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To clarify the different actions of steroid hormones on calling and locomotor activity, minute pellets of steroid hormones were stereotaxically implanted into the third ventricle of castrated Japanese quail. Testosterone (T) pellets were effective in inducing calling to about 60% of that observed in castrated quail given subcutaneous implants of T. However, implants of 5α-dihydrotestosterone (5α-DHT) were completely ineffective and effectiveness of estradiol-17β (E 2 ) was very slight, if any. On the other hand, E 2 and T pellets enhanced locomotor activity; E 2 was more potent than T, whereas 5α-DHT was again ineffective. Cholesterol pellets had no effects on either behavior. Daily rhythms of calling and locomotor activity were also found in birds given ventricular T implants. These results indicate that T but not E 2 is required for induction of calling and that aromatization occurs in the brain to exert enhanced locomotor activity. The results also indicate that changes in circulating T do not influence daily rhythms of calling and locomotor activity.

Previous investigations have shown that malemale interactions over territory boundaries result in an increase in plasma levels of testosterone (T). In order to determine the time course of this increase following an agonistic challenge, male song sparrows, Zonotrichia (= Melospiza) melodia, were exposed to simulated territorial intrusions. Responding males were captured at intervals after onset of the intrusion for up to 60 min. Plasma levels of T were elevated by 10 min after onset of the challenge, and remained high in birds sampled 10–60 min after onset of the intrusion. In addition, plasma levels of luteinizing hormone (LH) increased and were significantly elevated after 10 min of stimulation. The results suggest that at least the prolonged elevation of T secretion precipitated by a male-male interaction was mediated via an increase in LH release. However, the initial surge of T levels in plasma may be LH independent. p Investigations of captive birds confirmed that circulating LH and T levels increased when male song sparrows were challenged by a conspecific male. Challenges involving a male house sparrow, Passer domesticus, had no effect suggesting that responses to male intrusions were species characteristic and not a result of general arousal. Further, auditory stimuli (vocalizations) alone, and visual stimuli (a devocalized male) alone were less effective in stimulating an increase in secretion of T than a combination of auditory and visual stimuli.

Repetitive blood sampling from Japanese quail showed that plasma LH concentration rose during the first dark period after the birds were transferred from 8L:16D to 16L:8D. In the second light period of long days, LH concentration decreased slightly (not significant) and maintained this lower level until the second dark period of long days. During the second dark period LH again increased. This suggests that at the first stage of LH release by long photoperiod, photoinduction can occur at least during 8 to 16 hr after lights are turned on. To test the hypothesis that LH secretion induced by long days is dependent on the photoinducible phase, 0.5-hr light pulses (0.5L) were given to quail kept under 8L:16D during the dark periods. Activity was also recorded for each bird. After 10 days of treatment, testicular growth was induced when 0.5L pulses were given at 13 or 19 hr after dawn. Testicular growth induced by 0.5L pulses given at 19 hr after dawn was less than that in birds given light 13 hr after dawn and had greater individual variation compared with other groups. The activity records of these birds revealed that some remained entrained to the primary light pulse (8 hr) while others phase shifted to the short pulse (0.5 hr). The latter were, in effect, then exposed to a 13-hr photoperiod while the former were exposed to 8L:11D: 0.5L:4.5D. LH increase by 0.5L given during the dark period was detected after 2 days of treatment when the pulses were delivered at 15 hr after dawn. These results suggest that LH release is induced when light impinges on the circadian photosensitive phase which is set by external lighting schedules.

A so-called “night-interruption” experiment with a 15-min light pulse showed that a sensitive phase for the photoperiodic LH secretion in male Japanese quail extended over a period of 2 hr from 12.5 to 14.5 hr after dawn. Exposure of a 1-hr light pulse at this photosensitive phase to male quail kept under 8L:16D induced the increase of plasma LH concentrations just the same as quail transferred to 16L:8D. In the first few days of photostimulation either by night interruption or by long days, LH concentrations increased at several hours after the photosensitive phase and decreased to the basal levels before day-break. The amplitude and duration of this LH surge was somewhat like a preovulatory LH surge in females. However barbiturate anesthesia (pentobarbital and phenobarbital) administered on, before, or after the photosensitive phase did not block the LH increase by photostimulation. On the other hand, an injection of phenobarbital 14 hr before the expected ovulation blocked a preovulatory LH surge, even though the same drug failed to block photoinduced LH increase in females. These results indicate that the neuroendocrine mechanism involved in photostimulated LH release is different from that for an LH surge during an ovulatory cycle.

Following the bilateral implantation of puromycin into the paraventricular nuclei of rats, the neurosecretory cells became atrophic and the amount of aldehyde-fuchsin (AF) positive material in the neural lobe decreased. In these rats, urine excretion and water intake increased remarkably. The supraoptic nuclei of the rats were not affected by this treatment. After the unilateral implantation of puromycin in the paraventricular nucleus, the neurosecretory cells of the implanted side became atrophic, while those of the unimplanted side hypertrophied. The neural lobe contained similar amounts of AF-positive material to those of the control rats with unilateral cholesterol implants. In the rats implanted bilaterally with puromycin immediately above the supraoptic nucleus, the neurosecretory cells of this nucleus contained little or no AF-positive material, and urine excretion and water intake increased greatly. The cells of the paraventricular nucleus remained unchanged in these rats.

An experimental method for measurement of the low-temperature heat capacity at hydrostatic pressures and external magnetic fields was developed. Also, a suitable pressure-transmitting medium (Apieson-J oil) was found which had good thermal properties for the present method to measure the thermal and magnetic properties of a single crystal of CuCl2·2H2O (T N=4.33 K) at hydrostatic pressures of up to 6 kbar.