Octopamine, the hypertrehalosemic peptides HT-I and HT-II and the calcium ionophore A23187 elevate intracellular calcium levels in cultured haemocytes of Malaeosoma disstria (Lepidoptera: Lasiocampidae). The octopamine-mediated response is dose-dependent and the magnitude of the response is influenced by the concentration of calcium in the incubation medium. Mianserin, an inhibitor of octopamine-mediated elevation of cyclic AMP production, blocks the octopamine-mediated increase in intracellular calcium but has no effect on the HT-I-and HT-II-mediated responses. The results indicate that some effects of octopamine are mediated through agonist-dependent calcium gating whereas others are expressed through receptors coupled to adenylate cyclase. The study also confirms previous suggestions that HT-I and HT-II elevate intracellular calcium concentrations.

The mean plasma level of beta-endorphin in the newt, Notophthalmus viridescens, as measured by radioimmunoassay, is significantly higher than the circulating levels of beta-endorphin in the anuran, Rana pipiens, and in mammals (humans and mice). The newt beta-endorphin level is found to be 6-fold greater than mammalian levels and three times greater than the levels observed in Rana pipiens. The high levels are maintained in the newt throughout limb regeneration.

This work provides data demonstrating a stimulatory effect of insulin on macromolecular events occurring in cultured regeneration blastemata and demonstrates a synergistic interdependence between nerves and insulin in newt limb regeneration. The current experiments provide evidence for the following: (1) Insulin is paramount for expression of the mitogenic effect of nerves on cultures blastemata. (2) Insulin stimulates the incorporation of (3H)uridine into the acid-insoluble fraction of blastemal homogenates, but it does not alter the turnover rate of incorporated labeled uridine. (3) Insulin also stimulates the incorporation of 35SO4 and (3H)leucine into both chondroitinase-sensitive and chondroitinase-resistant blastemal proteoglycans. (4) Insulin increases the uptake of radiolabeled precursors by the blastemata, namely, (3H)leucine, (3H)uridine, 35SO4, (3H)alpha-aminoisobutyrate, and (3H)2-deoxy-D-glucose. The importance of insulin in the regulation of newt limb regeneration is discussed.

The Luteinizing Hormone Releasing Hormone (LHRH) activity of (D-Ala6, Des-Gly10) LHRH ethylamide was compared with that of LHRH in oöphorectomized bonnet monkeys by determining serum LH and FSH concentrations at various time intervals after a sc injection of 100 mug of LHRH and either 100 mug or 1 mg of the analogue. Following administration of synthetic LHRH, a significant rise in both serum LH and FSH was observed. In contrast, no discernible change in serum gonadotropin concentrations was noted following injection of the analogue (D-Ala6, Des-Gly10) LHRH ethylamide, previously reported to have greatly increased potency in rats and mice.