Hypothalamic and hormonal control of the photoperiodically induced vernal functions in the White-crowned Sparrow,Zonotrichia leucophrys gambelii

To assess the role of the hypothalamo-hypophysial complex in the control of photoperiodically induced vernal premigratory responses in the White-crowned Sparrow, the effects of hypothalamic lesions and systemic administration of several hormones on these responses were investigated. Lesions that destroyed the posterior median eminence (PME) or the entire median eminence (ME) inhibited photoperiodically induced testicular growth, premigratory fattening and Zugunruhe. Lesions in the basal infundibular nucleus (IN) that resulted in complete inhibition of testicular growth abolished Zugunruhe, but allowed varying degrees of fattening. The systemic administration of prolactin, testosterone propionate (TP) or the combination thereof in the PME-lesioned birds induced fattening similar to that observed in photostimulated controls but did not induce Zugunruhe. It is concluded that testosterone and prolactin are the most important hormones involved in the control of vernal premigratory fattening. The role of these hormones in the induction of vernal Zugunruhe is not positively proven.     

Fluorescence microscopy of neurons containing primary catecholamines in the ventral hypothalamus of the white-crowned sparrow,Zonotrichia leucophrys gambelii

Summary The ventral hypothalamus of White-crowned Sparrows, Zonotrichia leucophrys gambelii, was examined for primary catecholamines with the fluorescence technique of Falck-Hillarp and Owman. Photorefractory and photosensitive birds, photoperiodically stimulated and non-stimulated, were used.Four groups of catecholaminergic fibers were demonstrated: (1) afferent fibers of extra-hypothalamic origin to the infundibular nucleus where there are extensive synaptic contacts with non-fluorescent perikarya; (2) fibers apparently extending ventrally from an area with fluorescent perikarya in the vicinity of the paraventricular organ to the infundibular nucleus via the stratum cellulare internum and lateral pathways; (3) afferent fibers to the subependymal layer of the median eminence; and (4) afferent fibers to the zona externa of the median eminence. Fluorescent fibers that pass transversely through the median eminence may be derived from any of the last three categories. It appears that the fibers of the zona externa (4) are not derived to any appreciable extent from those of the subependymal layer (3). Because fluorescent perikarya could not be demonstrated in the infundibular nucleus no conclusion can be reached with respect to this nucleus as an origin for fibers (3) and (4).Diurnal cycles in the number of fluorescent terminals observable and in the intensity of the fluorescence in the palisade layer in photosensitive birds subjected to different photoperiodic regimes, in castrates, and in photorefractory birds are described tentatively on the basis of subjective assessments. Some possible implications of the differences are discussed.This communication is based extensively on a thesis, Primary catecholamine fibers in the ventral hypothalamus of the White-crowned Sparrow, Zonotrichia leucophrys gambelii, submitted in partial fulfillment of the requirements for the degree of Master of Science, University of Washington, August 1968, by the senior author. The research on which it is based was supported extensively by Grant No. NB 06187 from the National Institutes of Health to Professor Donald S. Farner. We are grateful to Ciba Pharmaceutical Products, Inc. for a supply of Serpasil.     

The ultrastructure of the cells of Leydig in the white-crowned sparrow (Zonotrichia leucophrys gambelii) in relation to plasma levels of luteinizing hormone and testosterone

In male White-crowned Sparrows subjected to 20 h daily photoperiods there is an approximately 3-fold increase in the plasma concentration of luteinizing hormone (LH) on the first long day after which a quasi-stable level is maintained for at least 42 days. This increase is followed by an increase in numbers of cells of Leydig and an enhancement of their steroidogenic features, a decrease in transitional interstitial cells, and an increase in plasma level of testosterone. With the decline in plasma LH, as photorefractoriness develops, the steroidogenic features of the cells of Leydig undergo disorganization. For as yet unexplainable reasons the plasma levels of testosterone decline before the decrease in plasma LH and before the degeneration of the steroidogenic features of the cells of Leydig.     

Circadian and masking control of migratory restlessness in Gambel's white-crowned sparrow (Zonotrichia leucophrys gambelii)

Avian migration is a seasonal activity that requires intricate timing on both an annual and daily basis. With increasing evidence for endogenous regulation of daily activities in migrant species, we tested whether a circadian oscillator may be involved with the expressions of daily locomotor activities and specific behaviors of the long-distance migrant, Gambel's white-crowned sparrow (Zonotrichia leucophrys gambelii). Our previous studies have identified both daytime and nighttime behavioral patterns under a photoperiod of 18L:6D. In 2 separate trials, birds in the vernal migratory life-history stage were exposed to constant dim light, (DD)dim, and constant bright light, LL, while locomotor activity and behavioral observations were collected. Under (DD)dim, the daytime behaviors that included active and quiescent components observed under 18L:6D were lost as migratory restlessness, the intense nighttime activity, persisted nonstop for 36.4 h. Furthermore, the specific behaviors of migratory restlessness that are normally confined to the dark phase of 18L:6D, beak-up and beak-up flight, were expressed also during the subjective day of (DD)dim. Birds exposed to LL retained similar patterns of activity to the 18L:6D condition for 3 days, after which they became arrhythmic. Behavioral observations of intense locomotor activity observed during the subjective night of LL revealed no beak-up and beak-up flight. Thus, the complete expression of migratory restlessness that includes beak-up and beak-up flight may not be regulated by a circadian oscillator but instigated by very low light intensity. Locomotor activity and associated daytime behaviors appear to be influenced by a circadian oscillator, given their persistent patterns under LL. Therefore, we suggest that the separate components of migratory behavior are regulated differentially by a circadian oscillator and ambient lighting conditions.     

Investigations of the butylcholinesterase-containing cells of the adenohypophysis of the white-crowned sparrow,Zonotrichia leucophrys gambelii

Summary In the adenohypophysis of Zonotrichia leucophrys gambelii two types of cells with butylcholinesterase(BuChE) activity can be demonstrated histochemically. Type I occurs in the cephalic lobe of the pars distalis and in the pars tuberalis; it consists of oval and round cells. It is a distinctive cell type that is identical with the amphophilic cells described by Matsuo, Vitums, King and Farner (1969). Whereas castration or inhibition of thyroid gland activity causes only minor changes in these cells, blocking of adrenal cortex activity, or adrenalectomy, causes conspicuous hyperplasia and hypertrophy suggesting that these cells are involved in the production or release of ACTH. The second type, which occurs in both cephalic and caudal lobes, consists mostly of irregularly formed cells. Various observations indicate that it is a composite group, consisting, at least in part, of degenerating cells.These investigations were supported by grants from the National Institutes of Health (S ROI NB 06812) and the National Science Foundation (GB 5969) to Professor Farner.     

Electron microscopic and experimental studies of the pineal organ in the white-crowned sparrow,Zonotrichia leucophrys gambelii

Summary The structure of the pineal organ of Zonotrichia leucophrys gambelii, as revealed by light- and electron-microscopy, resembles that of Passer domesticus (Oksche and Kirschstein, 1969; Ueck, 1970). The typical cellular element is the pinealocyte with certain basic structural features of the pineal photoreceptors of lower vertebrates (see Oksche, 1971). However, instead of the characteristic, cone-like outer segments, there are, as in other species of birds, only bulbous cilia with ectopic whorls of lamellae. This structure of the outer segment is, in a sense, contrary to the demonstration of synaptoid contacts, numerous unmyelinated, and occasional myelinated nerve fibers by electron microscopy. In Nissl preparations it was possible to demonstrate typical nerve cells. The pinealocytes of Z. l. gambelii are secretory; their Golgi complex forms granulated vesicles (800–1,400 Å in diameter) that belong to the group of granular inclusions characteristic of monoamines. Autonomie nerve fibers course within the connective tissue capsule of the pineal organ. In many pinealocytes of Z. l. gambelii, the granular endoplasmic reticulum contains extensively expanded cisternae that are filled with a flocculent material and closely associated with bundles of filaments. In a number of cases such loop-like structures are selectively stainable with aldehyde fuchsin. It was not possible to demonstrate specific secretory activity in the supporting cells. Extirpation of the pineal organ in Z. l. gambelii had no definitely detectable influence on the photoperiodic control of testicular growth.Aves, Passeriformes, Fringillidae.Supported by grants from the Deutsche Forschungsgemeinschaft to Professor Oksche and by the National Science Foundation (GB 11905) to Professor Farner. A part of this investigation was effected while Professor Kobayashi held a Visiting Professorship at the University of Giessen.     

The tubero-infundibular neuron system: a component of the photoperiodic control mechanism of the white-crowned sparrow,Zonotrichia leucophrys gambelii

Summary To assess the roles of the hypothalamic neurosecretory and tubero-infundibular neuron systems in the mechanism of photoperiodic control of testicular growth in Zonotrichia leucophrys gambelii, midline electrolytic lesions were created in the median eminence, in its individual divisions, and in the region of the infundibular nucleus. Radiography was employed to facilitate the stereotaxic placement of lesions. Extensive damage to the neurosecretion-rich anterior division of the median eminence neither prevented the initiation of testicular growth in photosensitive, photostimulated birds nor induced gonadal regression in birds in which gonadal growth had previously been initiated by natural photoperiodic stimulation. Likewise, there was no impairment of the gonadotropin release mechanism when damage was restricted primarily to the neurosecretion-deficient posterior division of the median eminence. However, in birds in which the zone of damage included both divisions of the median eminence, the photoperiodic testicular response was abolished or markedly suppressed; if testicular growth had been initiated prior to electrocoagulation of the median eminence, testicular regression was induced. Gonadotropic insufficiency comparable to that induced by lesions in the median eminence was caused also by large lesions in the region of the infundibular nucleus or by smaller ones restricted primarily to its median, basal portion. Zones of damage that impair gonadotropic function thus correspond to (a) the chief nucleus of origin of the tubero-infundibular tract, (b) the principal route of entry of tubero-infundibular fibers into the anterior and posterior divisions of the median eminence, and (c) the terminal distribution of tubero-infundibular fibers in the eminential zones of neurovascular contact. These observations suggest that the tubero-infundibular neuron system is an essential component of the photoperiodic control mechanism of Z. leucophrys gambelii and are consistent with an hypothesis that assigns to this parvicellular neuron system the production of a neurohormone that regulates the release of a growth-stimulating gonadotropin from the pars distalis. The failure of anterior median eminence lesions to eliminate gonadotropin release is inconsistent with the hypothesis that the eminential component of the hypothalamic neurosecretory system is an essential element of the mechanism that controls photoperiodic testicular growth.This investigation was supported by a research grant (NB 01353) to Professor Donald S. Farner from the National Institutes of Health. A portion of the research was conducted while the author held the William T. Porter Fellowship of The American Physiological Society. I am grateful to Professor Farner for his suggestions and criticisms.This paper is based on a thesis submitted in partial fulfillment of the requirements for the Ph. D. in Zoophysiology at Washington State University. Portions of this study have been published previously in abstract form (F. E. Wilson and Farner, 1965).     

The ACTH-immunoreactive system in the brain of the white-crowned sparrow,Zonotrichia leucophrys gambelii (Passeriformes,Emberizidae)

Summary The ACTH-immunoreactive (ir) system of the avian brain is particularly conspicuous in the male white-crowned sparrow (Zonotrichia leucophrys gambelii). The irperikaryal population is concentrated mainly within the tuberal region, projecting primarily in a dorsal direction: (i) into the striatum; (ii) into rostral diencephalic, septal, hyperstriatal, and thalamic areas; and (iii) into dorsal and ventral areas of the brain stem. Ir-fibers seemingly contact local non-immunoreactive neurons mainly in the accumbens nucleus, septum, dorsal thalamic nuclei, infundibular and interpeduncular nuclei, and in the rostral diencephalon. Neurohemal zones are not supplied by ACTH-ir terminals. Immunocytochemical problems arising from the complexity of the proopiomelanocortin molecule and its derived peptide components are discussed in relation to phylogenetically directed studies, and contradictory results.Dedicated to Professor Dr. T.H. Schiebler on the occasion of his 65th birthday     

The ACTH-immunoreactive system in the brain of the white-crowned sparrow, Zonotrichia leucophrys gambelii (Passeriformes, Emberizidae)

The ACTH-immunoreactive (ir) system of the avian brain is particularly conspicuous in the male white-crowned sparrow (Zonotrichia leucophrys gambelii). The irperikaryal population is concentrated mainly within the tuberal region, projecting primarily in a dorsal direction: (i) into the striatum; (ii) into rostral diencephalic, septal, hyperstriatal, and thalamic areas; and (iii) into dorsal and ventral areas of the brain stem. Ir-fibers seemingly contact local non-immunoreactive neurons mainly in the accumbens nucleus, septum, dorsal thalamic nuclei, infundibular and interpeduncular nuclei, and in the rostral diencephalon. Neurohemal zones are not supplied by ACTH-ir terminals. Immunocytochemical problems arising from the complexity of the proopiomelanocortin molecule and its derived peptide components are discussed in relation to phylogenetically directed studies, and contradictory results.     

Hormonal, behavioral, and thermoregulatory responses to bacterial lipopolysaccharide in captive and free-living white-crowned sparrows (Zonotrichia leucophrys gambelii)

Exposing vertebrates to pathogenic organisms or inflammatory stimuli, such as bacterial lipopolysaccharide (LPS), activates the immune system and triggers the acute phase response. This response involves fever, alterations in neuroendocrine circuits, such as hypothalamo-pituitary-adrenal (HPA) and -gonadal (HPG) axes, and stereotypical sickness behaviors that include lethargy, anorexia, adipsia, and a disinterest in social activities. We investigated the hormonal, behavioral, and thermoregulatory effects of acute LPS treatment in a seasonally breeding songbird, the white-crowned sparrow (Zonotrichia leucophrys gambelii) using laboratory and field experiments. Captive male and female sparrows were housed on short (8L:16D) or long (20L:4D) day lengths and injected subcutaneously with LPS or saline (control). LPS treatment activated the HPA axis, causing a rapid increase in plasma corticosterone titers over 24 h compared to controls. Suppression of the HPG axis occurred in long-day LPS birds as measured by a decline in luteinizing hormone levels. Instead of a rise in body temperature, LPS-injected birds experienced short-term hypothermia compared to controls. Birds treated with LPS decreased activity and reduced food and water intake, resulting in weight loss. LPS males on long days experienced more weight loss than LPS males on short days, but this seasonal effect was not observed in females. These results paralleled seasonal differences in body condition, suggesting that modulation of the acute phase response is linked to energy reserves. In free-living males, LPS treatment decreased song and several measures of territorial aggression. These studies highlight immune-endocrine-behavior interrelationships that may proximately mediate life-history tradeoffs between reproduction and defense against pathogens.     

Seasonal changes in the reproductive system of the female white-crowned sparrow,Zonotrichia leucophrys gambelii,in captivity and in the field

Summary The ventral apterium of free-living female White-crowned Sparrows (Zonotrichia leucophrys gambelii) becomes an incubation patch during the breeding season. At this time, it loses its feathers, increases in wet and defatted dry weight, and undergoes marked histological alterations. At times of year other than the breeding season, the apterium consists of a low squamous epidermis and a thin, poorly vascularized dermis of dense connective tissue. The dermis is separated from subcutaneous tissue by an internal elastic lamina. During the breeding season, the epidermis is a proliferative, stratified squamous eptihelium with well-defined basal, intermediate, transitional, and cornified layers; and the dermis consists of a superficial layer of collagen and a deep layer of highly vascular areolar connective tissue, noticeably edematous and mildly inflamed. Blood vessels are frequently in large groups in the center of the dermis. Edema and hypervascularity are most pronounced during incubation, but the epidermis is best developed during egg-laying. The apterium reverts to its basal state after the incubation period. Captive females, which do not breed, do not develop incubation patches.Estrogen is apparently responsible for feather loss and collagen synthesis. It and other unidentified hormones (probably prolactin and/or androgens) produce the hypervascularity, edema, and epidermal growth.This study was supported by an NIH Training Grant (GM 01276) from the National Institute of General Medical Sciences and by funds from the Faculty Research Council at Fordham University, New York, N.Y. It is a pleasure to acknowledge the assistance of Drs. Brina Kessel and George West at the University of Alaska during summer, 1968; Dr. William A. deGraw for help in the field; and Drs. Laura Englisch and James Wiggins, as well as my son, Robert, for help with the photomicrography. Wallace Moreland of the Singer-Friden Company kindly provided a desk calculator for my use. The content of this paper profitted substantially from the suggestions of Dr. Robert A. Lewis. This paper is based on part of a dissertation done to fulfill the Ph.D. requirements at Washington State University     

Projection of fibers immunoreactive to an antiserum against gonadoliberin (LHRH) into the pineal stalk of the white-crowned sparrow,Zonotrichia leucophrys gambelii

Summary We have demonstrated a bundle of fibers, immunoreactive to an antiserum against gonadoliberin (luteinizing hormone-releasing hormone), that projects into the pineal stalk of photostimulated male Z. l. gambelii, a photoperiodic passerine species. These fibers have their origin in the dorsal division of the column of gonadoliberin-positive perikarya that extends caudodorsally from the ventromedial preoptic area to the level of the anterior commissure. After entering the habenula these fibers can be traced into the pineal stalk. This bundle is of interest because it apparently has not previously been reported in birds, and further, because the pineal body of this species is not known to have a role in the photoperiodic induction of increased rates of release of gonadotropins. Relationships of this bundle to other components of the gonadoliberin system are described briefly.     

The distribution of monoamine oxidase and acetylcholinesterase in the hypothalamus and its relation to the hypothalamo-hypophysial neurosecretory system in the white-crowned sparrow,Zonotrichia leucophrys gambelii

Summary The distribution of monoamine-oxidase and acetylcholinesterase activities in the hypothalamus of the White-crowned Sparrow has been studied in relation to the hypothalamohypophysial neurosecretory system. The enzyme activities, as revealed by the methods employed, are unaffected during photoperiodically induced testicular growth. Monoamine oxidase has a distribution distinctly different from that of the aldehyde-fuchsin positive neurosecretory material in that there is high activity in the peripheral palisade layers of both the anterior and posterior divisions of the median eminence. Intimate contact is made between these areas with the primary vessels of the hypophysial portal system. A second concentration of activity lies in a layer between the ependymal cells and the neurosecretory material of the fiber tract. In general, monoamine oxidase appears to be associated with glial elements and non-neurosecretory axons. The pars nervosa has little or no monoamine-oxidase activity. The distribution of acetylcholinesterase activity in the anterior division of the median eminence is very similar to that of the aldehyde-fuchsin positive neurosecretory neurons; however, acetylcholinesterase also occurs in the posterior division without associated neurosecretory fibers. These distribution of enzyme activities are considered in relation to possible adrenergic and cholinergic mechanisms in the median eminence.Dedicated to Professor Berta Scharrer in honor of her 60th birthday.Supported by grant NB-01353 from the National Institutes of Health to Professor Farner. This investigation was conducted while Doctor Kobayashi was a National Science Foundation Senior Foreign Scientist at Washington State University. We are indebted to Doctor Christian Da Lage, Laboratoire de Histologie, Falculté de Médecine de Paris, for the preliminary development of some of the techniques used in these investigations.     

Endocrine correlates of alternative phenotypes in the white-throated sparrow (Zonotrichia albicollis)

Many vertebrate species exhibit alternative phenotypes (or morphs), in which one sex displays phenotypic variation equal to or greater than the variation between the sexes. Males in such species typically display differences in reproductive strategies and morphology. Steroid hormones such as testosterone are known modulators of reproductive behavior and morphology and therefore are obvious candidates for the mediation of phenotypic differences between morphs. We conducted a year-round study in the white-throated sparrow (Zonotrichia albicollis) that exhibits alternative phenotypes in plumage coloration and behavior in both sexes: during the breeding season, white-striped males and females are more aggressive and have higher song rates than tan-striped individuals. At the beginning of the breeding season, free-living white-striped males had higher plasma testosterone concentrations than tan-striped males. However, this finding might have been due to different social experiences because captive male morphs sampled at similar times of year did not differ in testosterone concentrations. Captive white-striped males had larger testis and cloacal protuberance sizes than tan-striped males, which might be related to the divergent mating strategies of the morphs. Male morphs showed similar increases in luteinizing hormone following injections of gonadotropin-releasing hormone, but white-striped males showed larger increases in testosterone, indicating differences between morphs in gonadal testosterone production. Females had low concentrations of testosterone, and morphs did not differ. Plasma dehydroepiandrosterone (DHEA) concentrations were elevated in both sexes and morphs during the breeding and non-breeding seasons. These data do not support the hypothesis that testosterone activates behavioral differences between alternative phenotypes in the white-throated sparrow. Alternative testable hypotheses include hormonal effects during early development and direct genetic effects.     

The effect of flight, fasting and p,p'-DDT on thyroid hormones and corticosterone in Gambel's white-crowned sparrow, Zonotrichia leucophrys gambelli

This study examined the effects of p,p'-dichlorodiphenyltrichloroethane (p,p'-DDT), fasting and flight on thyroid hormones and corticosterone in Gambel's White-crowned Sparrows (Zonotrichia leucophrys gambelli). Female sparrows were dosed daily with either 5 mg p,p'-DDT per kg body mass or corn oil vehicle over 3 days. On the fifth day the sparrows were divided into 3 groups: (1) unstressed - non-stressed control sparrows; (2) fasted - sparrows fasted for intervals ranging from 20 min to 9 h; or (3) flown - sparrows flown in a wind tunnel for intervals between 20 min and 2.5 h while fasting. Half the sparrows from each group received DDT (DDT-dosed sparrows) and the other half corn oil vehicle only (vehicle sparrows). Trunk blood plasma was analyzed for thyroxine, triiodothyronine and corticosterone using radioimmunoassay. In the flown group, corticosterone was elevated (DDT-dosed 35.52 ng/ml, P < or = 0.05), and thyroxine was depressed (DDT-dosed 4.09 ng/ml, P < or = 0.05; vehicle 4.33 ng/ml, P < or = 0.05). Elevated corticosterone likely decreased thyroid hormone production through a negative feedback mechanism originating at the hypothalamus. Mean triiodothyronine concentrations did not differ among any of the test groups. Relative to time fasted and flown, thyroxine decreased in flown birds dosed with DDT (P < 0.001) and triiodothyronine decreased in fasted birds dosed with DDT (P = 0.004). The increased rate of hormone diminution may be a result of the ability of DDT to induce microsomal enzyme production.