estimated to be 2.8 nmol l-1 and increased more than 10-fold in insects starved for 48 h without access to water. The presence of achetakinin-like material in haemolymph suggests that these peptides are released in vivo and function as circulating neurohormones.