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In golden hamsters, vasopressin (AVP) microinjected within the ventrolateral hypothalamus (VLH) facilitates offensive aggression. As serotonin is known to inhibit offensive aggression, we decided to test whether AVP-facilitated behavior is also inhibited by serotonin treatment. Testosterone-treated male golden hamsters received IP injections of fluoxetine, a serotonin reuptake inhibitor, or vehicle 1 h prior to AVP microinjections within the VLH. The animals were tested for offensive aggression in a resident-intruder model after the microinjections, and the results were compared between groups. Pretreatment with fluoxetine inhibited AVP-facilitated offensive aggression. Only one out of nine fluoxetine-treated animals attacked and bit the intruders, compared to six out of seven vehicle-treated animals. Furthermore, we also confirmed by in vitro autoradiography that the VLH contains vasopressin V(1) and serotonin 5-HT1B receptors. Therefore, it is possible that serotonin may inhibit AVP-facilitated offensive aggression by acting directly at the level of the VLH as well as at other sites.

In rats, small (diameter: ca. 10 micrograms) vasopressinergic neurons have been localized in the forebrain, including extrahypothalamic sites, such as the bed nucleus of the stria terminalis (BST) and the medial amygdala (MeA). In golden hamsters, no such neurons have ever been described in extrahypothalamic sites, while their presence in some hypothalamic sites, such as the paraventricular nucleus (PVN), remains controversial. The present studies were carried out to confirm the existence of small vasopressinergic neurons in the forebrain of golden hamsters, using rats as a positive control. The presence of small vasopressinergic neurons in these sites was first tested by immunocytochemistry in colchicine-treated animals. The resulting distribution was corroborated by in situ hybridization for vasopressin (AVP) mRNA. While a large number of small AVP-immunoreactive (AVP-ir) neurons was found in the BST and MeA of colchicine-treated rats, none was found in the same locations in hamsters. Interestingly, as a few large (diameter: 20-25 micrograms) AVP-ir neurons were found in the BST just medial to the small neurons in rats, the same area contained a few large and small AVP-ir neurons in hamsters. In the PVN, large and small AVP-ir neurons were found in rats and hamsters. However, three to four times more neurons were counted in rats. These data were confirmed by in situ hybridization. Indeed, in hamsters, no labelling for AVP mRNA was detected in small neurons within the BST and MeA. Furthermore, the PVN of rats contained more labelling for AVP mRNA, as compared to hamsters. These results confirm that the distribution of vasopressinergic neurons in rats cannot be generalized to other species without a detailed analysis.

Vasopressin (AVP) receptor binding within hypothalamic sites was compared between cycling and lactating female golden hamsters. The density of AVP receptor binding was analyzed by quantitative autoradiography within the ventrolateral hypothalamus and dorsomedial hypothalamic nucleus. Lactation was correlated with a disappearance of AVP receptor binding within the ventrolateral hypothalamus. In contrast, lactation was associated with a two- to three-fold increase in the density of AVP receptor binding within the dorsomedial hypothalamic nucleus. These results suggest that AVP receptor binding within the ventrolateral hypothalamus is responsive to gonadal hormones in female golden hamsters. However, the increase in binding observed within the dorsomedial hypothalamus may be related to other neurobiological changes associated with lactation.

In the following studies, the presence of a sexual difference in arginine-vasopressin (AVP) receptor binding was tested within the ventrolateral hypothalamus (VLH), an area rich in gonadal steroid receptors. The density of AVP receptor binding was estimated by in vitro quantitative autoradiography within the entire rostro-caudal extent of the VLH. The density of AVP binding was higher in males than in females at all levels of this area. Furthermore, dependency on testosterone treatment was also compared between gonadectomized males and females. While gonadectomy resulted in a near total disappearance of binding in both males and females, testosterone treatment resulted in equally high levels of binding in both sexes. Indeed, a high density of AVP receptor binding was observed at all levels of the VLH in both testosterone-treated males and females. These results show that adult female golden hamsters are equally capable as males of expressing high levels of AVP receptor binding in the VLH in response to high levels of testosterone. Together, our results suggest that, while AVP receptor binding within the VLH is sexually different in gonadally-intact animals, these differences are not related to differential responsiveness to testosterone, but rather to a differential production and availability of the hormone.

Adult golden hamsters, as compared to rats, lack several parvicellular vasopressinergic cell groups. We looked at the development of the vasopressinergic system in hamsters to draw comparisons with maturing rats. Arginine-vasopressin-immunoreactive (AVP-ir) neurons, their fibers and associated AVP binding sites were observed at several intervals after birth. Different rates of maturation were observed between different populations of vasopressinergic neurons. Within the suprachiasmatic nucleus (SCN), small AVP-ir neurons, their fibers and related binding sites maturated gradually during the first month after birth. In comparison, large AVP-ir neurons were apparent in newborn animals. Similarly, AVP-ir fibers and AVP binding sites were also present in the brain of newborns within areas not related to small vasopressinergic neurons from the SCN, such as the central amygdala (CeA) or the cerebral cortex. During the following weeks, a heterogenous pattern of development was observed within such areas. As the neurosecretory vasopressinergic system appeared to develop gradually, projections to the brain and their associated binding sites developed rapidly during the first week of life. Transient patterns of maturation were observed within certain sites. Indeed, some of the labelling observed in newborns regressed later. As similar reports were made in rats, our observations draw analogies between the vasopressinergic systems of these two species, beside their apparent dissimilarities in adult animals. Furthermore, our data also reinforce the concept that large vasopressinergic neurons do not constitute a homogenous population.

In golden hamsters, microinjections of arginine vasopressin (AVP) within the anterior hypothalamus (AH) and lateral septum (LS) elicit the display of a stereotyped behavior: flank marking. As these areas are reciprocally connected, we tested whether AVP-sensitive sites constitute an organized network. Flank marking was recorded in animals with ibotenic acid lesions within the AH or LS after AVP injections within the LS or AH. While AVP injections in the AH and LS induced high flank-marking scores, certain lesions blocked the behavior. Lesions of the LS failed to affect flank marking induced by injections within the AH. In contrast, unilateral AH lesions blocked flank marking induced either by LS injections or AH injections in the contralateral side. These results suggest that the bilateral integrity of the AH is critical for the activation of flank-marking behavior by AVP. Together, these data suggest that the AH is an important relay of the neural network controlling flank-marking behavior.

After being paired with females, male prairie voles show major changes in their social behaviors among which is an increase in paternal responsiveness. These changes are accompanied by fluctuations in the density of the [Arg8]vasopressin-immunoreactive (AVP-ir) fibers in the lateral septum, suggesting that septal AVP might be involved in these changes. To explore a possible involvement of septal AVP in paternal responsiveness, we tested whether injections of saline, AVP, or the V1a receptor antagonist [1-(beta-mercapto-beta, beta-cyclopentamethylenepropionic acid),2-(O-methyltyrosine]AVP [d(CH2)5Tyr(Me)AVP] into the lateral septum influenced the four most prominent paternal activities displayed by male prairie voles; grooming, crouching over, contacting, and retrieving pups. In a first experiment, sexually inexperienced males received a single injection of AVP, saline, or d(CH2)5Tyr(Me)AVP in the lateral septum, after which their paternal responsiveness was recorded during a 10-min period. AVP-injected animals spent more time contacting and crouching over pups, while d(CH2)5Tyr(Me)AVP-injected animals spent less time grooming pups than saline-injected animals. In a follow-up study, one group of animals received an injection of AVP preceded by an injection of saline or d(CH2)5Tyr(Me)-AVP into the lateral septum. A second group of animals received an injection of saline preceded by an injection of saline or d(CH2)5Tyr(Me)AVP into the lateral septum. In both groups, animals spent less time grooming, crouching over, and contacting pups if they had first been injected with d(CH2)5Tyr(Me)AVP. Control experiments suggested that the effects of AVP on paternal responsiveness were dose- and site-specific. These data suggest that septal AVP enhances paternal responsiveness by a V1a receptor-mediated mechanism.

In hamsters, dominant/subordinate relationships are initially determined by overt aggression, but subsequently communicated by flank marking, an arginine vasopressin (AVP)-dependent behavior. Once a relationship is established, dominant males will flank mark at a higher frequency than their subordinate partners. Flank marking displayed during social encounters can be turned "on or off" by microinjection of AVP or AVP-receptor antagonist within the anterior hypothalamus (AH). For instance, microinjecting dominant hamsters with AVP-receptor antagonist blocks their flank marking and provokes an immediate induction of flank marking by subordinate animals. The central effects of AVP have been extended to include a role in offensive aggression. Microinjection of AVP-receptor antagonist into the AH inhibits the aggression of a resident hamster toward an intruder and diminishes aggression between hamsters placed into a neutral arena. Microinjection of AVP into the ventrolateral hypothalamus (VLH) facilitates offensive aggression of a resident toward an intruder. As AVP receptors in the VLH are testosterone-dependent, it is possible that the reduction of aggression observed in castrated hamsters is due to a loss of AVP responsiveness in the VLH. Recent work has focused on the notion that serotonin (5-HT) antagonizes AVP activity in the CNS. The AH and VLH have a high density of 5-HT terminals and binding sites. Indeed, there appear to be 5-HT synapses on AVP neurons in the AH. Microinjection of 5-HT into the AH inhibits AVP-induced flank marking while IP injection of fluoxetine a serotonin reuptake inhibitor inhibits AVP-induced offensive aggression in the VLH. It is possible that serotonin interacts with AVP to modulate offensive aggression.

Golden hamsters, as compared to rats, lack several parvicellular vasopressinergic cell groups, particularly sexually dimorphic populations. We decided to test the possibility that magnocellular vasopressinergic neurons are subjected to sexual differences in hamsters, as they are known to display vasopressin (AVP)-dependent sexually dimorphic behaviors. The distribution of magnocellular vasopressinergic neurons was mapped and compared between males and females. Approximately 50% more vasopressin-immunoreactive (AVP-ir) neurons were counted in males within the medial and lateral divisions of the supraoptic nucleus. Furthermore, levels of AVP extracted from the hypothalamus and the pituitary gland were three to four times higher in males than in females. Finally, hypothalamic extracts from a male and a female hypothalamus were fractionated by HPLC and assayed for AVP immunoreactivity. Immunoreactivity from each extract had the same retention time as synthetic AVP standards; and the levels were twice as high in the male. These results support the existence of sexual differences in the magnocellular vasopressinergic system in golden hamsters. These differences appear to be related to previously reported sexual differences in AVP secretion from the neurohypophysis.

An arginine-vasopressin (AVP) derivative, [d(CH2)5,Sar7]AVP (SAVP), has been characterized as an antagonist to vasopressin V1 receptors. Using AVP-dependent flank-marking behavior as a bioassay, it was possible to verify that iodinated SAVP (I-SAVP) retains biological activity within the central nervous system, as the antagonist blocked the behavior. Furthermore, 125I-SAVP was used to localize specific V1 binding sites in the brain. The resulting binding was localized to discrete anatomical sites, and highly specific to V1-like receptors. While we confirmed previous findings using 3H-AVP in golden hamsters, we also identified binding in many areas previously unreported (e.g., arcuate and paraventricular nuclei of the hypothalamus, tenia tecta, posteromedial cortical nucleus of the amygdala, and zona incerta), suggesting that 125I-SAVP provides a greater level of resolution. In addition, specific binding was observed in the lateral septum, anterior hypothalamus, and midbrain central gray, areas that have previously been shown to trigger flank marking in response to AVP microinjection. The presence of AVP binding sites in limbic and mesencephalic areas involved in the regulation of flank marking suggests that this neuropeptide may play an important role as a neurotransmitter at multiple levels in the neural circuits controlling this behavior.

The distribution of corticotropin-releasing hormone-immunoreactive (CRH-IR) neurons and fibers was observed in golden hamsters. CRH-IR neurons and fibers were observed within the hypothalamus, thalamus, amygdala, cortex, midbrain, and hindbrain. The largest numbers of CRH-IR neurons were seen within the magno- and parvocellular divisions of the paraventricular nucleus of the hypothalamus and within the septum, bed nucleus of the stria terminalis, preoptic area continuum. The highest density of immunoreactive fibers was observed in the external zone of the median eminence. In addition, many immunoreactive fibers were observed within the bed nucleus of the stria terminalis and the preoptic area. The distribution obtained in hamsters was compared with previously reported distributions from rats, and both were generally similar.

The present study was done to determine whether the vasopressinergic neurons in the hypothalamus controlling flank marking behavior are distinct from the magnocellular neurons comprising the hypothalamo-neurohypophysial system. Animals were either hypophysectomized or injected with a suicide transport lectin, volkensin, into the neurohypophysis. Both procedures resulted in a pronounced loss of vasopressin-immunoreactive perikarya throughout the hypothalamus concomitant with increases in water intake and urine output and decreases in circulating levels of vasopressin. The loss of the hypothalamo-neurohypophysial system was most pronounced in volkensin-treated animals that presented with frank diabetes insipidus and exceedingly low levels of plasma vasopressin. However, the vasopressinergic fibers and magnocellular neurons in and around the anterior hypothalamus implicated in the control of flank marking survived the volkensin treatment. Volkensin-treated animals exhibited levels of flank marking typical of untreated animals. These data suggest the presence of anatomically and functionally distinct populations of vasopressinergic magnocellular neurons in the hypothalamus of the golden hamster.

Abstract Site-, context- and dose-dependent actions of intrahypothalamic cortisol administration on the agonistic behaviors of adult male golden hamsters (n = 128 dyads) were examined. When cortisol-treated animals were tested in paired encounters with aggressive cholesterol-treated opponents, chronic (>/= 24 h) cortisol treatment (1 mm implants) induced significant (P < 0.05) submission in three medial hypothalamic areas (anterior hypothalamic area > medial preoptic area > ventromedial hypothalamus), but aggression in the paraventricular nucleus or third ventricle. In contrast, chronic cortisol treatment in the anterior hypothalamic area resulted in high levels of aggression during paired encounters with submissive opponents, and during territorial aggression tests with juvenile male intruders. Acute (>/= 20 min) cortisol treatment in the anterior hypothalamic area (100 nl injections) induced significant submission after 10(-2) M, but significant aggression after 10(-6) M microinjections in paired encounters with aggressive vehicle-injected opponents. These findings suggest glucocorticoid-sensitive mechanisms within the anterior hypothalamus modulate aggressive responding during intrasexual social encounters.

The agonistic behaviors of adult male golden hamsters (N = 108 dyads) were examined 5 min after stereotaxic microinjection of adrenal and gonadal steroids into the anterior hypothalamus. Flank marks, attacks, bites, and retreats were scored over a 15 min test period during which steroid-injected animals were paired in a neutral arena with vehicle-injected conspecifics. Animals microinjected with either 10(-6) M cortisol or 10(-6) M beta-estradiol displayed significantly (p less than 0.05) higher levels of flank marking than other steroid-treated animals. Animals microinjected with 10(-6) M cortisol displayed significantly higher levels of aggression than their opponents. In contrast, the behavior of the vehicle-injected animals paired with 10(-6) M cortisol-treated opponents was characterized by submissive responding. This profile of the 10(-6) M cortisol treatment, i.e., promoting aggression in a steroid-treated animal while eliciting submission from its vehicle-treated opponent, was not observed in pairs in which steroid-injected animals were treated with equimolar concentrations of testosterone, dihydrotestosterone, progesterone, beta-estradiol, or deoxycorticosterone. These findings suggest steroids exert immediate effects on agonistic responding in the anterior hypothalamus of male hamsters. The immediate action(s) of cortisol appear to include facilitating aggression and flank marking, while the immediate action(s) of beta-estradiol appears to be confined to the communicative aspect of agonistic responding in this species.

The purpose of the present study was to characterize the hormonal response of dominant and submissive male hamsters to acute and repeated exposure to social conflict. We found that submissive, but not dominant, males exhibited elevated plasma levels of adrenocorticotropin (ACTH), cortisol, and beta-endorphin (beta-EP) following one exposure to an agonistic encounter. After five exposures to a dominant opponent, submissive males showed smaller, but still significant, elevations in these plasma hormones. After nine exposures, submissive hamsters showed significant elevations only in plasma ACTH and beta-EP. Plasma testosterone was significantly suppressed in submissive males that fought nine times. We conclude that hamsters are a useful species with which to study the neuroendocrine correlates of social behavior.

The ingestion of a meal high in fat content is known to increase circulating levels of neurotensin (NT) in humans. However, the magnitude of the postprandial rise of NT in the general circulation and its physiological significance have been subject of much debate. The present study examines circulating levels of NT in male volunteers prior to and following each of their three daily meals (ca. 31 g fat/meal). The response observed are also compared to that elicited by the direct instillation of intralipid (ca. 44 g fat) into the duodenum. NT levels were determined by radioimmunoassay of acid/acetone extracted plasma fractionated by high pressure liquid chromatography. Meals caused a significant but modest increase in NT levels, with the largest increment (ca. 4 fmol/ml) occurring after breakfast. In contrast, NT levels increased ca. 20 fmol/ml with intraduodenal instillation of lipid. The meal-stimulated increases in circulating NT measured here are 4- to 5-fold less than those reported by others, the difference most likely reflecting the lesser amount of lipid ingested. Previous studies provided subjects with single meals containing in excess of 120 g of fat; the 30 g of fat ingested by our subjects, ca. 33% of total caloric intake, is near that recommended by the U.S. Senate, Select Committee on Nutritional and Human Needs. These data show that diets with a reasonable fat content have only a modest effect on circulating levels of NT.

The present study examined whether gonadal hormones or photoperiodic control influence arginine-vasopressin (AVP) immunoreactivity in the Syrian hamster (Mesocricetus auratus) as has been reported in several other rodent species. Male hamsters were castrated or sham-castrated and exposed to LD 14/10 or LD 6/18 for 13 weeks. Photoperiod and castration significantly altered body weight and the levels of circulating testosterone. In sham-castrates, testis width was significantly reduced in hamsters housed in LD 6/18. In contrast, photoperiod and castration produced no detectable alterations in AVP immunoreactivity in various CNS sites including the bed nucleus of the stria terminales, the lateral septum and medial preoptic-anterior hypothalamus when measured by immunocytochemistry and radioimmunoassay of tissue punches. These data provide no evidence that AVP is regulated by either gonadal hormones or photoperiodic mechanisms in the Syrian hamster.

Tritiated arginine8-vasopressin [( 3H]AVP) was used to identify specific binding sites for this neuropeptide in the CNS of the golden hamster. [3H]AVP binding sites were concentrated in the dorsal, ventral and lateral septum, bed nucleus of the stria terminalis (BNST), central amygdala, hippocampus, dorsal thalamic nuclei, anterior cingulate gyrus and endopiriform nucleus. Septal-BNST [3H]AVP binding sites were further characterized using membrane preparations. Saturation analysis in septal-BNST membranes resulted in a Bmax of 12.4 +/- 0.82 fmol/mg protein and a Kd of 2.5 +/- 0.36 nM. Pharmacological studies indicate that the binding site in the septum-BNST membranes shows selectivity similar to a V1-type vasopressin receptor. Binding characteristics were similar to those obtained from crude septal membranes prepared from adult Long-Evans rat.

Microinjection of arginine vasopressin into the lateral septum and bed nucleus of the stria terminalis of male hamsters stimulates intense flank marking and flank gland grooming, while microinjections of vasopressin in sites immediately adjacent to these areas or in the lateral ventricle are ineffective. Microinjections of oxytocin, angiotensin II and the behaviorally active C-terminal fragment of vasopressin, metabolite neuropeptide, by comparison, do not stimulate flank marking. Effective sites for vasopressin injection are clearly superimposable upon autoradiographically defined sites of high V1-receptor density. Furthermore, vasopressin-sensitive neurons in the lateral septum and bed nucleus of the stria terminalis are necessary for the expression of naturally elicited flank marking since the microinjection of a V1-receptor antagonist into these sites was able to temporarily block flank marking triggered by odors from conspecifics.

Abstract It is well established that flank marking behavior in the Golden hamster is controlled by vasopressin-sensitive neurons localized to the anterior hypothalamus; however, the source(s) of vasopressinergic innervation to this area is unknown. Previous analysis by immunocytochemistry showed distinct populations of vasopressinergic magnocellular neurons localized to the supraoptic nucleus, paraventricular nucleus and the nucleus circularis that did not project to the neurohypophysis. In the present study, these same hypothalamic nuclei were lesioned by microinjection of kainic acid to determine which, if any, of these populations of vasopressin neurons are involved in the control of flank marking. Unilateral lesions in the areas of the nucleus circularis and supraoptic nucleus at the rostro-caudal plane of the anterior hypothalamus abolished odor-induced flank marking behavior. Lesions in the paraventricular nucleus at the level of the anterior hypothalamus did not consistently inhibit flank marking, while lesions of magnocellular neurons rostral or caudal to the anterior hypothalamus were ineffective. The microinjection of vasopressin into the anterior hypothalamus following lesion of the paraventricular and supraoptic nuclei stimulated flank marking, evidence that treatment with kainic acid did not damage the efferent component of this behavior. However, animals with lesions in the nucleus circularis did not respond to the microinjection of vasopressin; hence, it is uncertain whether lesions in this area disrupt vasopressinergic innervation to the anterior hypothalamus or simply destroy the motor neurons controlling flank marking. In summary, the data clearly demonstrate that vasopressin neurons localized primarily to the medial aspect of the supraoptic nucleus are necessary for sensory integration of odor-induced flank marking, and as such, may be one possible source of neurotransmitter controlling this behavior.

Abstract Vasopressin-sensitive neurons in the region of the anterior hypothalamus are necessary for the mediation of flank marking behavior in the Golden hamster. The precise nature of the vasopressinergic innervation to the anterior hypothalamus is unknown. In this study we seek to examine the potential sources of this innervation by mapping and counting the vasopressin-immunoreactive neurons that contribute to the hypothalamo-neurohypophysial system, and those that do not. Vasopressin-immunoreactive neurons in the hypothalamus were visualized by immunocytochemistry. Sections were mapped with a computer-aided microscope system, and labeled neurons counted. Two-dimensional maps were stacked into a three-dimensional wireframe model which could be manipulated for further examination. The average number of vasopressin neurons was 3,135, with over 60% of all perikarya localized to the lateral supraoptic nucleus. In a double-labeling study, neurons contributing to the hypothalamo-neurohypophysial system were retrogradely labeled by the injection of horseradish peroxidase into the neurohypophysis. The enzyme reaction product was visualized by treatment with tetramethylbenzidine followed by nickel-conjugated diaminobenzidine. Sections were subsequently stained for vasopressin by immunocytochemistry. Single- and double-stained neurons from serial sections were mapped and counted. Wireframe and contoured three-dimensional representations were generated. The average number of neurons projecting to the neurohypophysis was 5,619. However, an average of 981 neurons was immunoreactive to vasopressin but devoid of horseradish peroxidase. The greatest number of these non-projecting perikarya were found in and around the anterior hypothalamus, localized primarily in the lateral and medial aspect of the supraoptic nuclei, the ventral area of the paraventricular nucleus, and the nucleus circularis. By comparing the number of non-projecting neurons found by double-staining to the total cell count of the entire vasopressin system, it was estimated that approximately 30% of all vasopressin neurons in and around the anterior hypothalamus did not project to the neurohypophysis. Based on the distribution and localization of the non-projecting perikarya, it is speculated that these neurons may provide neurotransmitter for vasopressin-dependent flank marking in the male Golden hamster.

Golden hamsters with established dominant/subordinate relationships communicate their social status by rubbing pheromone-producing flank glands against objects in the environment. This behavior, called flank marking, is controlled by vasopressin-sensitive neurons localized to the anterior hypothalamus. Vasopressinergic magnocellular neurons in the nucleus circularis and medial aspect of the supraoptic nucleus are thought to be a source of neurotransmitter for the initiation of flank marking. The present study was undertaken to examine the extrahypothalamic control of flank marking. The anatomical and functional connections between the lateral septum and the vasopressin-containing nuclear groups in and around the anterior hypothalamus were examined by: (1) tracing afferent and efferent connections following microinjection of horseradish peroxidase and Phaseolus vulgaris-leucoagglutinin into the lateral septum, and (2) recording odor-induced flank marking prior to and following ibotenate lesions in the septum. The greatest number of perikarya retrogradely labeled with horseradish peroxidase were found lateral to the anterior hypothalamus and ventral to the fornix in the area of the lateral hypothalamus. The vasopressin-containing nuclear groups, e.g., paraventricular, supraoptic, suprachiasmatic nuclei, and the nucleus circularis, were devoid of labeled perikarya. Nerve terminals anterogradely labeled with Phaseolus vulgaris-leucoagglutinin were primarily localized to the anterior hypothalamus, in and around the nucleus circularis, and the medial aspect of the supraoptic nucleus. The lateral aspect of the supraoptic nucleus was devoid of nerve terminals as were the paraventricular and suprachiasmatic nuclei. The anatomical connections between the lateral septum and the hypothalamus appear to be necessary for the control of flank marking, since the microinjection of ibotenate into this limbic site significantly reduced odor-induced flank marking as compared to control microinjections of 0.9% NaCl.

This study examines the effects of acid, acid secretagogues, and pepstatin on gastric luminal concentrations of xenopsin-like immunoreactivity (XPLI) by in situ luminal perfusion of the stomach in anesthetized rats. During perfusion with saline over a 2-h period, the concentration of XPLI fell in parallel with acid output. Levels of XPLI fell more rapidly when the saline contained 20 micrograms/ml pepstatin A and when phosphate-buffered saline (pH 7.0) was used. These treatments did not, however, alter acid output. After a basal condition was established at 90 min, intravenous injection of carbachol, pentagastrin, or histamine stimulated acid and pepsin secretion and also led to an increase in XPLI concentration, which was pepstatin sensitive. Acid itself was also a stimulus for pepsin and XPLI output, which were correlated at various levels of acidity. Although pepstatin blocked the effect of acid on XPLI output, it did not lead to an accumulation of xenopsin (XP) precursor in the luminal fluid. However, the decrement in acid-stimulated XPLI output seen in the presence of pepstatin was matched by an increment in XP precursor associated with the mucosal surface. During high-pressure liquid chromatography, approximately 70% of the acid-generated XPLI eluted at the position of mammalian XP. These data support the notion that, during heightened acid output, XP is secreted by a pepsin-dependent process or generated by the action of pepsin on XP precursor present on the mucosal surface of the rat stomach.

Human epidermal keratinocytes reorganize into epidermal inclusion cysts when implanted subcutaneously into athymic mice. During the organization and maturation of these cysts, fibronectin accumulates in the surrounding extracellular matrix and the basement membrane proteins bullous pemphigoid antigen and laminin appear at the epithelial-stromal interface. The sequence in which these proteins appear parallels that seen during reepithelialization of a skin wound in vivo. Fibronectin appears during aggregation of the epidermal cells and persists in the area surrounding the cysts for at least 7 days. Bullous pemphigoid antigen and laminin appear later (by 4 and 7 days, respectively) and ultimately become organized into a continuous band at the periphery of the cyst. This distribution of bullous pemphigoid antigen and laminin at the stromal-epithelial interface persists at least 5 weeks, suggesting that the implanted epidermal cells are capable of developing and maintaining a stable basement membrane zone. Fibronectin, which is abundant in the matrix adjacent to the epidermal cysts and in the surrounding stroma during cyst organization and maturation, diminishes to undetectable levels by 5 weeks. While much of the fibronectin derives from the host tissues, species-specific antibodies to human fibronectin reveal that at least a portion of this protein is synthesized and deposited by the implanted epidermal cells.

Microinjection of arginine vasopressin into the medial preoptic area of the hypothalamus of male and female golden hamsters triggered a complex, stereotypic behavior--flank marking--a type of scent marking used in olfactory communication. The flank marking was not elicited by saline, oxytocin, neurotensin, or angiotensin II. Vasopressin was ineffective when injected into other areas of the hypothalamus or into the lateral cerebroventricle.

Microinjection of neuropeptide Y (NPY) into the suprachiasmatic region of the hypothalamus (SCN) phase shifted the circadian activity rhythm of hamsters housed in constant light. NPY advanced the phase when injected during the 12 h that preceded the daily onset of activity and tended to phase delay the activity cycle when injected during the 12 h after activity onset. In contrast, injection of saline into the SCN or NPY into the ventricular system had no effect on circadian phase. These and other data suggest that NPY functions as a chemical messenger important for the light-dark cycle entrainment of circadian rhythms.

A subpopulation of norepinephrine-containing cells in the cat adrenal medulla contain neurotensin (NT) immunoreactive material. Using high performance liquid chromatography (HPLC) and radioimmunoassay with region-specific antisera we have demonstrated that electrical stimulation of the splanchnic nerve releases NT and its metabolites NT(1-8) and NT(1-12) from cat adrenal gland into the circulation. Blood samples from anesthetized cats were simultaneously collected from the adrenolumbar vein and femoral artery over a 10-min period prior to and during splanchnic nerve stimulation. Trains of stimuli (15 Hz/10V) were applied at 30-s intervals over 10 min. Plasma samples were extracted, run on HPLC and column fractions assayed with C- und N-terminal directed antisera. During splanchnic nerve stimulation unchanged. Concomitant with the increase in NT was a two- to threefold increase in the levels of NT(1-8) and NT(1-12). The chromatographic profiles of extracted adrenal glands showed a major peak of immunoreactive material with the same retention time as NT (18.6 +/- 3.0 pmol/g weight wet of tissue) as well as a small peaks on NT(1-8) (0.96 +/- 0.18 pmol/g) and NT(1-12) (2.05 +/- 0.1 pmol/g). HPLC analysis of a tryptic digest of the NT-like material gave 1.0 equivalent of NT(1-8) and NT(9-13). These results are consistent with the presence of NT in adrenal tissue and its release and metabolism during stimulation of the splanchnic nerve.

To investigate whether the circulating level of neurotensin (NT) in the rat is related to either the 24-h pattern in food consumption or environmental lighting conditions, the plasma level of NT was determined every 4 h in the hepatic-portal vein and the abdominal aorta over the course of 24 h. At each time interval, pooled plasma samples from groups of 4 rats were extracted, lyophilized, reconstituted, and subjected to HPLC. Column fractions were radioimmunoassayed with both N- and C-terminal directed antisera. Animals housed in a 12-h light, 12-h dark cycle and given food and water ad libitum had a significant (P less than 0.05) 24-h variation in the level of chromatographically and immunochemically identified NT in the portal circulation while the level of NT in the systemic circulation remained unchanged. The level of NT in portal blood ranged from 12-38 fmol/ml and was highest in the afternoon, 12-16 h after peak feeding. The level of NT in aortic blood never exceeded 7 fmol/ml. Similar results were obtained from animals exposed to constant illumination for 13-32 h with free access to food and water. The release of NT during the fasting phase of the feeding cycle was dependent upon the prior intake of food, since the level of NT in the hepatic-portal circulation of rats housed in 12-h light, 12-h dark cycle and fasted for 20-24 h was about 2-fold less than that observed in animals allowed free access to food. In summary, these data show that the release and circulation of NT are tightly linked to the circadian pattern of food intake and that the greatest release of NT into the hepatic-portal circulation occurs 5-10 h after the cessation of eating during the fasting phase of the feeding cycle.

Perfusion of the small intestine with a lipid solution results in elevated plasma neurotensin-like immunoreactivity in blood collected from the superior mesenteric vein. Perfusion of amino acids, glucose, hyperosmotic saline, acidified saline, bile salt and diluted rat bile had no effect. Neurotensin-like immunoreactivity in portal plasma was significantly higher than that measured concomitantly in peripheral arterial plasma. Neurotensin, as identified by high pressure liquid chromatography, rose from 4 to 9 fm/ml (n = 4) and 9 to 18 fm/ml (n = 9) extracted plasma during lipid stimulation as compared to the saline control. These results demonstrate that intraintestinal lipid is an effective and specific stimulus for the release of neurotensin from the small intestine into the portal circulation. However, until a target organ can be shown to respond to these modest levels of plasma neurotensin, it is unsettled whether the peptide is a hormone or whether its elevation in plasma is due to "overflow" of a paracrine agent.

The clearance and metabolism of synthetic and tritiated (3H) neurotensin (NT) were studied following its intravenous injection in a pharmacologic dose (500 pmol/kg) into anesthesized rats. Immunoreactive NT (iNT), measured in a radioimmunoassay (RIA) with use of a carboxyl-(C)-terminal directed antiserum, displayed an apparent half-life (t 1/2) of 0.55 min, while that measured by an amino-(N)-terminal directed antiserum had a t 1/2 of 5 min. The radiolabel from injected 3H-NT (3H on Tyr3,11) had a t 1/2 of 6.5 min. High-pressure liquid chromatography of extracts of plasma obtained from the circulation 0.5-3 min after injection of NT and 3H-NT showed the presence of NT and the generation mainly of the fragments NT1-8, NT1-11, and NT9-13, as well as free 3H-labeled tyrosine. The apparent half-lives of intravenously injected synthetic NT1-8, NT1-11 and NT1-12 measured with the N-terminal RIA were 9, 5 and 5 min, respectively, while that for NT9-13 was less than 0.5 min. These results indicate that exogenously injected NT is rapidly metabolized to form N-terminal fragments which are cleared more slowly than NT. These findings suggest that use of N-terminal antisera to detect the release of endogenous NT into the circulation is likely to yield measurements of the fragments NT1-8 and NT1-11 which thus far have been found to be biologically inactive.

The present studies were undertaken to determine whether a 24 h rhythm occurs in neurotensin (NT) levels in the small intestine of the rat and if so, whether the rhythm depends upon the 24 h cycles of light or feeding. A total of 145 male rats were sacrificed at 4 h intervals and the levels of neurotensin-like immunoreactivity (NTLI) in the middle 30 cm of small intestine were determined by radioimmunoassay with region specific antisera. There was a significant (P less than 0.05) 24 h rhythm in the levels of NTLI in groups of rats maintained under constant illumination or a 12:12 light:dark cycle and fasted for either 24 h or provided food ad libitum. Levels of NTLI ranged from 50 to 140 pm/g and were highest during the early morning (0400-0800 h) and lowest during the afternoon (1200-1600 h). The NTLI from samples taken at 0400 and 1600 h was subjected to high-performance liquid chromatography. The levels of chromatographically and immunochemically characterized NT were consistent with the levels of NTLI, evidence that the 24 h variation in NTLI most likely reflects changes in the intestinal content of NT and not other substances with similar immunochemical properties.

Extracts of goldfish retina and brain were analysed by high-pressure liquid chromatography and radioimmunoassays for neurotensin (NT), substance P (SP) and related peptides. Two major peaks of immunoreactive NT were observed, both more hydrophilic than mammalian NT. Although these two forms reacted equally well with two antisera towards the biologically active carboxyl terminal region of NT, they were not recognized by an amino terminal antiserum, nor by antisera toward the related peptides, LANT-6 and xenopsin. Retinal immunoreactive SP eluted as one major peak which may represent the teleost equivalent of mammalian SP; region-specific antisera indicated phylogenetic conservation of the carboxyl terminal region. A more hydrophilic immunoreactive form was found only in brain, and two more hydrophobic forms found in both tissues were relatively more abundant in retina than in brain. The concentrations and molecular forms of these peptides were unchanged after either 48 hr of light adaptation or 48 hr of dark adaptation.

Arginine-vasopressin (AVP) microinjected into the medial preoptic area (MPOA) induces flank marking behavior, a form of olfactory communication, in the golden hamster. When exposed to the odors of conspecifics flank marking behavior occurs naturally in association with grooming of the flank gland region. The present study examined whether microinjection of AVP, oxytocin (OXY) and other biologically active peptides into the medial preoptic area (MPOA), lateral cerebroventricle (LV) or the ventromedial or lateral hypothalamus (VMH-LH) would elicit flank gland grooming. Microinjection of AVP and OXY produced 2-3 times more flank gland grooming when microinjected into the MPOA than saline, neurotensin or angiotensin II. Injection of AVP into the LV and VMH-LH produced significantly less flank gland grooming than when injected into the MPOA.

Although the anterior hypothalamus has been implicated in the control of aggression in various rodent species, little is known about the neurochemical mechanisms mediating this control. It has been established that flank marking, which occurs with high frequency during agonistic encounters in hamsters, is dependent upon vasopressin-sensitive neurons in the anterior hypothalamus. The present study was undertaken to determine whether intraspecific aggression in this species is similarly influenced by vasopressin in this area of the hypothalamus. Adult male hamsters, surgically implanted with guide cannulae aimed at the anterior hypothalamus, were microinjected with three different concentrations of the V1-receptor antagonist d(CH2)5Tyr(Me)AVP or a vehicle control of 0.9% NaCl. Sixty minutes after each microinjection a smaller male hamster was introduced into the home cage of the treated hamster. The resident hamsters showed a significant dose-dependent reduction in the number of biting attacks on the intruders over the 10 minute test period. The V1-receptor antagonist also caused a significant increase in the resident hamster's latencies to attack the intruder. However, the resident hamsters' total contact time with the intruder was unaffected by drug treatment suggesting that the reduction of aggression was not due to a generalized effect upon social behavior. The specificity of the drug treatment was further supported by the observation that it did not affect resident hamsters' sexual motivation or ability to mount a receptive female. These data suggest that vasopressin-sensitive neurons in the anterior hypothalamus are involved in the control of intraspecific aggression in male hamsters.

A new biologically active peptide of the neurotensin (NT) family, shown previously to cross-react in a COOH-terminal-directed radioimmunoassay for bovine NT, has been isolated from extracts of chicken intestine and identified as H-Lys-Asn-Pro-Tyr-Ile-Leu-OH, which is identical with the biologically active COOH-terminal half of NT except for the amino acid substitutions Lys/Arg and Asn/Arg. It is proposed that this peptide be referred to as Lys8, Asn9, NT8-13 (LANT-6). Synthetic material prepared with this amino acid sequence using the Merrifield technique was immunochemically, chromatographically, and biologically indistinguishable from the native peptide. In contrast to chicken NT which induced hypotension, hyperglycemia, increased vascular permeability, and cyanosis when injected intravenously into anesthetized rats, synthetic LANT-6 brought about primarily a hypertensive response and had little ability to promote hyperglycemia, increased vascular permeability, and cyanosis. In rats pretreated with the alpha-blocker phentolamine and in adrenalectomized rats, the hypertensive response to LANT-6 was blocked, suggesting that adrenal catecholamines mediated this effect. These findings suggest that LANT-6, a natural variant of NT with a different spectrum of biologic activity, may be a NT-related messenger peptide with a different function(s).

The suprachiasmatic nucleus has been identified tentatively as a circadian pacemaker. To examine the functional role of peptides found within suprachiasmatic neurons, avian pancreatic polypeptide and vasopressin were microinjected into the suprachiasmatic region. Avian pancreatic polypeptide, but not vasopressin, shifted the phase of the wheelrunning rhythm as a function of the time of its injection within the circadian cycle. Avian pancreatic polypeptide or a similar peptide may be one component of the neurochemical processes underlying entrainment to the light-dark cycle.

This paper will review some of the present information on the biology of basal cell carcinoma. Recent developments include a better understanding of the basement membrane components surrounding the tumor nodules, as well as identifying the most actively dividing cells in solid basal cell carcinoma by autoradiographic techniques. The implications of a recently developed animal model will also be discussed.

The medial preoptic-anterior hypothalamus (MPOA-AH) is necessary for expression of several testosterone-dependent behaviors including a form of hamster scent marking, called flank marking. Since arginine vasopressin (AVP) plays a critical role in the control of flank marking by the MPOA-AH the present study examined whether testosterone can influence the amount of flank marking produced by AVP microinjected into the MPOA-AH. The dose-dependent induction of flank marking by AVP was found to be reduced by approximately 50% in castrated male hamsters when compared to intact or testosterone-treated castrates. These data demonstrate that testosterone influences the amount of flank marking produced by AVP within the MPOA-AH.

Since it is thought that flank marking communicates dominance status, experiments were designed to look at changes in aggression and flank marking behaviors in pairs of male hamsters with intact flank glands (Experiment One) or when one (Experiment Two) or both (Experiment Three) members of a pair had their flank glands surgically removed. In Experiment One the dominant members of twelve pairs of hamsters had a mean daily frequency of flank marks that was over two-fold greater than their subordinate partners, F(1,11) = 17.59, p less than 0.001. Over the course of five consecutive daily tests there was a significant decrease in the aggression index of both the dominant, t(44) = 4.49, p less than 0.01, and subordinate, t(44) = 3.33, p less than 0.01, hamsters. Accompanying the decrease in aggression was a significant increase in the flank marking of both dominant, t(44) = 7.8, p less than 0.01, and subordinate, t(44) = 3.59, p less than 0.01, hamsters. In Experiment Two, six out of eleven flank glandectomized hamsters were dominant over their sham operated partners while the remaining five were subordinate. Unlike Experiment One there was no significant difference in the flank marking between dominant and subordinate hamsters, in fact, in seven pairs the subordinate hamsters flank marked more than their dominant partners. In Experiment Three both hamsters had their flank glands removed, and as in Experiment Two, there was no significant difference in flank marking between dominant and subordinate hamsters, neither was there any significant change in their aggression and flank marking behaviors over the course of the five test periods.(ABSTRACT TRUNCATED AT 250 WORDS)

Neurons immunoreactive to luteinizing hormone-releasing hormone (LHRH) are localized to the medial preoptico-septal region of the rat hypothalamus, an area known to be essential for the regulation of the surge of luteinizing hormone (LH) that precedes ovulation. The effect of neurotensin (NT) on circulating LH levels following its discrete microinjection into this region was evaluated. Within 30 min after the stereotaxic microinjection of 40 ng of NT in 50 nl into the medial preoptic area (MPOA) just rostral to the organum vasculosum of the lamina terminalis in ovariectomized (OVX), anesthetized rats, plasma LH levels rose from 417 +/- 36 to 923 +/- 113 ng/ml (p less than 0.001). There was also a significant increase (p less than 0.001) in plasma LH levels following the microinjection of 50 ng of norepinephrine in 50 nl in this same site. Similarly, levels of LH increased from 48 +/- 7 to 110 +/- 19 ng/ml (p less than 0.004) following the microinjection of NT into the rostral MPOA on the morning of proestrus in anesthetized rats. In contrast, saline, substance P, leu-enkephalin and LHRH microinjected in the rostral MPOA of OVX rats had no significant effect on circulating levels of LH. The microinjection of NT 0.4 mm rostral or caudal to this area was also without effect. The presence of two binding sites with KdS of 4.2 and 29 nM and site concentrations of 0.11 and 0.68 pmol/mg in tissue homogenates of the rostral MPOA were also established. These data suggest a role for NT in the central regulation of LH release.

Dopaminergic neurons arising from cell bodies in the rostral arcuate nucleus of the hypothalamus have been shown to make axoaxonic contact with neurohypophyseal neurosecretory axons. In this study, electrical stimulation of the rostral arcuate nucleus depresses multiunit electrical activity recorded from neurosecretory axons within the neurohypophysis. After a single 5-s stimulus train, neurohypophyseal electrical activity is reduced to 6% of control. The superfusion of dopamine (5 micrograms/microliters) onto the neurohypophysis also has an inhibitory effect. Superfusion directly onto the neurohypophysis of the dopamine-receptor antagonist, pimozide (1 micrograms/microliters), abolishes the inhibitory effect of arcuate nucleus stimulation. These findings suggest that the dopaminergic innervation of the neurohypophysis may have an inhibitory influence on the release of neurohypophyseal hormones.

Flank marking, a form of olfactory communication displayed by hamsters, is dependent upon vasopressin-sensitive neurons in the anterior hypothalamus. In the present study two vasopressin type-1 (V1) receptor antagonists, d(CH2)5Tyr(Me)AVP and dPTyr(Me)AVP were tested for their ability to block flank marking stimulated by the microinjection of arginine vasopressin (AVP) into the anterior hypothalamus. Dose-response curves were established for AVP and flank marking in the presence or absence of different concentrations of each antagonist. DPTyr(Me)AVP was microinjected into the anterior hypothalamus 1 h before the microinjection of AVP while d(CH2)5Tyr(Me)AVP and AVP were prepared together and delivered as a single microinjection. This procedure was necessary because dPTyr(Me)AVP, but not d(CH2)5Tyr(Me)AVP, had agonist activity when initially injected into the anterior hypothalamus in concentrations ranging from 0.90-900 microM. The ED50 values (microM) for dPTyr(Me)AVP and AVP were 17.9 and 0.90, respectively. The initial agonist activity of dPTyr(Me)AVP was always followed by blocker activity. Both V1-receptor antagonists caused a dose-dependent decrease in AVP-stimulated flank marking. Maximal inhibition of AVP-stimulated flank marking was produced with approximately 1.0 mM of either antagonist. Both antagonists blocked AVP-stimulated flank marking behavior for over 12 h following their microinjection.

The levels of neurotensin (NT) and its metabolite, the N-terminal octapeptide (NT1-8), identified by HPLC and measured by RIA, were increased in the hepatic-portal circulation of the anesthetized rat during perfusion of the small intestine with a lipid solution, while levels of both peptides remained unchanged in the general circulation. There was no significant arteriovenous difference for NT or NT1-8 during saline perfusion of the small intestine. Plasma collected from the superior mesenteric vein during the infusion of [3H]NT into the superior mesenteric artery showed major peaks of radioactivity with the retention times of NT1-8 and NT1-11 on HPLC. Only 12% of the radioactivity recovered from plasma was intact NT. These studies demonstrate that chromatographically identified NT and its metabolite, NT1-8, are elevated in the portal circulation but not systemic circulation during lipid perfusion and that the small intestine may be both the site of release and metabolism of NT.

The purpose of this study was to define the vasopressin-sensitive area in the anterior hypothalamus-medial preoptic area (AH-MPOA) of the golden hamster that is involved in the expression of flank-marking behavior. Male hamsters implanted with guide cannulae stereotaxically aimed at various sites in the AH-MPOA were microinjected initially with 0.1 ng of arginine vasopressin (AVP) in a volume of 10 nl. Hamsters that flank-marked in response to these injections were subsequently microinjected into the same sites with kainic acid (0.2 microgram/20 nl; n = 10) or an equal volume of 1 M NaOH as a vehicle control (n = 10). Four days later hamsters were tested for odor-induced flank marking by placing them into the recently vacated home cage of other hamsters and for flank marking in response to the microinjection of AVP. Animals treated with kainic acid exhibited significantly (p less than 0.01) fewer AVP and odor-induced flank marks as compared to the number of flank marks observed prior to treatment. There was no significant reduction in the number of flank marks in hamsters microinjected with the NaOH vehicle. In another group of hamsters, microinjection of kainic acid (0.2 microgram/20 nl) into the 3rd ventricle (n = 4) and other sites of the hypothalamus (n = 4) did not significantly alter odor-induced flank marking. The locations of the microinjection sites indicate that the neurons sensitive to AVP and involved in the expression of flank-marking behavior are found in the ventromedial area of the AH-MPOA extending from the caudal border of the suprachiasmatic nucleus to the rostral limit of the supraoptic nucleus.(ABSTRACT TRUNCATED AT 250 WORDS)

We have previously reported that neurotensin (NT) is released from the small intestine and elevated in the hepatic-portal circulation in response to the perfusion of the small intestine with a micellar solution of oleic acid. In order to determine the minimum acyl chain length and whether the presence of a carboxylic acid is necessary for the stimulation of NT release, the small intestine of anesthetized rats was perfused with test solutions of fatty acids of 2-, 4-, 8-, or 18-carbons or fatty alcohols of 2-, 4-, or 8-carbons at a concentration of 1 mM prepared in 2.4 mM taurodeoxycholate in 0.9% NaCl. Blood samples, collected from the superior mesenteric vein immediately before the start of the test perfusion and at 15-min intervals thereafter, were extracted immediately and radioimmunoassayed for NT-like immunoreactivity (NTLI) with a C-terminal-directed antiserum. Perfusions of fatty acids with 4 or more carbons and alcohols of 2 or more carbons resulted in a significant elevation (P less than 0.05) in plasma levels of NTLI above the values obtained before the onset of perfusion. Perfusions with ethanol resulted in a value of 4.3 +/- 0.03 mg/dl (SEM) in blood from the superior mesenteric vein while there was no increase in ethanol levels in the peripheral circulation. Perfusion with taurodeoxycholate and 0.9% NaCl alone had no significant effect on plasma levels of the NTLI. In order to characterize the chemical nature of the elevated NTLI, plasma samples from animals perfused with test solution were collected, extracted, pooled, and subjected to HPLC. NT and its N-terminal metabolite, NT(1-8), were quantitated. NT was defined as material having the same retention time as synthetic NT standard and having comparable measurements using N- and C-terminal-directed antisera. Perfusions of fatty acids of four or more carbons and alcohols of two or more carbons resulted in a 2- to 4-fold increase of both NT and NT(1-8) levels in plasma. It is particularly interesting that perfusion with ethanol (2-carbons) causes an elevation in plasma NT, because perfusion with acetic acid (2-carbons) does not increase NTLI. The fact that perfusion of ethanol is effective in releasing intestinal NT suggests that NT may mediate some of the biological effects observed after the consumption of alcohol.

The present study examined whether the induction of scent marking behavior and grooming of the flank gland region by injection of arginine-vasopressin (AVP) or oxytocin (OXY) into the anterior hypothalamus-medial preoptic area (AH-MPOA) required the presence of the flank glands. The flank glands were surgically removed (GLDX) in ten hamsters or patches of skin just dorsal to the flank glands were removed (SHAM) in the control group (N = 7). No statistically significant differences were observed in flank marking or flank grooming between the GLDX and SHAM groups during a 10 min test period immediately following injection of AVP or OXY. AVP and OXY injection produced similar amounts of flank grooming, but AVP resulted in significantly (p less than 0.01) more flank marking than OXY. These data indicate that scent marking induced by AVP injected into the AH-MPOA is similar to environmentally induced scent marking in not requiring the presence of an intact scent gland.

Basal cell carcinomas (BCCs) obtained from 22 subjects undergoing microscopically controlled surgery were transplanted to 40 athymic (nude) mice. With no further immunosuppression of the mice, no tumor growth was noted in the first 14 attempts. When mice were further immunosuppressed with anti-lymphocyte serum (ALS) injections and by splenectomy, successful tumor growth was achieved in 15 of 22 mice by a subcutaneous implantation technique and in 1 of 4 by a superficial grafting technique. Transplanted BCC retained the morphology and basement membrane proteins typical of human BCC. As determined by autoradiography, 3H-thymidine was incorporated primarily in the peripheral palisaded cells of the transplanted tumor. Successful use of the athymic mouse model for study of human BCC requires use of mice further immunosuppressed by splenectomy and ALS, and the use of a subcutaneous implantation technique. With the use of this model, studies of the biology of human BCC may be possible.

Treatment of mammalian plasmas or sera with pepsin gave rise to extraordinary quantities (1-5 microM) of immunoreactive neurotensin (NT)-related peptide(s). Although immunochemical and chromatographic analyses indicated that the peptides liberated by pepsin differed from authentic neurotensin, one of the major immunoreactive products displayed NT-like biological properties. Partially purified preparations of the immunoreactive peptides increased cutaneous vascular permeability when injected intradermally in rats and released histamine from isolated rat mast cells. The pepsin-generated peptides appeared to share the biologically active C-terminal portion of NT, since they reacted with antisera selective for this region but were not recognized by N-terminal-directed antisera. Gel permeation chromatography demonstrated the presence of two substrates in plasma which liberated iNT upon treatment with pepsin, one in the albumin fraction (mol wt, 65 K) and the other a globulin (mol wt, 350 K). A variety of other proteases and substrates failed to have this effect. These results suggest the existence of a system(s) in blood, analogous to the renin-angiotensin system, for the generation of biologically active NT-related peptides.