Carp (Cyprinus carpio) liver maintained normal glycogen content and enzyme complement for several days in organ culture. Epinephrine-stimulated glycogenolysis, phosphorylase activation, and cyclic AMP (cAMP) accumulation in a concentration-dependent manner with EC50s of 100, 100, and 500 nM, respectively. These actions were blocked by the beta-adrenergic antagonist, propranolol, but not by the alpha-adrenergic antagonist phentolamine. Glycogenolysis and tissue cAMP were uninfluenced by 10(-6) M arginine vasotocin, arginine vasopressin, lysine vasotocin, lysine vasopressin, mesotocin, or oxytocin, but were slightly increased by 10(-5) M isotocin and slightly decreased by 10(-6) M angiotensin II. [125I]-iodocyanopindolol (ICP), a beta-adrenergic ligand, bound to isolated carp liver membranes with a KD of 83 pM. Maximum binding of 45 fmol/mg protein was at 600 pM. Propranolol, isoprenaline, epinephrine, phenylephrine, norepinephrine, and phenoxybenzamine displaced ICP with KDs of 100 nM, 2, 20, 20, 60, and 200 microM, respectively. The alpha-adrenergic antagonists, yohimbine and prazosin, showed no specific binding. These data provide evidence that catecholamines act via beta-adrenergic receptors in carp liver and that alpha-adrenergic receptors are not present. Vasoactive peptides play no significant role in regulation of carp liver glycogenolysis.

The adrenal of the male tammar wallaby first appears at day 21 of embryogenesis as a nodule of tissue lying close to the anterior pole of the kidney. The nodule consists of adrenocortical tissue in that its cells contain an active 3 beta ol-steroid dehydrogenase from about day 22 of embryogenesis. From day 22 of embryogenesis until at least day 20 of pouch life a sympathetic nerve plexus is adpressed to the medial side of the adrenal. Cells migrate from the plexus through pores in the capsule of the gland and intermingle with the cortical cells. By day 7 of pouch life some of the invading cells display a chromaffin reaction and by day 60 have formed a distinct medulla. The cortex shows the beginnings of zonation by day 60 of pouch life but the three adult zones are not seen until day 200.

Adrenal glands from normal male and female brush-tailed possums (Trichosurus vulpecula) were weighed and sectioned to investigate reported changes in the relative size of the hypertrophied region of the cortex during the reproductive cycle. Total adrenal gland weight in normal females averaged 120 mg/kg body weight and the hypertrophied region occupied 40% of the gland volume. No significant variation was found in these figures between glands from pregnant, lactating and cyclic possums . In addition, no cyclic pattern of cellular changes was found in the hypertrophied region. These results differ from views expressed in the current literature which are based on the original description of the hypertrophied zone.

A heterologous double-antibody radioimmunoassay has been validated for prolactin in plasma and pituitary preparations of T. vulpecula. Serial dilutions of crude pituitary homogenates and plasmas from several marsupials and purified prolactin from the tammar, Macropus eugenii, showed parallel dose response curves. In both male and female possums plasma prolactin concentrations increased in response to a single intravenous injection of thyrotrophin releasing hormone. Plasma prolactin concentrations were measured in six lactating females (June-November) and in four non-lactating females (July-October). In the following year prolactin levels were also measured in 11 possums with young less than 50 days old and in 24 possums with young aged between 100 and 145 days. In early lactation prolactin concentrations were low (less than 8 ng/ml) but increased to high levels (greater than 30 ng/ml) by 120 days and remained high until about 160 days of lactation. Thereafter concentrations declined although the young continued to take milk from the mother for a further 30-50 days. The changes in plasma prolactin concentrations throughout lactation are very similar to those described for the tammar, and this unusual pattern appears to be common to marsupials. Non-lactating possums showed no consistent changes in plasma prolactin concentrations between July and October.

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