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Rubio-Navarro L, Torrero C, Regalado M, Salas M. Analysis of the Sensory and Hedonic Impacts of Sweet and Bitter Tastes in Perinatally Underfed Rats. ACTA ACUST UNITED AC 2014. [DOI: 10.4236/jbbs.2014.49041] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Suwabe T, Mistretta CM, Krull C, Bradley RM. Pre- and postnatal differences in membrane, action potential, and ion channel properties of rostral nucleus of the solitary tract neurons. J Neurophysiol 2011; 106:2709-19. [PMID: 21865434 DOI: 10.1152/jn.00178.2011] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
There is little known about the prenatal development of the rostral nucleus of the solitary tract (rNST) neurons in rodents or the factors that influence circuit formation. With morphological and electrophysiological techniques in vitro, we investigated differences in the biophysical properties of rNST neurons in pre- and postnatal rats from embryonic day 14 (E14) through postnatal day 20. Developmental changes in passive membrane and action potential (AP) properties and the emergence and maturation of ion channels important in neuron function were characterized. Morphological maturation of rNST neurons parallels changes in passive membrane properties. Mean soma size, dendritic branch points, neurite endings, and neurite length all increase prenatally. whereas neuron resting membrane potential, input resistance, and time constant decrease. Dendritic spines, on the other hand, develop after birth. AP discharge patterns alter in pre- and postnatal stages. At E14, neurons generated a single TTX-sensitive, voltage-gated Na(+) AP when depolarized; a higher discharge rate appeared at older stages. AP amplitude, half-width, and rise and fall times all change during development. Responses to current injection revealed a number of voltage-gated conductances in embryonic rNST, including a hyperpolarization-activated inward current and a low-threshold Ca(2+) current that initiated Ca(2+) spikes. A hyperpolarization-activated, transient outward potassium current was also present in the developing neurons. Although the properties of these channels change during development, they are present before synapses form and therefore, can contribute to initial establishment of neural circuits, as well as to the changing electrophysiological properties in developing rNST neurons.
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Affiliation(s)
- Takeshi Suwabe
- Dept. of Biologic and Materials Sciences, School of Dentistry, Univ. of Michigan, Ann Arbor, MI 48109-1078, USA
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Méndez-Gallardo V, Robinson SR. Opioid mediation of amniotic fluid effects on chemosensory responsiveness in the neonatal rat. Dev Psychobiol 2011; 52:740-54. [PMID: 21117244 DOI: 10.1002/dev.20469] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The present study investigated if oral exposure to milk or amniotic fluid (AF) alters responsiveness to sensory stimulation in the neonatal rat, and whether these effects are mediated by the opioid system. Facial wiping evoked by intraoral lemon infusion was used as a measure of sensory responsiveness. Pups were tested in a supine posture, because they showed more paw-face strokes during facial wiping than pups tested prone (Experiment 1). Moreover, pups orally exposed to milk (Experiment 2) or AF (Experiment 3) showed a diminished wiping response to lemon compared to controls exposed to water. Blockade of opioid receptors with the nonselective antagonist naltrexone (Experiment 4) or the kappa antagonist nor-binaltorphimine (Experiment 5) reinstated higher levels of facial wiping after AF exposure. These findings confirm developmental continuity between fetal and neonatal behavioral responses to AF and the ability of AF to induce activity at kappa receptors of the endogenous opioid system.
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Haino T, Hironaka S, Ooka T, Tokita K, Kubota Y, Boughter JD, Inoue T, Mukai Y. Orosensory deprivation alters taste-elicited c-Fos expression in the parabrachial nucleus of neonatal rats. Neurosci Res 2010; 67:228-35. [PMID: 20302893 DOI: 10.1016/j.neures.2010.03.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2009] [Revised: 03/10/2010] [Accepted: 03/11/2010] [Indexed: 10/19/2022]
Abstract
In the present study we examined the effects of neonatal orosensory deprivation on taste-elicited gustatory activity in the rat parabrachial nucleus (PBN) using the functional anatomical marker c-Fos. Animals in three groups (GG, GO and GM) received gastric cannula implantation surgery on postnatal day 9 (P9). Animals in the fourth group (MR) did not receive any surgery. GG rats were fed by infusion of artificial milk directly into the stomach. GO rats were fed by intraoral infusion of artificial milk. GM and MR rats were reared by their mother with free access to mother's milk, water and rat chow. Rats from all groups were similar in body weight and length by P21. On P21 rats in all groups were intraorally presented with 0.5M sucrose solution and the brains were extracted and processed for c-Fos immunohistochemistry. Taste-elicited c-Fos expression in both the gustatory waist area, and the external lateral subnucleus of the PBN in rats in the GG group was significantly more robust than in the other three groups. These findings suggest a substantial alteration in orosensory-evoked neuronal response in this nucleus, due to sensory or motor deprivation during a critical developmental stage.
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Affiliation(s)
- Toshiyuki Haino
- Department of Hygiene and Oral Health, Showa University School of Dentistry, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8555, Japan
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Kozlov AP, Nizhnikov ME, Varlinskaya EI, Spear NE. Pharmacological effects of ethanol on ingestive behavior of the preweanling rat. Behav Brain Res 2009; 205:162-74. [PMID: 19549546 PMCID: PMC2753683 DOI: 10.1016/j.bbr.2009.06.023] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2009] [Revised: 06/09/2009] [Accepted: 06/15/2009] [Indexed: 01/03/2023]
Abstract
The present study was designed to test the hypothesis that sensitivity of ingestive behavior of infant rat to the pharmacological effects of ethanol changes between postnatal (P) days 9 and 12. The intake of 0.1% saccharin and water, general motor activity, and myoclonic twitching activity were assessed following administration of three doses of ethanol (0, 0.25, and 0.5 g/kg) while fluids were free available to the animals. The 0.5 g/kg dose of ethanol attenuated saccharin intake in P9 pups and enhanced saccharin intake in P12 rats. On P12 some sex-related differences emerged at 0.5 g/kg of ethanol, with saccharin intake being higher in females than in their male counterparts. Taste reactivity probe revealed that 0.5 g/kg of ethanol increased taste responsiveness to saccharin on P12 but only to infusions presented at a high rate. The results of the present study indicate that ontogenetic changes in sensitivity to the effects of ethanol on ingestive behavior occur during the second postnatal week, with P9 animals being more sensitive to the inhibitory (sedative) effects on saccharin intake and P12 rats being more sensitive to the stimulatory effects of ethanol. We suggest that acute ethanol enhanced saccharin intake via sensitization of oral response to appetitive taste stimulation.
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Affiliation(s)
- Andrey P Kozlov
- Center for Development & Behavioral Neuroscience, Department of Psychology, Binghamton University, Binghamton, NY 13902-6000, United States
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6
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Kozlov AP, Varlinskaya EI, Spear NE. Ethanol, saccharin, and quinine: early ontogeny of taste responsiveness and intake. Alcohol Clin Exp Res 2007; 32:294-305. [PMID: 18162068 DOI: 10.1111/j.1530-0277.2007.00581.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Rat pups demonstrate high levels of immediate acceptance of ethanol during the first 2 weeks of postnatal life. Given that the taste of ethanol is most likely perceived by infant rats as a combination of sweet and bitter, high intake of ethanol early in ontogeny may be associated with age-related enhanced responsiveness to the sweet component of ethanol taste, as well as with ontogenetic decreases in sensitivity to its bitter component. Therefore, the present study compared responsiveness to ethanol and solutions with bitter (quinine) and sweet (saccharin) taste in terms of intake and palatability across the first 2 weeks of postnatal life. METHODS Characteristic patterns of responsiveness to 10% (v/v) ethanol, 0.1% saccharin, 0.2% quinine, and water in terms of taste reactivity and fluid intake were assessed in rat pups tested on postnatal day (P) 4, 9, or 12 using a new technique of on-line monitoring of fluid flow through a two-channel intraoral cannula. Taste reactivity included analysis of ingestive and aversive responses following six intraoral infusions of the test fluids. This taste reactivity probe was followed by the intake test, in which animals were allowed to voluntarily ingest fluids from an intraoral cannula. RESULTS Pups of all ages showed more appetitive responses to saccharin and ethanol than to water or quinine. No age-related differences were apparent in taste responsiveness to saccharin and ethanol. However, the age-related pattern of ethanol intake drastically differed from that of saccharin. Intake of saccharin increased from P4 to P9 and decreased substantially by P12, whereas intake of ethanol gradually increased from P4 to P12. Intake of ethanol was significantly lower than intake of saccharin on P9, whereas P12 pups took in more ethanol than saccharin. CONCLUSION The findings of the present study indicate ontogenetic dissociations between taste reactivity to ethanol and saccharin and intake of these solutions, and suggest that high acceptance of ethanol early in ontogeny may not be associated with its orosensory properties but rather with the pharmacological effects of ethanol.
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Affiliation(s)
- Andrey P Kozlov
- Center for Developmental Psychobiology, Department of Psychology, Binghamton University, Binghamton, New York 13902-6000, USA
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Abstract
Review of the ontogeny of the controls of independent ingestion reveals that some of the direct and indirect controls of meal size identified in adult rats function in the first three postnatal weeks. The controls appear sequentially and some of them change their potency after they emerge. Indirect controls exerted by metabolism and adiposity do not emerge until the fourth postnatal week or later in the postweaning period. Recent experiments in rats with monogenic obesities involving the leptin and cholecystokinin receptors have demonstrated the usefulness of independent ingestion in the detection of the earliest expression of hyperphagia. Although much remains to be learned about the normal controls of independent ingestion, it is clear that it provides relevant information about the development of normal and abnormal controls of meal size in rodents that is useful for translational research into the controls of meal size in normal and obese children.
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Affiliation(s)
- Gerard P Smith
- Department of Psychiatry, Weill Medical College of Cornell University, Presbyterian Hospital, 21 Bloomingdale Road, White Plains, New York, New York 10605, USA.
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Kozlov AP, Petrov ES, Varlinskaya EI, Spear NE. Taste differentiation in the context of suckling and independent, adultlike ingestive behavior. Dev Psychobiol 2006; 48:133-45. [PMID: 16489597 DOI: 10.1002/dev.20123] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The present study compared intake of sweet (saccharin), bitter (quinine), and neutral (water) tastants available either in the context of suckling behavior through a surrogate nipple or independent adultlike feeding through an intraoral cheek cannula in 3-hr-old newborn rats lacking any suckling experience and 24-hr-old rats with regular experience with the dam's nipple. The new technique of online monitoring of fluid flow was applied for assessment of the temporal patterns of ingestion. Newborn and 1-day-old rats tested in the context of suckling behavior showed extremely low intake of quinine, moderate intake of water, and high intake of saccharin. In the same way, they demonstrated low intake of quinine and high intake of saccharin in the context of independent feeding, but intake of water was also high and comparable to that of saccharin. Suckling rats attained higher efficacy of fluid extraction from nipple than pups drinking from cannula. The differential responsiveness to quinine, saccharin, and water in suckling rats was also manifested through attachment behavior, with pups spending less time on the nipple providing quinine and more time on the nipple with saccharin than on the nipple providing water. These results suggest that neonates show taste differentiation as early as 3 hr after birth, and that this taste differentiation is more pronounced in the context of suckling behavior than in the context of adultlike, independent ingestion.
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Affiliation(s)
- Andrey P Kozlov
- Department of Psychology, Center for Developmental Psychobiology, Binghamton University-SUNY, Binghamton, New York, USA
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Truxell E, Spear NE. Immediate acceptance of ethanol in infant rats: ontogenetic differences with moderate but not high ethanol concentration. Alcohol Clin Exp Res 2005; 28:1200-11. [PMID: 15318119 DOI: 10.1097/01.alc.0000134220.34842.18] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND During the preweanling period, infant rats consume large quantities of ethanol without initiating procedures. Ethanol intake during this period has seemed to be age related, with peak consumption occurring near the end of the second postnatal week, on postnatal day (P)12, but only a narrow range of conditions has been tested. METHODS Independent ingestion of ethanol was measured at each of two ages, P12 and P18, with systematic variation in ethanol concentration, duration of exposure, and mode of fluid presentation. Ethanol ingestion was measured in terms of percentage body weight gain, grams of absolute ethanol ingested per unit body weight, and blood ethanol concentration. RESULTS Ingestion of 30% ethanol during a 40-min period led to blood ethanol concentrations approaching 300 mg/100 ml at both P12 and P18. For ethanol concentrations of 10 or 20%, ingestion at P12 was greater than at P18. When ethanol was available from ethanol-soaked Kimwipe on the floor, ethanol intake transdermally or by inhalation was apparent but accounted for less than half of the overall ethanol intake. It was clear that for older infants, which are susceptible to ethanol's diuretic effects and are much more likely to self-void than those at P12, measurement of intake by percentage body weight gain can underestimate ethanol ingestion. CONCLUSIONS The infant rat ingests extraordinarily high levels of ethanol, in concentrations as high as 30%, without initiation procedures. Acceptance of ethanol by infants on first exposure contrasts with the conventional rejection of these concentrations by adults. It is unclear why younger infants (P12) consume more 10 and 20% ethanol than older (P18) infants. These and other differences in ethanol intake between infants and older animals may be due initially to the relative ontogeny of receptors for bitter and sweet taste and subsequently to other factors.
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Affiliation(s)
- Eric Truxell
- Department of Psychology, Binghamton University, Binghamton, New York 13902-6000, USA
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Petrov ES, Nizhnikov ME, Kozlov AP, Varlinskaya EI, Kramskaya TA, Spear NE. Repetitive exposures to a surrogate nipple providing nutritive and non-nutritive fluids: effects on suckling behavior of the newborn rat. Appetite 2004; 43:185-94. [PMID: 15458805 DOI: 10.1016/j.appet.2004.04.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2003] [Revised: 02/10/2004] [Accepted: 04/21/2004] [Indexed: 11/24/2022]
Abstract
Responsiveness to a surrogate nipple providing water, 0.1% saccharin, 10% sucrose, pedialyte, or milk was tested in naïve-to-suckling newborn rats during six 10-min exposures, one every 1.5 h over a 7.5 h period. Across a succession of exposures, newborn rats repeatedly attached to and ingested milk from a surrogate nipple, yielding significant body weight gain and increased concentration of blood plasma glucose. Initially, pups ingested considerable amounts of saccharin and sucrose, but then dramatically decreased their consumption of these fluids across the experimental sessions. Intake of milk was significantly higher than that of all other substances. Blood glucose concentration in pups treated with water, saccharin, sucrose, and pedialyte did not differ significantly from that of non-treated pups. The present data suggest a potential contribution of a fluid's palatability and nutritive value in the persistence and efficacy of diet intake for neonatal rats in the context of suckling behavior.
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Affiliation(s)
- Evgeniy S Petrov
- Department of Psychology, Center for Developmental Psychobiology, Binghamton University-SUNY, Box 6000, Binghamton, NY 13902-6000, USA
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Brumley MR, Robinson SR. Facial wiping in the rat fetus: variation of chemosensory stimulus parameters. Dev Psychobiol 2004; 44:219-29. [PMID: 15103732 DOI: 10.1002/dev.20005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Fetal rats reliably express a facial wiping response to novel chemosensory stimuli. Previous research has examined facial wiping as an early form of motor coordination and as a behavioral indicator of sensory responsiveness. The present study examined how variation in stimulus parameters of lemon odor infusion (concentration, volume, and infusion time) affected the wiping response of E20 rat fetuses. Infusions of higher concentration or greater volume generally elicited wiping responses of greater duration and more strokes. Most facial wipes involved strokes by single forelimbs; however, bilaterally synchronous wiping was expressed only in bouts of at least seven wipes, and was facilitated by stimuli of moderate intensity. These findings suggest that the total number of wiping strokes or bout duration are well suited as measures of overall sensory responsiveness in the fetus and that chemosensory stimulus parameters exert a permissive influence on interlimb coordination during a bout of facial wiping.
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Affiliation(s)
- Michele R Brumley
- Laboratory of Comparative Ethogenesis, Department of Psychology, University of Iowa, Iowa City, IA 52242, USA
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Grabauskas G, Bradley RM. Postnatal development of inhibitory synaptic transmission in the rostral nucleus of the solitary tract. J Neurophysiol 2001; 85:2203-12. [PMID: 11353035 DOI: 10.1152/jn.2001.85.5.2203] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To explore the postnatal development of inhibitory synaptic activity in the rostral (gustatory) nucleus of the solitary tract (rNST), whole cell and gramicidin perforated patch-clamp recordings were made in five age groups of rats [postnatal day 0-7 (P0-7), P8-14, P15-21, P22-30, and P >55]. The passive membrane properties of the developing rNST neurons as well as the electrophysiological and pharmacological characteristics of single and tetanic stimulus-evoked inhibitory postsynaptic potentials (IPSPs) were studied in brain slices under glutamate receptor blockade. During the first postnatal weeks, significant changes in resting membrane potential, spontaneous activity, input resistance, and neuron membrane time constant of the rNST neurons occurred. Although all the IPSPs recorded were hyperpolarizing, the rise and decay time constants of the single stimulus shock-evoked IPSPs decreased, and the inhibition response-concentration function to the gamma-aminobutyric acid (GABA) receptor antagonist bicuculline methiodide (BMI) shifted to the left during development. In P0-7 and P8-14, but not in older animals, the IPSPs had a BMI-insensitive component that was sensitive to block by picrotoxin, suggesting a transient expression of GABA(C) receptors. Tetanic stimulation resulted in both short- and long-term changes of inhibitory synaptic transmission in the rNST. For P0-7 and P8-14 animals tetanic stimulation resulted in a sustained hyperpolarization that was maintained for some time after termination of the tetanic stimulation. In contrast, tetanic stimulation of neurons in P15-21 and older animals resulted in hyperpolarization that was not sustained but decayed back to a more positive level with an exponential time course. Tetanic stimulation resulted in potentiation of single stimulus shock-evoked IPSPs in ~50% of neurons in all age groups. These developmental changes in inhibitory synaptic transmission in the rNST may play an important role in shaping synaptic activity in early development of the rat gustatory system during a time of maturation of taste preferences and aversions.
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Affiliation(s)
- G Grabauskas
- Department of Biologic and Materials Sciences, School of Dentistry, University of Michigan, Ann Arbor, Michigan 48109, USA
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Cheslock SJ, Varlinskaya EI, Petrov ES, Silveri MM, Spear LP, Spear NE. Ethanol as a Reinforcer in the Newborn's First Suckling Experience. Alcohol Clin Exp Res 2001. [DOI: 10.1111/j.1530-0277.2001.tb02226.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Petrov ES, Varlinskaya EI, Spear NE. Self-administration of ethanol and saccharin in newborn rats: Effects on suckling plasticity. Behav Neurosci 2001. [DOI: 10.1037/0735-7044.115.6.1318] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Hunt PS, Lant GM, Carroll CA. Enhanced intake of ethanol in preweanling rats following interactions with intoxicated siblings. Dev Psychobiol 2000. [DOI: 10.1002/1098-2302(200009)37:2<90::aid-dev4>3.0.co;2-d] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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17
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Lasiter PS. Effects of orochemical stimulation on postnatal development of gustatory recipient zones within the nucleus of the solitary tract. Brain Res Bull 1995; 38:1-9. [PMID: 7552368 DOI: 10.1016/0361-9230(95)00063-k] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Previous receptor damage studies and artificial rearing (AR) studies in rat have demonstrated that orochemical stimulation between the postnatal ages of P2 and P14 is necessary for development of primary gustatory axons and terminal endings in the rostral nucleus of the solitary tract (NST). Objectives of the present experiment were to evaluate the qualitative nature of orochemical stimulation and amount of orochemical stimulation that is necessary to produce normal axonal and terminal development in gustatory recipient zones of the rostral and intermediate NST. To this end, ultra-pure water, 30, 150, and 500 mM NaCl, 80 and 340 mM lactose, whole rat milk, and rat milk that had been subject to extensive dialysis (12-14 kD MWCO) was delivered to independent groups of rat pups during AR procedures. Unstimulated AR animals and matched mother-reared (MR) animals were used as controls. AR animals received experimental orochemical stimulation between the ages of P4 and P10, and were thereafter returned to lactating dams until the time of weaning; MR animals received experimental orochemical stimulation during the course of normal nursing. Following maturation, anterograde fluorescent dual-labeling experiments were conducted to map the course and distribution of primary gustatory axons within the NST. Results show that experimental stimualtion with water during AR procedures is not sufficient to produce normal development of primary gustatory axons and terminal endings in the gustatory NST. Stimulation with 30, 150, and 500 mM NaCl produced normal axonal development in the NST, as did 80 and 340 mM lactose, whole rat milk, and dialyzed rat milk.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- P S Lasiter
- Department of Psychology, Florida Atlantic University, Boca Raton 33431, USA
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Smotherman WP, Robinson SR. Caveats in the study of perinatal behavioral development: utility of fetal study. Neurosci Biobehav Rev 1994; 18:347-54. [PMID: 7984353 DOI: 10.1016/0149-7634(94)90048-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Study of behavior during development presents psychobiologists and neurobiologists with a unique set of problems that should be addressed in the design and analysis of experiments. Some of these caveats have become apparent only with the recent growth in research with subjects around the time of birth. For example, physiological regulation within the maternal-infant dyad, litter effects, the influence of context at the time of testing on performance, and dissociation of age-related change and experience, all are important experimental considerations in developmental study. Manipulation and measurement of behavioral variables in the fetus in vivo can provide one means for circumventing many of the methodological pitfalls that are associated with behavioral study of newborn subjects.
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Affiliation(s)
- W P Smotherman
- Laboratory of Perinatal Neuroethology, Center for Developmental Psychobiology, Department of Psychology, Binghamton University, SUNY 13902-6000
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Tyrka A, Smith GP. SCH23390, but not raclopride, decreases intake of intraorally infused 10% sucrose in adult rats. Pharmacol Biochem Behav 1993; 45:243-6. [PMID: 8516366 DOI: 10.1016/0091-3057(93)90113-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
When 10% sucrose is infused intraorally on postnatal days (PN) 7, 14, and 21, raclopride, a D2 dopaminergic antagonist, does not affect intake at any age and SCH23390, a D1 antagonist, does not affect intake on PN 7 but a large dose decreases intake on PN 14 and 21. To determine if this differential effect of the antagonists on PN 14 and 21 remains after further postnatal development, we studied adult rats in this intraoral intake test. Female (n = 77) and male (n = 81) adult rats, approximately 43 or 96 days old, were deprived for 4 h before intraoral infusion of 10% sucrose. Each rat was tested once and this was its first experience with sucrose. SCH23390 (133 or 267 micrograms/kg), raclopride (357 or 714 micrograms/kg), or saline vehicle was given IP at -15 min. The larger dose of SCH23390 significantly decreased intake of rats that were approximately 43 and 96 days old, but neither dose of raclopride changed intake at either age. These results suggest that D1, but not D2, receptors are necessary components of the central neural network that processes the unconditioned gustatory stimulus of 10% sucrose into mouthing and swallowing movements that maintain ingestion in late preweanling and adult rats under these conditions.
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Affiliation(s)
- A Tyrka
- Department of Psychiatry, Cornell University Medical College, White Plains, NY
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Robinson SR, Hoeltzel TC, Cooke KM, Umphress SM, Smotherman WP, Murrish DE. Oral capture and grasping of an artificial nipple by rat fetuses. Dev Psychobiol 1992; 25:543-55. [PMID: 1487080 DOI: 10.1002/dev.420250802] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Although born blind and deaf, newborn rats exhibit a remarkable capacity to recognize and gain access to the nipples of the lactating mother. However, it is well-known that full-term rat neonates will not attach to an artificial nipple. In the present study, an artificial nipple fashioned from soft vinyl was presented to rat fetuses from E17-E21 of gestation. Fetuses showed side-to-side head movements that resulted in oral capture of the nipple on E18 and exhibited a direct nipple-grasping response from E19 through term. Frame-by-frame analysis of videotape records of E21 rat fetuses revealed that tactile contact with the artificial nipple elicited mouthing, licking directed at the nipple, forelimb treadling, and grasping of the nipple. Fetuses also exhibited components of aversive behavior, including facial wiping and head turning, that appeared to terminate oral contact with the nipple. Morphine pretreatment reduced the expression of aversive responses and promoted licking and grasping of the artificial nipple. In addition to documenting the prenatal ontogeny of this important neonatal behavior, these findings imply a role for endogenous opioids in the newborn rat's first suckling episode.
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Affiliation(s)
- S R Robinson
- Department of Psychology, Binghamton University, New York 13902-6000
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Robinson SR, Smotherman WP. Fundamental motor patterns of the mammalian fetus. JOURNAL OF NEUROBIOLOGY 1992; 23:1574-600. [PMID: 1487750 DOI: 10.1002/neu.480231013] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Techniques that permit direct observation of fetuses in vivo recently have expanded our understanding of prenatal behavioral development in mammals. Although fetal motor activity seems to lack the dynamic, goal-directed character of postnatal behavior, the dimensions that define behavioral organization after birth are applicable to the movements expressed by fetuses. Fetal activity exhibits temporal, sequential, and spatial organization that emerges between the inception of movement and term. Fetal rodents, for example, exhibit coordinated motor patterns antecedent to postnatal righting, locomotion, suckling, maternal-infant communication and grooming behavior, while other action patterns appear to be functional adaptations to the intrauterine niche. Fetuses also are behaviorally responsive to sensory stimulation and changes in environmental conditions in utero. Expression of these behavioral properties emphasizes continuity between prenatal and postnatal life while implying an adaptive role for behavior before birth.
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Affiliation(s)
- S R Robinson
- Department of Psychology, Binghamton University, New York 13902-6000
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Affiliation(s)
- S R Robinson
- Department of Psychology, State University of New York, Binghamton 13902-6000
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Smotherman WP, Robinson SR. Prenatal experience with milk: fetal behavior and endogenous opioid systems. Neurosci Biobehav Rev 1992; 16:351-64. [PMID: 1528524 DOI: 10.1016/s0149-7634(05)80205-2] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The existence of organized responses to milk in newborn mammals, which lack experience at the nipple, implies the prenatal development of neural and behavioral systems for recognizing, obtaining, and processing milk. Many components of milk-directed behavior have been identified in the fetus. The stretch response expressed by neonatal rats during milk ejection at the nipple can be elicited before birth by infusing milk into the mouth of the fetus. Milk promotes reorganization of fetal motor behavior, facilitates expression of the stretch response, and alters fetal responsiveness to cutaneous stimulation. Pretreatment of fetuses with opioid agonists and antagonists has confirmed involvement of the mu and kappa opioid systems in mediating the effects of milk. Opioids appear to play a dual role in milk-oriented behavior: Initially, opioids suppress behavioral responses of the fetus and neonate to novelty, permitting ingestion of milk, and secondarily, opioid activity can promote learning at the nipple by functioning as a reinforcer. Study of milk-directed behavior in the fetus may promote better understanding of the special needs of preterm human infants.
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Affiliation(s)
- W P Smotherman
- Laboratory of Perinatal Neuroethology, SUNY, Binghamton 13902-6000
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Robinson SR, Smotherman WP. Motor competition in the prenatal ontogeny of species-typical behaviour. Anim Behav 1992. [DOI: 10.1016/s0003-3472(05)80758-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Lasiter PS. Postnatal development of gustatory recipient zones within the nucleus of the solitary tract. Brain Res Bull 1992; 28:667-77. [PMID: 1617454 DOI: 10.1016/0361-9230(92)90245-s] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Previous studies have examined pre- and postsynaptic development of the first-order central gustatory relay, located in the rostral nucleus of the solitary tract (NST). This region of the NST is innervated by primary gustatory axons arising from the facial-intermediate nerve. However, a large portion of the gustatory NST is innervated by axons arising from the glossopharyngeal nerve, and although the time course for development of N.VII recipient zones has been defined development of glossopharyngeal afferent terminal fields has not been examined. Moreover, the time course for development of projection neurons located postsynaptic to gustatory afferent axons has not been examined in any portion of the NST. The objectives of the present study were to 1) define the time course for development of N.VII and N.IX terminal fields and 2) examine temporal relationships between development of afferent terminal fields and development of projection neurons located postsynaptic to gustatory afferent axons. To this end, triple fluorescent labeling procedures were used to simultaneously visualize developing axons and projection neurons. Results show that afferent terminal fields develop along the rostrocaudal axis of the NST. Axons of the N.VII terminal field are present in the rostral NST at P1 and develop to approximately P25. Axons and terminal endings of N.IX do not enter the NST until approximately P9-P10, and these terminal fields develop within the intermediate NST until approximately P45. Many NST neurons destined to project axons to the second-order central gustatory relay, located in the caudal parabrachial nucleus (PBN), do not possess axonal connections with the PBN during the first 2-3 weeks of postnatal life. As afferent terminal fields develop, these neurons establish connections with the PBN between the ages of approximately P7 and P45-P60. The delay between afferent terminal field development and development of PBN projection neurons in the N.VII terminal field is approximately 3 weeks. The delay between pre- and postsynaptic development in the N.IX terminal field is approximately 1 week. Potential relationships between pre- and postsynaptic development are discussed, in addition to relationships between anatomical development in the NST and the emergence of taste-guided behaviors.
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Affiliation(s)
- P S Lasiter
- Department of Psychology, Florida Atlantic University, Boca Raton 33431
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Robinson SR, Smotherman WP. The amniotic sac as scaffolding: prenatal ontogeny of an action pattern. Dev Psychobiol 1991; 24:463-85. [PMID: 1797592 DOI: 10.1002/dev.420240703] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Intraoral lemon infusion elicits facial wiping behavior in fetal rats on Days 20 and 21 of gestation. On Day 19, fetuses tested in a warm saline bath respond to infusion but do not express the wiping response. In contrast, fetuses tested within the amniotic sac exhibit wiping. Fetal movements after infusion were analyzed on Days 19 and 20 in both the bath and amnion environments. Facial wiping is assembled from simpler components in both real time (during the 15 s after infusion) and developmental time (over Days 19-20 of gestation). In real time, the wiping response occurs following a brief period of fetal activity comprising head and forelimb movements. After the wiping bout is initiated, strokes by left and right forelimbs increase in duration and become synchronized. In developmental time, components of the wiping response (forelimb strokes) are consistently expressed on Day 19, but other components (head stabilization) are lacking when fetuses are tested in bath. The amniotic sac appears to provide scaffolding that reduces head movement and promotes paw-face contact, thus facilitating facial wiping.
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Affiliation(s)
- S R Robinson
- Department of Psychology, State University of New York, Binghamton 13902-6000
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Lasiter PS. Effects of early postnatal receptor damage on dendritic development in gustatory recipient zones of the rostral nucleus of the solitary tract. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 1991; 61:197-206. [PMID: 1721561 DOI: 10.1016/0165-3806(91)90132-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The rostral gustatory zone of the nucleus of the solitary tract (NST) exhibits extensive anatomical development during the first 3 weeks of postnatal life, and this development requires the presence of intact gustatory receptors during a critical period. We have previously shown that unilateral damage induced to fungiform papillae of the anterior tongue at postnatal day 2 (P2) alters normal migration and ramification of chorda tympani (CT) axons in the rostral NST. In addition to alterations of axonal development, P2 receptor damage decreases the intraneuronal distance between neurons that project axons to the second-order central gustatory relay, located in the caudal parabrachial nucleus (PBN). This observation suggested that P2 receptor damage may alter both axonal development and dendritic development in the rostral gustatory NST. The present study evaluated potential changes in dendritic development of PBN projection neurons following either P2 or P10 receptor damage. Morphological studies were first conducted to quantitatively define somatic characteristics of neurons that project axons to the PBN. Independent experiments used fluorescent labeling combined with subsequent Golgi-impregnation to study dendritic architecture of identified PBN projection neurons. Results confirmed that P2 receptor damage alters dendritic development of PBN projection neurons located in CT terminal fields. Anterior tongue receptor damage at P2 (1) reduces planar length of first- and second-order dendritic branches, (2) reduces the mean number of second-order branches per neuron, and (3) reduces the density of spine processes on second-order dendritic branches. A critical period exists for these effects, similar to that reported for axonal development, insofar as P2 receptor damage alters dendritic development of PBN projection neurons, whereas P10 receptor damage does not. Dendrites of identified PBN projection neurons located in regions of the NST that receive primary afferent axons from the glossopharyngeal nerve are not affected by anterior tongue damage at P2. These results show that early postnatal receptor damage influences both pre- and postsynaptic development in the rostral gustatory NST. These anatomical changes are undoubtedly related to alterations in taste-guided behaviors that are observed following P2 receptor damage.
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Affiliation(s)
- P S Lasiter
- Department of Psychology, Florida Atlantic University, Boca Raton 33431
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Tyrka A, Smith GP. Potency of SCH 23390 for decreasing sucrose intake in rat pups depends on mode of ingestion. Pharmacol Biochem Behav 1991; 39:955-61. [PMID: 1837153 DOI: 10.1016/0091-3057(91)90059-b] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
To investigate the role of dopaminergic mediation of the positive reinforcing effect of sucrose during development, we tested the effects of the D-1 antagonist, SCH 23390, on the intake of 10% sucrose in 7-, 14-, and 21-day-old rats during independent ingestion (pups lick sucrose from the floor of a beaker) or during continuous intraoral infusion of sucrose. SCH 23390 inhibited intake more in independent ingestion tests than in intraoral catheter tests. At 7 and 14 days this difference was qualitative--SCH 23390 was efficacious in independent ingestion tests, but not in intraoral catheter tests. At 21 days the difference was quantitative--SCH 23390 decreased intake in both tests, but was more potent in independent ingestion tests. SCH 23390 decreased intake during independent ingestion tests without changing latency to eat or time-sampled activity scores at 7 and 14 days, but not at 21 days; thus the inhibition of intake is not accounted for by a generalized motor deficit at 7 and 14 days. Possible explanations for the differential potency include density of reinforcement, pattern of central dopamine metabolism, and interference with the appetitive movements required to maintain contact with the sucrose in the independent ingestion test.
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Affiliation(s)
- A Tyrka
- Department of Psychiatry, Cornell University Medical College, NY
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Hoffmann H, Hunt P, Spear N. Ontogenetic differences in CS palatability following conditioned taste aversion training. LEARNING AND MOTIVATION 1991. [DOI: 10.1016/0023-9690(91)90012-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Smotherman WP, Robinson SR, Ronca AE, Alberts JR, Hepper PG. Heart rate response of the rat fetus and neonate to a chemosensory stimulus. Physiol Behav 1991; 50:47-52. [PMID: 1946730 DOI: 10.1016/0031-9384(91)90496-b] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Resting heart rate (HR) and HR responses of fetal and neonatal rats are described before and after intraoral infusion of isotonic saline or lemon solution. Stable measurements of resting HR were obtained for fetuses over the last three days of gestation (E19, E20, E21) and pups on the day of birth (P0) and four subsequent postnatal ages (P1, P3, P5, P7). Resting HR decreased significantly on P0 relative to the three prenatal ages and exhibited a linear increase thereafter. Variability in resting HR was pronounced on E21, decreased sharply after birth, and gradually increased through P7. Developmental changes in the HR response of fetuses and pups were evident following infusion of lemon. Fetal HR responses to lemon were characterized by bradycardia, which increased in magnitude through P1, diminished after P1, and eventually changed to tachycardia by P7. Both resting HR and HR responses to chemosensory stimulation point to the immediate perinatal period as a time of quantitative and qualitative change during sensory development.
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Abstract
Previous demonstrations of prenatal learning have relied upon experimental protocols involving training at one gestational age and testing at a later age, potentially confounding effects of experience and retention with developmental changes in the fetus's behavioral repertoire. In this study, a single-session paradigm, which involved the pairing of a neutral chemosensory stimulus (sucrose CS) with a second stimulus that activates behavior (lemon US), was used to assess the learning capacity of the rat fetus. Four CS-US pairings were effective in promoting behavioral activity in 20-day-old rat fetuses when they were reexposed to the sucrose CS alone. The functional expression of conditioned behavioral activation on day 20 of gestation occurs at a time when CNS structures, many of which are involved in sensory processing and learning in older animals, are still undergoing rapid differentiation in the rat fetus.
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Affiliation(s)
- W P Smotherman
- Department of Psychology State University of New York, Binghamton 13902-6000
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Smotherman WP, Robinson SR. Olfactory bulb transection alters fetal behavior after chemosensory but not tactile stimulation. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 1990; 57:175-80. [PMID: 2073718 DOI: 10.1016/0165-3806(90)90043-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Rat fetuses respond to an intraoral infusion of lemon extract with an increase in overall activity and facial-wiping behavior. Other studies have suggested a role for olfaction in mediating fetal responses to chemosensory stimuli. In the present study, a micro-knife was used to surgically isolate the main and accessory olfactory bulbs from more caudal structures in the fetal brain. Fetuses that received this transection procedure or a sham treatment showed normal levels of non-evoked motor activity during the period prior to chemosensory infusion. Surgical isolation of the olfactory bulbs had no effect on fetal response to perioral tactile stimulation. Behavioral responses to infusion were diminished but not eliminated in fetuses with olfactory bulb transections. The olfactory bulb, which is functional in spite of its anatomical immaturity, plays a role in the control of fetal behavior.
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Affiliation(s)
- W P Smotherman
- Department of Psychology, State University of New York, Binghamton 13901
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Lasiter PS, Kachele DL. Effects of early postnatal receptor damage on development of gustatory recipient zones within the nucleus of the solitary tract. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 1990; 55:57-71. [PMID: 2208641 DOI: 10.1016/0165-3806(90)90106-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The temporal correspondence between neuroanatomical and neurophysiological development of peripheral and central gustatory neurons has suggested that morphological development of the first-order central gustatory relay, located in the rostral nucleus of the solitary tract (NST), may be dependent on afferent input from peripheral gustatory pathways. The objective of the present study was to determine the effects of perinatal receptor damage on development of gustatory recipient zones within the rostral and intermediate NST. Results show that damage induced to fungiform receptors of the anterior tongue at postnatal day 2 (P2) alters normal development of NST terminal fields associated with the chorda tympani nerve (CT) and greater superficial nerve (GSP), and that alterations in the CT/GSP terminal field persist in adulthood after peripheral gustatory receptors have regenerated. Damage induced to fungiform receptors at P2 does not alter the normal development of glossopharyngeal terminal fields in the intermediate NST. Receptor damage produced at P10 and P20 is without effect on normal development of the CT/GSP terminal field. Thus, fungiform receptor damage at P2 produces specific alterations in the development of NST terminal fields that receive projections from the facial-intermediate nerve, and receptor damage effects are only obtained during a critical period of postnatal development. P2 receptor damage has the overall effect of eliminating caudally directed migration of CT/GSP axons to additional projection neurons that establish connections with the second-order central gustatory relay located in the parabrachial nucleus (PBN). Behavioral studies were conducted to determine the functional consequences of early receptor damage. Results from behavioral studies show that bilateral damage to fungiform papillae at P2 alters normal adult preferences to low and intermediate concentrations of NaCl and sucrose tastes, yet aversions to citric acid and quinine HCl are not obviously affected. Therefore, anatomical alterations in the CT/GSP terminal field produced by P2 receptor damage are accompanied by specific changes in adult taste preference responses.
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Affiliation(s)
- P S Lasiter
- Department of Psychology, Florida Atlantic University, Boca Raton 33431
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Lasiter PS, Kachele DL. Postnatal development of protein P-38 ('synaptophysin') immunoreactivity in pontine and medullary gustatory zones of rat. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 1989; 48:27-33. [PMID: 2502329 DOI: 10.1016/0165-3806(89)90091-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Neurons located in gustatory zones of the nucleus of the solitary tract (NST) and parabrachial nucleus (PBN) exhibit extensive morphological development during the first 5-7 weeks of rat's postnatal life. The present study examined the time course for development of protein P-38 ('synaptophysin'), a specific integral membrane glycoprotien of clear synaptic vesicles, in the rostral NST and PBN. Results show that volumetric fractions of P-38 immunoreactions increase in the NST from P1 to P10, and are adult-like in the NST after approximately P11. In contrast, volumetric fractions of P-38 immunoreactivity increase in the PBN between approximately P11 and P30. Because we have previously demonstrated that dendritic growth in the rostral gustatory NST precedes dendritic growth in the PBN, these results confirm that maturation of both presynaptic and postsynaptic constituents of brainstem gustatory relays develop in a temporally sequential manner. Relationships between neurological development of brainstem gustatory relays and the ontogeny of taste-guided responses are discussed.
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Affiliation(s)
- P S Lasiter
- Department of Psychology, Florida Atlantic University, Boca Raton 33431
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Abstract
Intracerebroventricular injections of renin in suckling rat pups increased intake of NaCl solutions when they were orally infused 5 hr after injection. The appetite for saline solution was evident in pups as young as 3 days, was greater in females, and was specific insofar as intake of milk, either by suckling or by oral infusion, was not affected. Three-day-old pups increased intake only to 12% NaCl, the acceptable concentration of NaCl becoming lower in older pups. These results suggest, first, that, as is true for feeding and drinking, the brain mechanism for salt appetite is competent for expression of the behavior in the very young rat pup, and second, that its angiotensinergic neural substrate is distinct from that which mediates the dipsogenic effect of the hormone.
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Affiliation(s)
- M Leshem
- Biology Department, University of Pennsylvania, Philadelphia
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Lasiter PS, Wong DM, Kachele DL. Postnatal development of the rostral solitary nucleus in rat: dendritic morphology and mitochondrial enzyme activity. Brain Res Bull 1989; 22:313-21. [PMID: 2468401 DOI: 10.1016/0361-9230(89)90059-2] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Morphological and metabolic development of the gustatory zone of the rostral nucleus of the solitary tract (NST) was examined in rat. Transganglionic transport of horseradish peroxidase (HRP) was used to visualize the organization of gustatory projections to the rostral gustatory NST in rats aged postnatal day 1 (P1) to P34. Golgi impregnation studies were performed to analyze morphological development of dendrites in regions of the rostral NST that were identified as anterior tongue terminal fields. Results demonstrate that afferent fibers of the anterior tongue project to the rostral NST in rats as young as P1. The volume of NST terminal fields increased from P1 to approximately P16-P20, and was adult-like after approximately P20. Developmental increases in terminal field volume resulted from a preferential expansion in the rostrocaudal plane. Planar length of first-order dendrites associated with fusiform, multipolar, and ovoid neurons, and second-order dendrites of fusiform and ovoid neurons, increased approximately three-fold between P4 and P16-20. First-order dendritic length for all morphological types was adult-like after approximately 20-25 days of age, whereas second-order dendritic length of multipolar neurons increased significantly between P30 and P60-70. Histochemical studies confirmed that activity of the mitochondrial respiratory enzymes cytochrome c oxidase (EC 1.9.3.1), succinate dehydrogenase (EC 1.3.99.1), and NADH-dehydrogenase (EC 1.6.99.3) increased monotonically during the developmental period in which planar growth of first-order dendrites was observed. The present results, in combination with results from previous studies, indicate that morphological and metabolic development fo the NST occurs concomitantly with morphological development of taste receptors and peripheral gustatory nerves.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- P S Lasiter
- Department of Psychology, Florida Atlantic University, Boca Raton 33431-0991
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Abstract
Rat pups 3 to 15 days of age were infused with sucrose or Polycose solutions (.03 or .3 M) through oral cannulas and their solution intake, mouthing behavior, and general locomotor activity were recorded. Overall, the pups displayed similar ingestive responses to Polycose and sucrose. They discriminated between .3 M sucrose and water as early as 6-days of age, and between .3 M Polycose and water as early as 9-days of age. However, at the .03 M concentration the pups responded to Polycose before they responded to sucrose. The results confirm previous reports that rat pups have an unlearned preference for sucrose and demonstrate that a similar preference exists for starch-derived polysaccharides. The Polycose appetite displayed by the neonatal rats is consistent with results obtained with adult animals which suggest that rats have taste receptors for starch-derived polysaccharides as well as for sugars.
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Affiliation(s)
- M Vigorito
- Department of Psychology, Brooklyn College, NY 11210
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Abstract
Twenty-four-hour deprived infant rats from 1 to 12 days of age were exposed to the odor of milk, either by itself or accompanied by oral infusions of water, sucrose, quinine, or milk (Experiment 1). Pups from 3 to 9 days of age became behaviorally active, and mouthed and probed in response to the odor of milk, even in the absence of oral infusions. Six- and 9-day-old pups also increased their intake of various test solutions in the presence of milk odor. This responsiveness to milk odor was not seen in 1-day-old pups, and waned by 12 days of age. Other stimulus odors that were presented in the same context (Experiment 2) failed to elicit such intense behavioral activation, indicating that there was some degree of specificity in the responsiveness to milk odor. Finally, 2 manipulations that influence pups' ingestion of milk, deprivation and ambient temperature, were found to influence pups' responses to milk odor (Experiment 3).
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