Maternal obesity programs offspring non-alcoholic fatty liver disease through disruption of 24-h rhythms in mice.

BACKGROUND: Maternal obesity increases offspring propensity to metabolic dysfunctions and to non-alcoholic fatty liver disease (NAFLD), which may lead to cirrhosis or liver cancer. The circadian clock is a transcriptional/epigenetic molecular machinery synchronising physiological processes to coordinate energy utilisation within a 24-h light/dark period. Alterations in rhythmicity have profound effects on metabolic pathways, which we sought to investigate in offspring with programmed NAFLD. METHODS: Mice were fed a standard or an obesogenic diet (OD), before and throughout pregnancy, and during lactation. Offspring were weaned onto standard or an OD at 3 weeks postpartum and housed in 12:12 light/dark conditions. Biochemical and histological indicators of NAFLD and fibrosis, analysis of canonical clock genes with methylation status and locomotor activity were investigated at 6 months. RESULTS: We show that maternal obesity interacts with an obesogenic post-weaning diet to promote the development of NAFLD with disruption of canonical metabolic rhythmicity gene expression in the liver. We demonstrate hypermethylation of BMAL-1 (brain and muscle Arnt like-1) and Per2 promoter regions and altered 24-h rhythmicity of hepatic pro-inflammatory and fibrogenic mediators. CONCLUSIONS: These data implicate disordered circadian rhythms in NAFLD and suggest that disruption of this system during critical developmental periods may be responsible for the onset of chronic liver disease in adulthood.

Best practice principles for management of children with developmental coordination disorder (DCD): results of a scoping review.

BACKGROUND: Developmental coordination disorder (DCD) is a prevalent health condition that is frequently unrecognized despite the substantial evidence that has accumulated regarding how it affects children's health, education and skills. Most literature focuses on measurement of impairment and description of intervention approaches for individual children; little is known about the principles that should guide best practice and service delivery for children with DCD as a population. The purpose of this study was to identify these principles. METHODS: A scoping review was used to 'map' the information available to inform intervention and service delivery. Scholarly and grey literature written in English was identified in six databases, using a combination of keywords (e.g. guidelines, management, models and DCD); a 'snow-balling' technique was also used in Canada and the UK to access clinical protocols used in publicly funded health care systems. Over 500 documents were screened: 31 met inclusion criteria as they outlined practice principles for children with DCD as a population. Data regarding best practices were independently extracted by two reviewers and then compared with achieve consistency and consensus. RESULTS: Two over-arching themes emerged, with five principles: (1) Organizing services to efficiently meet the comprehensive needs of children (e.g. Increasing awareness of DCD and coordination; Implementing clearly defined pathways; Using a graduated/staged approach); (2) Working collaboratively to offer evidence-based services (e.g. Integration of child and family views; Evidence-based interventions fostering function, participation and prevention). CONCLUSION: Numerous documents support each of the principles, reflecting agreement across studies about recommended organization of services. While these principles may apply to many populations of children with disabilities, this review highlights how essential these principles are in DCD. Researchers, managers, clinicians, community partners and families are encouraged to work together in designing, implementing and evaluating interventions that reflect these principles.

The extreme yet transient nature of glacial erosion.

Ice can sculpt extraordinary landscapes, yet the efficacy of, and controls governing, glacial erosion on geological timescales remain poorly understood and contended, particularly across Polar continental shields. Here, we assimilate geophysical data with modelling of the Eurasian Ice Sheet - the third largest Quaternary ice mass that spanned 49°N to 82°N - to decipher its erosional footprint during the entire last ~100 ka glacial cycle. Our results demonstrate extreme spatial and temporal heterogeneity in subglacial erosion, with rates ranging from 0 to 5 mm a-1 and a net volume equating to ~130,000 km3 of bedrock excavated to depths of ~190 m. A hierarchy of environmental controls ostensibly underpins this complex signature: lithology, topography and climate, though it is basal thermodynamics that ultimately regulates erosion, which can be variously protective, pervasive, or, highly selective. Our analysis highlights the remarkable yet fickle nature of glacial erosion - critically modulated by transient ice-sheet dynamics - with its capacity to impart a profound but piecemeal geological legacy across mid- and high latitudes.

Induction of HO-1 and redox signaling in endothelial cells by advanced glycation end products: a role for Nrf2 in vascular protection in diabetes.

BACKGROUND AND AIMS: Hyperglycemia and diabetes are associated with increased formation of advanced glycation end products and enhanced oxidative stress, leading to the progression of diabetic vascular disease. We have investigated the mechanisms by which AGE-modified bovine albumin (AGE-BSA) induces reactive oxygen species (ROS) generation, leading to nuclear factor-erythroid 2-related factor (Nrf2) dependent induction of the antioxidant genes heme oxygenase-1 (HO-1) and NADPH:quinone oxidoreductase 1 (NQO1) in bovine aortic endothelial cells. METHODS AND RESULTS: AGE-BSA (100 µg ml⁻¹, 0-24 h), but not native BSA, elicited time-dependent increases in ROS generation, Nrf2 nuclear translocation and enhanced mRNA and protein expression of HO-1 and NQO1, but not glutathione peroxidase-1. Inhibition of ROS production with the superoxide scavenger Tiron or inhibitors of flavoproteins (diphenylene iodonium) and NADPH oxidase (apocynin), but not eNOS (L-NAME) or mitochondria complex I (rotenone) abrogated HO-1 induction by AGE-BSA. Although AGE-BSA induced rapid phosphorylation of JNK and Akt, only inhibition of JNK abrogated HO-1 expression, implicating the involvement of the JNK signaling pathway in AGEs activation of Nrf2/ARE-linked antioxidant gene expression. CONCLUSION: Our findings establish that AGEs activate redox sensitive Nrf2-dependent antioxidant gene expression in bovine aortic endothelial cells, providing an adaptive endogenous defense against oxidative stress in diabetes.

Protein kinase C activation antagonizes melatonin-induced pigment aggregation in Xenopus laevis melanophores.

The pineal hormone, melatonin (5-methoxy N-acetyltryptamine) induces a rapid aggregation of melanin-containing pigment granules in isolated melanophores of Xenopus laevis. Treatment of melanophores with activators of protein kinase C (PKC), including phorbol esters, mezerein and a synthetic diacylglycerol, did not affect pigment granule distribution but did prevent and reverse melatonin-induced pigment aggregation. This effect was blocked by an inhibitor of PKC, Ro 31-8220. The inhibitory effect was not a direct effect on melatonin receptors, per se, as the slow aggregation induced by a high concentration of an inhibitor of cyclic AMP-dependent protein kinase (PKA), adenosine 3',5'-cyclic monophosphothioate, Rp-diastereomer (Rp-cAMPS), was also reversed by PKC activation. Presumably activation of PKC, like PKA activation, stimulates the intracellular machinery involved in the centrifugal translocation of pigment granules along microtubules. alpha-Melanocyte stimulating hormone (alpha-MSH), like PKC activators, overcame melatonin-induced aggregation but this response was not blocked by the PKC inhibitor, Ro 31-8220. This data indicates that centrifugal translocation (dispersion) of pigment granules in Xenopus melanophores can be triggered by activation of either PKA, as occurs after alpha-MSH treatment, or PKC. The very slow aggregation in response to inhibition of PKA with high concentrations of Rp-cAMPS, suggests that the rapid aggregation in response to melatonin may involve multiple intracellular signals in addition to the documented Gi-mediated inhibition of adenylate cyclase.

5-hydroxytryptophan elevates serum melatonin.

Daytime administration of 5-hydroxytryptophan to sheep elevated serum melatonin more than sevenfold within 2 hours. This suggests that administration of 5-hydroxytryptophan could be used as the basis of a clinical test of pineal function and that melatonin might mediate some clinical effects of 5-hydroxytryptophan.

Assistive devices and cerebral palsy: factors influencing the use of assistive devices at home by children with cerebral palsy.

BACKGROUND: There is a growing awareness of the significance of gaining insights into device users' needs in their everyday usage in order to maximize the potential of assistive device intervention. However, current studies in this field are likely to focus more upon adult users' or adult carers' perspectives and, accordingly, the opinions of young users seem to be overlooked. In order to take the gap into consideration, this study aimed to explore the usability of assistive devices at home by children with cerebral palsy and consider the underlying factors related to the device usage in this setting mainly from the children's perspectives. METHODS: Semi-structured interviews were adopted as the main data collection instrument. A total of 30 participants were involved in the study, including 15 Taiwanese children with cerebral palsy and 15 mothers. RESULTS: The results showed a low frequency of device use at home by the participating children. Four factors leading to low device use at home were identified, including children's reluctance, mothers' perspectives, physical environmental barriers and device-related barriers. CONCLUSIONS: The results highlight the need, when considering the usability of assistive devices, to take into account three interactive factors, namely, the personal, device and environmental factors. They also demonstrate the importance of taking children's different developmental stages and unique personal experiences into consideration in understanding the influence of assistive device intervention for children with cerebral palsy.

Assistive devices and cerebral palsy: the use of assistive devices at school by children with cerebral palsy.

BACKGROUND: Although the importance of providing disabled children with assistive devices has always been highlighted, most studies in the field of assistive device research seek the participation of adult users or adult carers. Accordingly, the opinions of young users themselves seem to be overlooked. To start to address the gap, this study aimed to understand the children's perspectives regarding device use in school and to explore the factors related to their device utilization in this setting. METHODS: Semi-structured interviews were adopted as the main data collection instrument. A total of 44 participants were involved, including 15 Taiwanese children with cerebral palsy, aged between 8 and 15 years, 15 mothers and 14 teachers. RESULTS: The interview results show a high frequency of device use in school which can be attributed to children's willingness, teachers' attitudes, mothers' support, physical environmental factors and device-related features. CONCLUSIONS: The findings not only demonstrate the significance of child-environment interaction but also provide evidence that children's views may be different from those of adults because they are at a different developmental stage and act out different roles in their environment.

Enhanced vascular responses to adrenomedullin in mice overexpressing receptor-activity-modifying protein 2.

Adrenomedullin (AM) levels are elevated in cardiovascular disease, but little is known of the role of specific receptor components. AM acts via the calcitonin receptor-like receptor (CLR) interacting with a receptor-activity-modifying protein (RAMP). The AM1 receptor is composed of CLR and RAMP2, and the calcitonin gene-related peptide (CGRP) receptor of CLR and RAMP1, as determined by molecular and cell-based analysis. This study examines the relevance of RAMP2 in vivo. Transgenic (TG) mice that overexpress RAMP2 in smooth muscle were generated. The role of RAMP2 in the regulation of blood pressure and in vascular function was investigated. Basal blood pressure, acute angiotensin II-raised blood pressure, and cardiovascular properties were similar in wild-type (WT) and TG mice. However, the hypotensive effect of IV AM, unlike CGRP, was enhanced in TG mice (P<0.05), whereas a negative inotropic action was excluded by left-ventricular pressure-volume analysis. In aorta relaxation studies, TG vessels responded in a more sensitive manner to AM (EC50, 8.0+/-1.5 nmol/L) than WT (EC50, 17.9+/-3.6 nmol/L). These responses were attenuated by the AM receptor antagonist, AM(22-52), such that residual responses were identical in all mice. Remaining relaxations were further inhibited by CGRP receptor antagonists, although neither affected AM responses when given alone. Mesenteric and cutaneous resistance vessels were also more sensitive to AM in TG than WT mice. Thus RAMP2 plays a key role in the sensitivity and potency of AM-induced hypotensive responses via the AM1 receptor, providing evidence that this receptor is a selective target for novel therapeutic approaches.

Does subtype of developmental coordination disorder count: is there a differential effect on outcome following intervention?

It is well known that developmental coordination disorder (DCD) is a heterogeneous condition in which children frequently present with co-occurring conditions in addition to their motor difficulties. This study considered whether there would be a differential effect of a group treatment program on subtypes of perceptual and movement problems or associated co-occurring conditions. A subset of children (n=43) from a larger clinical sample (n=100) with DCD participated in a 214 year cross-over intervention study which followed the cognitive orientation to daily occupational performance (CO-OP) approach. Original subtypes were determined by contrasting the current sample with previously published subtyping studies in DCD [Hoare, D. (1994). Subtypes of developmental coordination disorder. Adapted Physical Activity Quarterly, 11, 158-169; Macnab, J. J., Miller, L. T., & Polatajko, H. J. (2001). The search for subtypes of DCD: Is cluster analysis the answer? Human Movement Science, 20, 49-72]. No advantage was conferred to any subtype although children with more profound and complex difficulties at initial assessment, despite progress following intervention, were most likely to have continuing difficulties at the end of the project.

Effect of egg turning and incubation time on carbonic anhydrase gene expression in the blastoderm of the Japanese quail (Coturnix c. japonica).

1. The gene expression of carbonic anhydrase, a key enzyme for the production of sub-embryonic fluid (SEF), was assessed in turned and unturned eggs of the Japanese quail. The plasma membrane-associated isoforms CA IV, CA IX, CA XII, CA XIV, and the cytoplasmic isoform CA II, were investigated in the extra-embryonic tissue of the blastoderm and in embryonic blood. 2. Eggs were incubated at 37.6 degrees C, c.60% RH, and turned hourly (90 degrees ) or left unturned. From 48 to 96 h of incubation mRNA was extracted from blastoderm tissue, reverse-transcribed to cDNA and quantified by real-time qPCR using gene-specific primers. Blood collected at 96 h was processed identically. 3. Blastoderm CA IV gene expression increased with the period of incubation only in turned eggs, with maxima at 84 and 96 h of incubation. Only very low levels were found in blood. 4. Blastoderm CA II gene expression was greatest at 48 and 54 h of incubation, subsequently declining to much lower levels and unaffected by turning. Blood CA II gene expression was about 25-fold greater than in the blastoderm. 5. The expression of CA IX in the blastoderm was the highest of all isoforms, yet unaffected by turning. CA XII did not amplify and CA XIV was present at unquantifiable low levels. 6. It is concluded that only gene expression for CA IV is sensitive to egg turning, and that increased CA IV gene expression could account for the additional SEF mass found at 84 to 96 h of incubation in embryos of turned eggs.

Neurotrophin-3 administration alters neurotrophin, neurotrophin receptor and nestin mRNA expression in rat dorsal root ganglia following axotomy.

In the months following transection of adult rat peripheral nerve some sensory neurons undergo apoptosis. Two weeks after sciatic nerve transection some neurons in the L4 and L5 dorsal root ganglia begin to show immunoreactivity for nestin, a filament protein expressed by neuronal precursors and immature neurons, which is stimulated by neurotrophin-3 (NT-3) administration. The aim of this study was to examine whether NT-3 administration could be compensating for decreased production of neurotrophins or their receptors after axotomy, and to determine the effect on nestin synthesis. The levels of mRNA in the ipsilateral and contralateral L4 and L5 dorsal root ganglia were analyzed using real-time polymerase chain reaction, 1 day, 1, 2 and 4 weeks after unilateral sciatic nerve transection and NT-3 or vehicle administration via s.c. micro-osmotic pumps. In situ hybridization was used to identify which cells and neurons expressed mRNAs of interest, and the expression of full-length trkC and p75NTR protein was investigated using immunohistochemistry. Systemic NT-3 treatment increased the expression of brain-derived neurotrophic factor, nestin, trkA, trkB and trkC mRNA in ipsilateral ganglia compared with vehicle-treated animals. Some satellite cells surrounding neurons expressed trkA and trkC mRNA and trkC immunoreactivity. NT-3 administration did not affect neurotrophin mRNA levels in the contralateral ganglia, but decreased the expression of trkA mRNA and increased the expression of trkB mRNA and p75NTR mRNA and protein. These data suggest that systemically administered NT-3 may counteract the decrease, or even increase, neurotrophin responsiveness in both ipsi- and contralateral ganglia after nerve injury.

The influence of perturbing the working surface during reaching and grasping in children with hemiplegic cerebral palsy.

PURPOSE: To examine unimanual and bimanual reaching and grasping in children with hemiplegic cerebral palsy with particular emphasis on the nature and extent of interlimb coupling when the working surface is perturbed. METHOD: Nine children with hemiplegic cerebral palsy and 7 control children with no movement difficulties took part in the study. Children were asked to pick up a cube unimamually and bimanually when the surface it was placed on was either sloping away from the child (Experiment 1) or towards the child (Experiment 2). Both 3D kinematic data and video data were gathered and qualitative descriptions of video data were made. RESULTS: The working surface did indeed influence the nature and extent of interlimb coupling and this varied from participant to participant. Analysis of the displacement data revealed that during the bimanual condition lower trajectories were produced by both the hemiplegic and non hemiplegic sides, especially in Experiment 2. The control group showed little difference between the unimanual and bimanual condition. CONCLUSIONS: Evidence of interlimb coupling is found, these studies support the findings of our previous work that indicates that there are some benefits to performing bimanual movements in children with hemiplegic cerebral palsy.

Design and synthesis of new N-OMe fluoro-indole melatoninergics.

The synthesis of a series of new N-OMe fluoro-indoles with melatoninergic activity in the Xenopus melanophore assay is described. All of the 4-F substituted compounds, 22a-e and 25a,b, were antagonists on the clonal Xenopus melanophore line. Conversely, the 5-F substituted analogs (15a-e) did not share the same pharmacological profile, as two of them, compounds 15d (R=c-C(3)H(5)) and 15e (R=c-C(4)H(7)), exhibited a weak agonistic and partial agonistic activity, respectively, whilst the other three (15a-c) were all agonists. It seems that in this case the nature of the response (agonist or antagonist activity) is solely dependent on the shape of the R group.

Rat pineal alpha 1-adrenoceptors: identification and characterization using [125I]iodo-2-[beta-(4-hydroxyphenyl)-ethylaminomethyl]tetralone.

[125I]Iodo-2-[beta-(4-hydroxyphenyl)-ethylaminomethyl]tetralone ([125I]HEAT), a selective, high affinity, high specific activity alpha 1-adrenoceptor ligand, is used to characterize alpha-adrenoceptors in the rat pineal gland. Binding of [125I]HEAT to membranes is rapid [association rate constant (Kon) = 3.1 nM-1 min-1] and readily reversible either by 100-fold dilution or by addition of excess unlabeled HEAT [apparent dissociation rate constant (Koff) = 0.153 min-1). Saturation experiments indicate a single class of noncooperative binding sites with an equilibrium binding constant (KD) of 41 +/- 9 pM and a Bmax of 399 +/- 63 fmol/mg protein. The relative potency of a number of adrenoceptor agonists and antagonists in competing with [125I] HEAT indicates the receptor is an alpha 1-subtype. In addition, inhibition of binding is stereospecific; (-)epinephrine and norepinephrine are more than 100-fold more potent than their (+)isomers. The identification of alpha 1-adrenoceptors in the pineal gland is consistent with evidence indicating a role for these receptors in the regulation of melatonin synthesis and phosphatidylinositol turnover.

Beta-adrenergic receptor control of rat pineal hydroxyindole-O-methyltransferase.

The nature of the postsynaptic adrenergic receptor on rat pinealocytes which controls hydroxyindole-O-methyltransferase (HIOMT) activity was studied. This enzyme is involved in the synthesis of the pineal hormone melatonin. Adrenergic drugs were administered continuously for a 7-day period to rats in which neural stimulation of the pineal gland was blocked by either superior cervical ganglionectomy or exposure to constant light. l-Isoproterenol, a beta-adrenergic agonist, prevented the fall in enzyme activity that occurs when neural stimulation is interrupted; d-isoproterenol was ineffective. The potency order of different adrenergic agonists was d,l-isoproterenol greater than l-norepinephrine greater than l-epinephrine. Terbutaline, a selective beta 2-adrenergic agonist, was ineffective. The selective alpha 1-adrenergic agonists phenylephrine and methoxamine and the alpha 2-agonist clonidine were also ineffective. High doses of the beta-adrenergic blocker propranolol antagonized the effect of isoproterenol and caused a fall in HIOMT activity in normal rats housed under normal diurnal lighting. This in vivo evidence is consistent with the hypothesis that the neural control of pineal HIOMT is mediated via a beta-adrenergic receptor.

Negative feedback mechanisms: evidence that desensitization of pineal alpha 1-adrenergic responses involves protein kinase-C.

alpha 1-Adrenergic stimulation of the pinealocyte translocates protein kinase-C, which, in turn, has an important positive effect on pineal cell function; translocation amplifies beta-adrenergic stimulation of both cAMP and cGMP. In the present report negative feedback effects of protein kinase-C are described, including inhibition of alpha 1-adrenergically induced increases in cytosolic Ca2+ ([Ca2+]i), phosphatidylinositol hydrolysis, and cGMP in beta-adrenergically stimulated cells. Time-course studies of cGMP and [Ca2+]i responses indicated that the onset of inhibition by the protein kinase-C activator 4 beta-phorbol 12-myristate 13-acetate (PMA) is rapid (less than 5 min). In contrast, PMA has no inhibitory effect on norepinephrine stimulation of cAMP accumulation or the induction of arylalkylamine N-acetyltransferase activity, a cAMP-dependent enzyme. This is consistent with the finding that PMA substitutes for the positive effect of alpha 1-activation and directly potentiates beta-adrenergic stimulation of cAMP production. Although PMA does inhibit alpha 1-adrenergic potentiation of cGMP in beta-adrenergically treated cells, it does not inhibit the potentiation of the cGMP response in beta-adrenergically stimulated cells produced by high K+, A23187, and ouabain, agents that translocate protein kinase-C secondary to elevation of [Ca2+]i. This suggests that translocation of protein kinase-C does not block an effect of Ca2+, but probably blocks an earlier step in adrenergic activation, presumably the alpha 1-adrenergic stimulation of [Ca2+]i. Finally, pretreatment of cells with an alpha 1-agonist markedly reduced cAMP and cGMP responses to subsequent beta-adrenergic stimulation. The data indicate that the following negative feedback mechanism is present in the pinealocyte: alpha 1-adrenoceptor-dependent elevation of [Ca2+]i----protein kinase-C translocation----inhibition of alpha 1-adrenergic dependent elevation of [Ca2+]i. This mechanism appears to function physiologically to provide a negative feedback signal which limits adrenergic responses that are dependent on an increase in [Ca2+]i, including the cAMP and cGMP increases.

Atypical synergistic alpha 1- and beta-adrenergic regulation of adenosine 3',5'-monophosphate and guanosine 3',5'-monophosphate in rat pinealocytes.

The adrenergic control of cAMP and 3',5'-cyclic GMP (cGMP) in dispersed adult rat pinealocytes was investigated. Norepinephrine treatment increased cAMP and cGMP content 60- and 400-fold, respectively; both alpha- and beta-adrenoceptors had to be activated for these responses to occur. Beta-Adrenergic stimulation alone produced only about 6- and 2-fold increase in cAMP and cGMP content, respectively. Alpha-Adrenergic stimulation, which alone had no effect on either cyclic nucleotide concentration, markedly amplified the beta-adrenergic stimulation of both cAMP and cGMP. The relative potency of alpha-adrenergic agonists and antagonists indicates the alpha 1-subclass of adrenoceptors is involved. A role of alpha 1-adrenoceptors in the control of pineal cAMP is consistent with published evidence of the presence of alpha 1-adrenoceptors on pinealocytes and their role in the regulation of N-acetyltransferase activity and melatonin production.

Ovine pineal alpha 1-adrenoceptors: characterization and evidence for a functional role in the regulation of serum melatonin.

Plasma melatonin in sheep increases to nocturnal levels rapidly (10-20 min) after dark onset. This increase is blocked by iv prazosin (1 mg), but not propranolol (6 mg). Prazosin also blocks the elevation in pineal melatonin content after dark onset, but does not significantly alter the rise in N-acetyltransferase activity or the elevation in pineal N-acetylserotonin content. Since the nocturnal elevation in N-acetyltransferase, a neurally regulated event, was unaltered, this suggests that prazosin does not significantly impair the transmission of neural signals from the eye to the gland, but does act on pineal alpha 1-adrenoceptors to block melatonin production. This is supported by binding studies in ovine pineal membranes using [125I] iodo-2-[beta-(4-hydroxyphenyl)ethylaminomethyl]tetralone, which revealed that binding is rapid, reversible, saturable, and stereo-specific. Saturation studies indicated the presence of a single class of binding sites, with an equilibrium binding constant (Kd) of 32 +/- 6 pM and a maximum binding of 139 +/- 19 fmol/mg protein. The relative potencies of several adrenergic agonists and antagonists in competition studies indicated that the receptor belongs to the alpha 1-subclass of adrenoceptors. Together, these data suggest that melatonin synthesis in the sheep pineal gland is controlled in part by an alpha 1-adrenoceptor mechanism at a step beyond N-acetylation.

Reciprocal day/night relationship between serotonin oxidation and N-acetylation products in the rat pineal gland.

Pineal tryptophan, serotonin [5-hydroxytryptamine (5-HT)], N-acetylserotonin, melatonin, 5-hydroxyindoleacetic acid, 5-hydroxytryptophol, 5-methoxytryptophol, and 5-methoxyindoleacetic acid were measured by high pressure liquid chromatography with electrochemical detection. A complete analysis required less than the equivalent of two rat pineal glands. Samples were obtained at eight time points. A reciprocal physiological relationship was found between oxidation and N-acetylation products of 5-HT. 5-HT and the oxidation products 5-hydroxyindoleacetic acid, 5-hydroxytryptophol, 5-methoxytryptophol, and 5-methoxyindoleacetic acid decreased at night, when the N-acetylation products N-acetylserotonin and melatonin increased. These observations are consistent with the hypothesis that circadian changes in the N-acetylation of 5-HT by indoleamine N-acetyltransferase is the major factor controlling circadian changes in the amounts of 5-HT, and 5-HT oxidation and N-acetylation products in the rat pineal gland.